Java Resume Repaso

CHAPTER 0 An Overview of Computers and Programming Languages

public class MyFirstJavaProgram
{
    public static main(String[] args)
    {
        System.out.println("My first java program.");
    }
}

MyFirstJavaProgram.java  --> MyFirstJavaProgram.class

CHAPTER 1 Basic Elements of JAVA

public class SimpleJavaProgram
{
    public static main(String[] args)
    {
        System.out.println("My first java program");
        System.out.println("La suma de 5 + 8 = " + 13 );
        System.out.println("7 + 8 = " + (7 + 8));
    }
}

Primitive Data types
Boolean
Floating-point
      float    -3.4E+38 @ 3.4E+38
            double   -1.7E+308 @ 1.7E+308
Integral
        Integral Data types
            char        2 bytes (16bits)    0 a 65536 ( 2^16 - 1)
            byte        1 byte    (8 bits)    -128 a 127 ( -2^7 @ 2^7 -1 )
            short        2 bytes (16 bits) -32768 a 32767 ( -2^15 @ 2^15 - 1)
            int            4 bytes (32 bits) -2147483648 a 2147483647 (-2^31 @ 2^31 - 1)
            long        8 bytes (64 bits)
           
casting
(int)(7.9)                7.9
(int)(3.3)                3.3
(double)(25)            25.0
(double)(5 + 3)        8.0
(double)(15) / 2  15.0 / 2
                                    15.0 / 2.0 = 7.5
(double)(15 / 2)  (double) (7) because 15/2 = 7
                                    7.0
                                   
CLASS String
"The sum = "  + 12 + 24

Named Constants, Variables, and Assigment Statements

Named Constants
  [static] final datatype IDENTIFIER = value;
   
    final specifies that the value stored in the identifier is fixed and cannot be changed
   
final double CENTIMETERS_PER_INCH = 2.54;
final int NO_OF_STUDENTS = 20;
final char BLANK = ' ';

int first = 13;
char ch = ' ';
double x = 12.23;

count++;   ++count;
count--;     --count;

Creating a Java Program

public class ClassName
{
    classMembers;
}

public static void main(String[] args)
{
    statment1
    ..
    statemenn
}
                   
public class MyProgram
{
   static final int NUM_CONST = 12;
   
     public static void main(String[] args)
     {
             int firstNum;
            int secNum;
           
            firstNum = 12;
            thirtNum = firstNum + NUM_CONST;
           
CHAPTER 2 INPUT/OUTPUT   

Input Read Statement

class Scanner

[static] Scanner console = new Scanner(System.in);

console.nextInt();          as integer
console.nextDouble();                as floating-point
console.next();                            as string
console.nextLine();                    as string, until EOL also reads /n, but not                                                                     retained

//This programilustrates how to read strings and numeric data

import java.util.*;

public class Example2_3
{
  static Scanner console = new Scanner(System.in);
   
    public static void main(String[] args)
    {
        String firstName;
        String SecondName;
       
        int age;
        double weight;
       
        System.out.println("Enter first name, last"
                                            +"name, age, and weight, "
                                            +"separated by spaces.");
        firstName = console.next();
        LastName = console.next();
       
        age = console.nextInt();
        weight = console.nextDouble();
       
        System.out.println("NAme: " + firstName + " " + last Name);
        System.out.println("age: " +  age);
        System.out.println("weight:" + weight);
    }
}

reading a Single Character

ch = console.next().charAt(0);
    }
}

     }
}

\n newline  \t   tab   \b Backspace  \r  return  \\ Backslash \' single quotation  \" double quotation

formating Output with printf

System.out.printf( formatString);
System.out.printf( formatString, argumentList);

System.out.printf("There are %.2f inches in %d centimeters.%n",centimeters / 2.54, centimeters);

%[argument_index$][flags][width][.precision]conversion

    argument_index - is a (decimal) integer indicating the position of the                                                 argument in the argument list, fisrt is referenced as "1$",                                     second "2$" etc...

    flags - is a set of characters that modifies the output format, depends on                     conversion.
   
    width - (decimal) integer indicating the minimum number of characters to be
                    written to the output device.
                   
    precision - (decimal) integer used to restrict the number of characters.
   
    conversion - character indicating the format.
   
        's'    - general     the result as string
        'c' - character the result in a Unicode Character
        'd' - integral    "        "  formatted as a (decimal) integer.
        'e' - floating point  the result formatted as a decimal number in
                    computerized scientific notation
        'f' - floating poing  the result is formatted as a decimal number
        '%' - percent   the result in '%'
        'n' - line separator  platfrom-specific line separator
       
import java.util.*;
public class LabJava
{
    static final int NUMBER = 12;
    static Scanner console = new Scanner(System.in);
   
    public static void main(String[] args){
      int firstnum;
        int secNum;
       
        ...
    }
}
       
File Input/Output

Scanner console = new Scanner(System.in);

class FileReader  in package java.io     //to read a file
class PrintWriter in package java.io     //to write to a file

Scanner inFile = new Scanner(new FileReader("texto.dat"));

file employeeData.txt with: Beto Martinez 45 120.43

import java.util.*;
import java.io.*;

Scanner inFile = new Scanner(new FileReader("employeeData.txt"));

String firstName;
String lastName;

double hoursWorked;
double payRate;
double wages;

firstName = inFile.next();
lastName = inFile.next();

hoursWorked = inFile.nextDouble();
payRate = inFile.nextDouble();

wages = hoursWorked * payRate;

inFile.close();

Storing (Writing) Output to a File

PrintWriter outFile = new PrintWriter("prog.out");

Parsing Numeric Strings

Integer.parseInt(strExpression);
Float.parseFloat(strExpression);
Double.parseDouble(strExpression);

Integer.parseInt("2343");
Integer.parseInt("-832");
Float.parseFloat("34.34");
Float.parseFloat("-532.34");
Double.parseDouble("34.3434342");
Double.parseDouble("-743.323443");

Using Dialog Boxes for Input/Output

package javax.swing;
class JOptionPane;

str = JOptionPane.showInputDialog("Dame tu nombre y presion OK");

JOptionPane.showMessageDialog(parentComponent,
                                                          messageStringExpression,
                                                            boxTitleString, messageType);
           
            messageType:  JOptionPane.ERROR_MESSAGE,
                                        JOptionPane.INFORMATION_MESSAGE,
                                        JOptionPane.PLAIN_MESSAGE,
                                        JOptionPane.QUESTION_MESSAGE,
                                        JOptionPane.WARNING_MESSAGE
                                       
JOptionPane.showMessageDialog( null, "Hola Cabezones!", "Aqui el Titulo",
                                        JOptionPane.INFORMATION_MESSAGE);
                                       
JOptionPane.showMessageDialog( null, "Cantidad = $" + 500.43, "A Cobrar",
                                        JOptionPane.PLAIN_MESSAGE);
                                       
import javax.swing.JOptionPane;
o
import javax.swing.*;

System.exit(0);

String Format Method

String.format(formatString, argumentList)

double x = 15.674;
double y = 235.73;
double z = 9525.9864;

int num = 83;

String str;

String.format("%.2f", x)                                            "15.67"
String.format("%.3f", y)                                            "235.730"
String.format("%.2f", z)                                            "9525.99"
String.format("%7s", "Hello")                                    "   Hello"
String.format("%5d%7.2f", num, x)                            "   83  15.67"
String.format("The value of num = %5d", num)  "The value of num =   83"
str = String.format("%.2f", z)                                "9525.99"

String.format("%.2f", x)
                                       


CHAPTER 3 Introduction to Objects and Classes

int x;
String str;
x = 45;
str = "Java Programming";
str = new String("Java Programmin");

system.gc();  //garbage collector

Modificadores de metodos
public, private, protected, static, abstract

import java.lang.Math.*
Math.pow(2,3)
import static java.lang.Math.*
pow(2,3)

import static java.lang.Math.*;
public class PredefinedMathMethods
{
    public static void main(String[] args)
    {
        System.out.println("2 al cubo" + pow(2,3));
        System.out.println("el mayor de 12.35 y 54.23 = " + max(12.35,54.23) );
        System.out.println("el absouluto de -67 =" + abs(-67));
        System.out.println("floor(43.23) = " + Math.floor(43.32));
        System.out.println("floor(43.23) = " + floor(43.32));
        System.out.println("sin(PI/2) = %2.f %n", sin(PI/2) );
    }
}

Primitive Data Types and Wrapper Classes

class String

StringVarible.StringMethodName(parameters);

name.length();

String sentence;
sentence = "Programming with Java";
                                                                                                    returns
charAt(index)                        sentence.charAt(3)        'g'
indexOf(ch)                            sentence.indexOf('J')         17
                                                sentence.indexOf('a')            5
                                                sentence.indexOf('x')            -1
indexOf(ch, pos)                sentence.indexOf('a', 10)    18
indexOf(str)                        sentence.indexOf("with")    12
                                                sentence.indexOf("ing")        8
indexOf(str, pos)                sentence.indexOf("a", 10)    18
                                                sentence.indexOf("Pr",10) -1
concat(str)                            sentence.concat(" is fun.")
length()                                sentence.lenght()                    21
replace(
charToBeReplaced,
charReplacedWith)                sentence.replace('a','*') "Progr*aming with J*v*"
substring(beginIndex)        sentence.substring(12)        "with Java"
substring(
beginIndex,
endIndex)                                sentence.substring(0,11)    "Programming"
toLowerCase()
toUpperCase()

class Integer

Integer intObj = new Integer(32);
Integer intObj = new Integer("32");

compareTo(anotherInteger)            Integer num1 = new Integer(32);
                                                            Integer num2 = new Integer(12);
                                                            num1.compareTo(num2)
intValue()                                        num1.intValue()                    32                                            doubleValue()                                    num1.doubleValue()            32.0
equals(obj)                                        num1.equals(num2)      value false
parseInt(str)
toString()

class Character            java.lang;
isDigit()
isLetter()
isLowerCase()
isUpperCase()
isSpaceChar()
isWhiteSpace(ch)
toLowerCase(ch)
toUpperCase(ch)

Methods

method modifiers public, private, protected, static, abstract, final

static methods cannot call another nonstatic methods of the class.

Classes
  modifier(s) class ClassIdentifier modifier(s)
    {
      classMembers
    }

Variable Declaration and Object Instantiation

myTemp and yourTemp as reference variables of type Thermometer

Thermometer myTemp;
Thermometer yourTemp;

These statements do not allocate memory spaces to store data.

new className();
or
new className( arg1, arg2, arg3, ..., argN);

myTemp = new Thermometer();
yourTemp = new Thermometer(35);

GUI JFrame, JLabel, Colors, Fonts, JButton, and Handling an Event(Optional)

JFrame
...
JLabel
...
class Color
...
class Font
...
JButton
public JButton(Icon c)
public JButton(String Str)
public JButton(String str, Icon c)
public void setText(String str)
public String getText()
public void addActionListener(ActionListener obj)
        method to register a listener object to the button object
       
private JButton colorB, fontB;

colorB = new JButton("Color");
fontB = new JButton("Font");

pane.add(colorB);
pane.add(fontB);
       
...
Handlig an Event

Clicking a JButton generates an event, known as action event, which sends messages to another object, known as an action listener

public interface ActionListener
{
    public void actionPerformed( ActionEvent e);
}

private class ColorButtonHandler implements ActionListener
{
    public void actionPerformed(ActionEvent e){
       //code to be performed ...
    }
}

  To Create a listener object of type ColorButtonHandler
   
    ColorButtonHandler cHandler;
   
    cHandler = new ColorButtonHandler; //instatiate the object
    colorB.addActionListener(cHandler);
   
Now For JButton fontB   
   
private class FontButtonHandler implements ActionListener
{
  public void actionPerformed(ActionEvent e)
    {
      javaL.setFont(new Font("Arial", Font.BOLD, 24));
        programmingL.setFont(new Font("Arial", Font.BOLD, 24));
    }
}

FontButtonHandler fHandler;
fHandler = new FontButtonHander();
fontB.addActionListener(fHandler);

Listener Class
private class ColorButtonHandler implements ActionListener
{
    public void actionPreforment(ActionEvent e)
    {
      ...
    }
}

Component Object
colorB = new JButton("Color");                                                                                               
cHandler = new ColorButtonHandler();
colorB.addActionListener(cHandler);


CHAPTER 4 Control Structures I: Selection

a.Sequence     b.Selection       c.Repetition

String str1 = "Hello";
String str2 = "Hi";

str1.compareTo(str2)

if (logical expression)
    statement
   
if (logical expression)
  statement1
else
  statement2

Conditional Operator (? : )
testExpression ? expresionIfTrue : expressionIfFalse

System.out.println("Se compraron " + (numero == 1) ? "Articulo" : "Articulos");

switch Structures

switch (expression)
{
    case value1:
        statement1
        break;
    case value2:
        statement2
        break;
    case value3:
        statement
        break;
       
    default:
        statements
}

GUI JTextFields and JPanel
JTextFields
...
    handling the events
...
JPanel
...
    handling the events
...


CHAPTER 5 Control Structures II: Repetition

while (logical expression)
    statement
   
for (initial exp; logical exp; update expression)
  statement
   
do
  statement
while (logical exp);

break statement;

GUI Graphics ans JTextAreas
class Graphics
...

}


class StringBuffer can append() or delete(), use it class instead of String
                                        if you need to change the value of a passed as parameter
                                       
Method Overloading

public void methodXYZ()
public void methodXYZ( int x, double y)
public void methodXYZ( double one, int y)
public void methodXYZ( int x, double y, char ch)

CHAPTER 6 User-Defined Methods and Classes

        Clock
-hr: int
-min: int
-sec: int
+Clock()
+Clock(int, int, int)
+setTime(int, int ,int): void
+setHours(int): void
+setMinutes(int): void
+setSeconds(int): void
+getHours(): int
+getMinutes(): int
+getSeconds(): int
+printTime(): void
+incrementSeconds(): int
+incrementMinutes(): int
+incrementHours(): int
+equals(Clock): boolean
+makeCopy(Clock): void
+getCopy(): Clock


copy constructor

public ClassName(ClassName otherObject)

public Clock(Clock otherClock)
{
  hr = otherClock.hr;
    min = otherClock.min;
    sec = otherClock.sec;
}

static Variables (data members) of a Class

 When you instantiate the object of type MyClass, only the non static data members of the class MyClass become the data members of each object, What about the memory for the static data members of MyClass? For each static data member of the class java allocate memory space only once. All MyClass reference variables refer to the same memory space. In fact, static data members of a class exist before any object of the class type is instantiated, even when no object of the class tyoe is instantiated. Also , static variables are initialized to their default value.

 Accessor and Mutator Methods

 Reference this (optional) used implicit

 Inner Classes - classes defined within other classes are called inner classes

 CHAPTER 7 ARRAYS

 dataType[] arrayName;

 arrayName = new dataType[intExp];

 dataType[] arrayName = new dataType[intExp];

 int[] num = new int[5];

     num[0]   0
         num[1]        0
         num[2]        0
         num[3]        0
         num[4]        0

int[] list = new int[10]
       
         list[0]    0
         list[1]    0
         list[2]    0
         ...
         list[10]    0
       
final int ARRAY_SIZE = 10;
int[] list = new int[ARRAY_SIZE];

Specifying Array Size During Program Execution
int arraysize;
System.out.println("Enter the size of the array");
arraySize = console.nextInt();
System.out.println();

int[] list = new int[arraysize];

double[] sales = {12.35, 32.50, 16.90, 23, 45.68};

int[] list = {10, 20, 30, 40, 50, 60};

 int   alpha[], beta;   //only alpha is array reference variable, beta is int
 int[] gamma, delta;    //array reference variables, both.

 list.length;
sales.length;

for ( int i = 0, i < list.length; i++){
    list[i] = 0;
}

Array Index Out of Bounds Exception
ArrayIndexOutOfBoundException

public static void ArrayAsFormalParameter(int[] listA,
                                                                                    double[] listB,
                                                                                   int num)
{
  //..
}

int[] listA = {5, 10, 15, 20, 25, 30, 35};
int[] listB = new int[listA.length];

listA --> {5, 10, 15, 20, 25, 30, 35}
listB --> {0,  0,  0,  0,  0,  0,  0}

listB = listA;     listB point to listA data

boolean areEqualArrays(int[] firstArray, int[] secondArray)
{
  //..
}

Arrays and Variable Length Parameter List  (dataType ... identifier)

public static double largest(double x, double y)
public static double largest(double x, double y, double z)
public static double largest(double x, double y, double z, double u)
public static double largest(double x, double y ......)

public static double largest(double ... list)
{
  double max = 0.0;
    if (list.length != 0){
      max = list[0];
        for(int i = 1; i < list.lenght; i++){
        if (max < list[i])
            max = list[i];
        }
    }
    return max;
}

Two-Dimensional Arrays

  dataType[][] arrayName;
   
    arrayName = new dataType[intExp1][intExp2];
   
    dataType[][] arrayName = new dataType[intExp1][intExp2];
   
Instance Varialbe length

int[][] matrix = new int[20][15];

matrix.length    is  20

matrix[0].length  is 15

board = new int[5][];
board[0] = new int[6];
board[1] = new int[2];
board[2] = new int[5];
board[3] = new int[7];
board[4] = new int[2];

Initialization During Declaration

int[][] board = { {2,3,1},
                                  {15,25,13},
                                    {20,4,7},
                                    {11,18,14} };
int[][] board = { {2,3,1,5},
                                  {15,25},
                                    {11,18,14} };

public static void printMatrix( int[][] matrix)
{
 ...
}

dataType[][]..[] arrayName = new dataType[intExp1][intExp2] ... [intExpn];

GUI JCheckBoxes, JRadioButtons, JComboBoxes, and JList

JCheckBox
...
JRadioButton
...
JComboBox
...
JList
...

CHAPTER 8 Applications of Arrays

...

class Vector

 Vector can grow and shrink during program execution.

public Vector();
public Vector(int size);
public void addElement(Object insertObj)
     //add element at end
public void insertElementAt(Object insertObj, int index)
  // insert the object at index
    //ArrayIndexOutOfBoundsException
public boolean contains(Object obj)
  //returns true if the Vector object contains the element specified
public Object elementAt(int index)
public Object lastElement()
  //if empty, throws NoSuchElementException
public int indexOf(Object obj)
  // return index of first occurrence
    //if not return -1
public int indexOf(Object obj, int index)
public boolean isEmpty()
  //return true or false
public int lastIndexOf(Object obj)
  //starting at the last element, using backeard search
public int lastIndexOf(Object obj, int index)
public void removeAllElements()
public boolean removeElement(Object obj)
public void removeElementAt(int index)
public void setElementAt(Object obj, int index)
public void setElementAt(Object obj, int index)
public int size()
public String toString()

Vector<String> stringList = new Vector<String>();

stringList.addElement("spring");
stringList.addElement("Summer");
stringList.addElement("Fall");
stringList.addElement("winter");

System.out.println(stringList);

[spring, Summer, Fall, winter]

stringList.addElement("cool", 1);

[spring, cool ,Summer, Fall, winter]

Primitive Data Types and the class Vector

Vector<Integer> list = new Vector<Integer>();

list.addElement(13);
list.addElement(25);
   is similar to
list.addElement(new Integer(13));
list.addElement(new Integer(25));

Vector Objects and the foreach loop

for (type identifier : vectorObject)
  statements
   
Vector<String> stringList = new Vector<String>();

stringList.addElement("one");
stringList.addElement("two");
stringList.addElement("three");
stringList.addElement("four");
stringList.addElement("five");
stringList.addElement("six");

System.out.println( stringList);

for (String str : stringList)
{
    System.out.println(str.toUpperCase());
}

GUI Layout Managers, Menus, and Applets

layout Managers
FlowLayout

Container pane = getContentpane();

pane.setLayout(new FlowLayout());
or
FlowLayout flowLayoutMgr = new FlowLayout();
pane.setLayout( flowLayoutMgr);

flowLayoutMgr.setAlignment(FlowLayout.RIGHT);

BorderLayout
...
Menus
...

Applets   class JApplet  (package javax.swing)

   refers to little aplication
   
public void init()
  //called by the browser of applet viewer to inform this applet that is has
    // been loaded into the systme

public void start()
  //.......that it should start its execution
   
public void stop()
  // .......that it should stop its execution
   
public void destroy()
  //..... that it is being reclaimed and that it should destroy any resources
   
public void showStatus( String msg)
  // display the String msg in the status bar
   
public Container getContentPane()
  // returns the ContentPane object for this applet

public void update(Graphics g)
  // Call the paint() method
   
protected String paramString()
  // Return a string representation of this JApplet; used mainly for debugging
   
import java.awt.Graphics;
import javax.swing.JApplet;

public class WelcomeApplet extends JApplet
{
  public void paint( Grapics g)
    {
        super.paint(g);
        g.drawString("Welcome to Java Programming", 30, 30);
    }
}

<html>
<head>
    <title>Welvome Applet</title>
</head>
<body>
    <object code = "WelcomeApplet.class" width = "250" height = "60">
    </object>
</body>
</html>

appletviewer WelcomeApplet.html

CHAPTER 9  Inheritance and PolyMorphism

Inheritance

modifier(s) class className extends ExistingClassName modifier(s)
{
    memberList
}

public class circle externds shape
{
 ...
}

Using methods of the SuperClass in a Subclass (super)

public void setDimension(double l, double w, double h)
{
  super.setDimension( l, w);
   
    if( h >= 0)
        height = h;
    else
        height = 0;
}

Contructor of the Superclass and Subclass

public Box()
{
    super();
    height = 0;
}

if super is not included in subclass, by default the dafault constructor of the superclass (if any) will be called

Protected Members of a Class -
members of a class that can be accessed by subclass members

class Object

 include method toString() returns the class name followed by the hash code of the Object

public class Clock extends Object
{
  ...
}

Some methods of Object
public Object()   //Constructor
public String toString()
public boolean equals(Object obj)
  // if same memory space
protected Object clone()
  // reference to a copy of the object
protected void finalize()
  // is invoked when the object goes out of scope
   
Java Stream Classes

  Object
            Scanner
            Reader
                    InputStreamReader   FileReader
            Writer
                    PrintWriter
                   
Polymorphism via Inheritance

Java allow us to treat an object of a subclass as an object of its superclass. In Other words, a reference variable of a superclass type can point to an object of its subclass. In some situations, this feature of java can be used to develop generic code for a variety of applictions.

Person name, nameRef;
PartTimeEmployee employee, employeeRef;

name = new Person( "John", "Blair");
employee = new PartTimeEmployee("Susan", "Johnson", 12.50, 45);

nameRef = employee;
System.out.prinrln("nameRef: " + nameRef);

nameRef: Susan Johnson's wages are: $562.5

IF a method of a class is declared final, it cannot be overriden with a new definition in a derived class.

  public final void doSomeThing()
    {
      // this method can not be overriden
    }

Operator instanceOf

p instanceOf BoxShape     returns true if p points to an object of the class                                                         BoxShape

Abstract Methods and Clases

  An Abstract method is a method that has only a heading but no body. The heading of an abstract method contains the reserved word abstract and ends with a semicolon
   
    public void abstract print();
    public abstract object larger(object, object);
    void abstract insert(int insertItem);
   
  An Abstract Class is a class that id declared with the reserved word abstract in its heading.
     - An abstract class can contain instance variables, constructors, and non         abstract methods
     - An abstract class can contain one or more abstract methods.
     - If a class contains an abstract method, the class must be declared                 abstract.
     - You cannot instantiate an object  of an abstract class; you can only
             declare a reference variable of an abstract class type.
     - You can instantiate an object of a subclass of an abstract class, but only
             if the subclass gives the definitions of all the abstract methods of the
            superclass.
           
public abstract class AbstractClassExample
{
  protected int x;
    public abstract void print();
    public void setX(int a)
    {
        x = a;
    }
    public AbstractClassExample()
    {
        x = 0;
    }
}

Interfaces

Java does not support multiple inheritance; a class can extend the definition of only one class. The events are handled by implementing separete interfaces.

An Interface is a type of class that contains only abstract methods and/or named constants. Interfaces are defined using the reserved word interface in place of the reserved word class.

public interface WindowListener
{
    public void windowOpened(WindowEvent e);
    public void windowClosing(WindowEvent e);
    public void windowClosed(WindowEvent e);
    public void windowIconified(WindowEvent e);
    public void windowDeiconified(WindowEvent e);
    public void windowActivated(WindowEvent e);
    public void windowDeactivated(WindowEvent e);
}

public interface ActionListener
{
    public void actionPerformed(ActionEvent e);
}

public class ExampleInterfaceImp implements ActionListener,
                                                                                        WindowListener
{
        // Definitions of each method requierd by interfaces ActionListener
        // and WindowListener
}

Polymorphism via Interfaces

  public interface Employyee
  {
      public double wage();
        public String department();
    }

  Employee newEmployee;
   
    newEmployee = new Employee();  //ilegal
   
    class FullTimeEmployee that implements the interface Employee.
  you can use the reference variable newEmployee to create an object of the class FullTimeEmployee.
   
    newEmployee = new FullTimeEmployee();
   
    double salary = newEmploye.wages();
   
    newEmployee = new PartTimeEmployee();
   
    class FullTimeEmployee contains the method
     public void upDatePayRate(double increment)
     {
       ...
     }
   
    newEmployee.upDatePayRate(23);  //causes compiler error

  ((FullTimeEmployee)newEmployee).upDatePayRate(25);


Composition (Aggregation)
  One or more members of a class are objects of one or more other classes.
    "has-a" relation;for example, "every person has a date of birth"
   
CHAPTER 10 EXception Handling and Events

try/catch/finally block

try
{
  //statements
}
catch (ExceptionClassName objRef1)
{
  // exception handler code
}
catch (ExceptionClassName objRef1)
{
  // exception handler code
}
...
catch (ExceptionClassName objRef1)
{
  // exception handler code
}
finally
{
    // statemets
}

Java Exception Hierarchy

Object - Throwable - Exception

public static void exceptionMethod()
                        throws InputMismatchException, FileNotFoundException
{
 //statements
}

Rethrowing and Throwing an Exception

throw exceptionReference;

throw new ExceptionClassName(MessageString);

import java.util.*;

public class RethrowExceptionExample
{
    static Scanner console = new Scanner(System.in);
   
    public static void main(String[] args)
    {
      int number;
       
        try{
            number = getNumber();
            System.out.println("Line11: number = " + number);
        }
        catch (InputMistmatchException imeRef)
        {
            System.out.println("Line15: Exception " + imeRef);
        }
    }
   
    public static int getNumber()
                            throws InputMismatchException
    {
      int num;
        try
        {
           System.out.println("Line 23: enter an " + "integer:");
             num = console.nextInt();
             return num;
        }
        catch (InputMismatchException imeRef)
        {
           throw imeRef;
             or
             throw new InputMismatchException("getNumber");
        }
    }
}

CHAPTER 12 Generics, Dynamic Representations and Collections


public static void print(int ... list)
{
  for (int elem : list)
        System.out.print(elem + " ");
    System.out.println();
}

public static void print(double ... list)
{
  for (double elem : list)
        System.out.print(elem + " ");
    System.out.println();
}

public static void print(String ... list)
{
  for (String elem : list)
        System.out.print(elem + " ");
    System.out.println();
}

modifier(s) <T> returnType methodName(formal parameter list)
{
  ...
}

T ref;  //ok
ref = new T();  //illegal

public static void print( T ... list)
{
    for ( T elem : list)
        System.out.print(elem + " ");
    System.out.println();
}

Generic Classes

 modifier(s) className<T> modifier(s)
 {
   //class members
 }

 The interface Comparable

 public class Clock implements Comparable


    public int compareTo(Object otherClock)
        {
           Clock temp = (Clock) otherClock;
           
             int hrDiff = hr - temp.hr;
           
             if (hrDiff != 0)
                     return hrDiff;
                   
             int minDiff = min - temp.min;
           
             if ( minDiff != 0)
                     return minDiff;
                   
             return sec - temp.sec;
        }

Generic Methods and Bounded Type Parameters

public static <T> void print(T ... list)
{
   for ( T elem : list)
     {
             System.out.print(elem + " ");
     }
}

 public static <T extends Comparable<T> > T larger(T x, T y)
 {
   if (x.compareTo(y) >= 0)
       return x;
    else
       return y;
 }

 Collections

 class LinkedList

 public class LinkedList<E> extends AbstractSequentialList<E>
 constructors
 public LinkedList();
 public LinkedList(Collection<? extends E> coll)
 methods
 public add(E obj)
 public void add(int index, E elem)
 public void addFirst(E obj)
 public void addLast(E obj)
 public void clear()
 public Object clone()
 public boolean contains(Object obj)
 public E get(int index)
 public E getFisrt()
 public E getLast()
 public int indexOf(Object obj)
 public int lastIndexOf(Objedt obj)
 public ListIterator<E> listIterator(int index)
 public E peek()
 public E poll()
 public E remove(int index)
 public E remove()
 public boolean remove(Object obj)
 public E removeFirst()
 public E removeLast()
 public int size()




 Iterators

 public ListIterator<E> listIterator(int index)
   //return a list of iterator of the elemnts in this list,
     // starting at the position specified by index.
     // IndexOutOfBoundsException
   
public interface Iterator<E>
methods
boolean hasNext()
E    next()
void remove()
  // remove the last element
   
public interface ListIterator<E> extends Iterator<E>
methods
void add(E obj)
boolean hasNext()
boolean hasPrevious()
E next()
int nextIndex()
E previous()
int previousIndex()
void remove()
void set(E obj)

//iterator works with a LinkedList object
import java.util.*;

public class LinkedListAndIterator
{
    public static void main(String[] args)
    {
        LinkedList<Integer> intLList = new LinkedList<Integer>();
       
        Integer[] intArray = { 23, 12, 33, 89, 54, 9 ,77, 55, 8, 19, 30
                                                    ,15,62};
                                                   
        for(Integer num : intArray)
                intLList.add(num);
               
        System.out.println("line 10: intLList:\n" + "   ");
   
      print(intLList);
       
        ListIterator<Integer> listIt = intLList.ListIterator(0);
       
        System.out.println("line13: listIt points " + "to: " + listIt.next());
       
        System.out.println("line14: listIt points " + "to: " + listIt.next());
       
        listIt.set(999);
       
        System.out.println("line16: intLList " + "    ");
       
        print(intLList);
       
        listIt.add(1111);
       
        System.out.println("line19: after adding" + "1111 intLList:\n");
       
        print(intLList);
    }
   
    public static <T> void print(Collection<T> c)
    {
        for (T obj: c)
            System.out.print(obj + " ");
           
    }
}

LinkedList<Integer> intList = new LinkedList<Integer>();

Integer[] intArray = {23, 12, 33, 89, 54, 9 ,77,
                                            55, 8, 19, 30, 15, 62};
                                           
for (Integer num: intArray)
  intList.add(num);
   
ListIterator<Integer> listIt = intList.listIterator<0>

System.out.println(listIt.next());

listIt.set(999);

intList = {23, 999, 33, 89, 54, 9 ,77,
                                            55, 8, 19, 30, 15, 62};

listIt.add(1111);

intList = {23, 999, 1111, 33, 89, 54, 9 ,77,
                                            55, 8, 19, 30, 15, 62};


JAVA SERVER PROGRAMMING

Servlet container
init()
service()
destroy()

The Servlet API
javax.servlet and javax.servlet.http

Servlet Interface
public interface Servlet

javax.servlet.Servlet

when implementing Servlet interface, the following five methods must be implemented

init() method
service() method
destroy() method
getServletConfig() method
getServletInfo() method

public void init(ServlerConfig config) throws ServletException

public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException

public void destroy()

public ServletConfig gerServletConfig()

public String getServerInfo()

HttpServlet Class
HttpServlet class extends GenericServlet

service() method

  protected void service(HttpServletRequest req, HttpServletResponse res)                     throws ServletException, IOException
    public void service(ServletRequest req, ServletResponse res)
                throws ServletException, IOException
               
getLastModified() method

  protected long getLastModified(httpServletRequest req)

HttpServletRequest Interface

  public interface HttpServeltRequest extends ServletRequest
   
getParameter() method
  public String getParemeter(String key)

getParameterValues() method
    public String[] getParemeterValues(String key)
   
getParemetrNames() method
    public Enumeration getParameterNames()
   
HttpServletResponse Interface
    public interface HttpServletResponse extends ServletResponse
   
setContentType() method
    public void setConentType(String type)
   
getWriter() method
    public PrintWriter getWriter() throws IOException

getOutputSteam() method
    public ServletOutputStream getOutputStream() throws IOException
   
setHeader() method
    public void setHeader(String name String value)
   
//Import Servlet libraries
import javax.servlet.*;
import javax.servlet.http.*;

public class HelloWorld extends HttpServlet
{
    public void doGet(HttpServletRequest req, HttpServletResponse res)
                                trhows ServletException, IOException
    {
        res.setContentType("text/html");
        PrintWriter out = res.getWriter();
       
        out.println("<HTML>");
        out.println("<HEAD>");
        out.println("<TITLE>Hello World Sample Servlet</TITLE>");
        out.println("</HEAD>");
        out.println("<BODY>");
        out.println("CENTER><H1>Hello World!</H1></CENTER>");
        out.println("</BODY>");
        out.ptintln("</HTML>");
       
        out.close();
    }
}

Processig Form Data and Sending Email

Gathering Form Data

String message, msgForm, msgTo, msgSubject;

private void getParemeters(HttpServletRequest req)
        throws ServletException, IOException
{
    StringBuffer tempStringBuffer = new StringBuffer(1024);
   
    msgSubject = "Tech Support Request";
    msgTo = "tech@mail.com";
   
    msgFrom = req.getParameter("txtEmail");
    tempStringBuffer.append("From: ");
    tempStringBuffer.append("req.getParameter("txtFirst"));
    tempStringBuffer.append(" ");
    tempStringBuffer.append("req.getParameter("txtLast"));
    tempStringBuffer.append("\n");
    tempStringBuffer.append("Phone: ");
    tempStringBuffer.append("req.getParameter("txtPhone"));
    tempStringBuffer.append("\n");
    tempStringBuffer.append("Email:");
    tempStringBuffer.append("req.getParameter("txtEmail"));
    tempStringBuffer.append("\n\n");
    tempStringBuffer.append("Software: ");
    tempStringBuffer.append("reg.getParameter("ddlb_software"));
    tempStringBuffer.append("\n");
    tempStringBuffer.append("OS :");
    tempStringBuffer.append("reg.getParameter("ddlb_os"));
    tempStringBuffer.append("\n\n");
    tempStringBuffer.append("Problem: ");
    tempStringBuffer.append("req.getParameter("txtProblem"));
    tempStringBuffer.append("\n");
   
    message = tempStringBuffer.toString();
}

Send email using SmtpClient

private boolean sendMail()
{
  PrintStream out;
    SmtpClient send;
   
    try
    {
        send = new SmptClient("mail.xyz.com");
        send.from(msgForm);
        send.to(msgTo);
       
        out = send.startMessage();
       
        out.println("From : " + msgForm);
        out.println("To: " + msgTo);
        out.println("Subject: " + msgSubject);
       
        out.println("\n--------------\n");
        out.println(message);
        out.println("\n--------------\n");
        out.flush();
        out.close();
        send.closeServer();
    }
    catch (IOException e) {
      log("Error occurred while sending email", e);
        return false;
    }
    return true;
}

put all this together

import javax.servlet.*;
import javax.servlet.http.*;

import java.io.*;
import java.util.*;

import sun.net.smtp.SmtpClient;

import com.wrox.util.*;

public class techsupport extends HttpServlet
{
    String message, msgForm, msgTo, msgSubject;
   
    public void doPost(HttpServletRequest req, HttpSerlvetResponse res)
        throws ServletException, IOException
    {
        res.setContentType("text/html");
        PrintWriter out = res.getWriter();
        getParameters(req);
       
        if(!sendMail())
        {
            res.sendError(res.SC_INTERNAL_SERVER_ERROR, "An error ocurred while attemptiong to access the mail server.");
            return;
        }
        //Send acknowledgemenbt to the browser
        HTML h = new HTML("XYZ Corporation IT Department");
        h.add(HTML.HEADING, "your request has been submitted", false);
        out.println(h.getPage());
        out.close();
    }
   
    private void getParameters(HttpServletRequest req)
            throws ServletException, IOException
    {
        StringBuffer tempStringBuffer = new StringBuffer(1024);
        ....
    }
   
    private boolean sendMail()
    {
      PrintStream out;
        SmtpClient  send;
       
        try{
        ...
        }
        ...
    }
}

J2EE Indice de Temas

Java and J2EE Indice de Temas

j2EE Architecture -Containers
    Component Contracts
    Container Service APIs
    Declarative Services
   
J2EE Technologies
    Web Components
    Enterprise JavaBeans Components
   Service Technologies
        JDBC
        Java Transaction API and Service
        JNDI
    Communication Protocols
        Internet Protocols
        Remote Object Protocols
        JMS
        JavaMail
    XML
   
Distributed Computing Using RMI
    RMI Architecture
    The Stub and Skeleton Layer
        Stubs
        Skeletons
    The Remote Reference Layer
    The Transpor Layer
    Locating Remote Objects
    RMI Exceptions
    Developing Applications with RMI
    The RMI Security Manager
    Parameter Passing in RMI
    The Distributed Garbage Collector
    Dynamically Loading Classes
    Remote Callbacks
   
    Object Activation
    Custom Sockets and SSL
    RMI over IIOP (Internet inter-Orb Protocol)
   
Database Programming with JDBC
    Database drivers
    JDBC DataSources
    Connectin Pooling
    Distribuited Transactions
    RowSets
   
JNDI and LDAP
    Naming and Directory Services
    LDAP
    Introducing JNDI
   
XML Documents
    DTD and XML schema
    DTD, Parsers and Validation
    XML Namespaces
    Styling XML with CSS

XML Parsing with DOM and SAX
    SAX, JAXP, and a Simple Example

Introduction to Web Containers
    the HTTP Protocol
    HTTP Request Methods
        The GET Request Method
        The POST Request Method
    HTTP Response
    Web Containers and Web Applications
    Java Servlets
    Java Server Pages
    Deployment Descriptors
   
Servlet Programming
    Servlet Implementation
    init() method
    service() method
    destroy() method
    getServletConfig() method
    getServletInfo()
    GenericServlet Class
    SingleThreadModel Interface
    HttpServlet Class
    service() methods
    doXXX() methods
    getLastModified() method
Servlet Configuration
    ServletConfig Interface
    getInitParameters() method
    getInitParameterNames() method
    getServletContext() method
    getServletName() method
    obtainig a Reference to ServletConfig
   
Servlet Exceptions
    ServletException Class
    UnavailableException Class

Serlvet Lifecycle
   Instantiation
    Initialization
    Service
    Destroy
   
API for Request and Responses
    ServletRequest Interface, methods for parameters, attributes, inputs
    HTTPServletRequest Interface
        methods for request Path and URL
        methods for HTTP Header
        getMethod()
    ServletResponse Interface
        methods for Content Type and Length, Output, buffered Output
    HTTPServletResponse Interface
        methods for Error Handling
        sendRedirect() method
       
Servlet Sessions, Context and Collaboration

    Statelessness and Sessions
    Approaches to Session Tracking
        URL Rewriting
        Hidden Form Fields
        Cookies
    Session Tracking with the Java Servlet API
        Session Creation and Tracking
        The HttpSession Interface
            Methods for Session Lifetime
            Demonstrating Session Lifecycle with Cookies
            Session Lifecycle Without Cookies
            Methods for Managing States
            Demonstating State Management
        Binding and Unbinding Objects to and from Sessions
            The HttpSessionBindingListener Interface
            The HttpSessionBindingEvent Class
        A Simple Shopping Cart Using Sessions
            The Catalog Servlet
            The ShoppingCart Servlet
   
    Servlet Context
        The ServletContext Interface
        A Chat Application Using Context and Sessions
        The ChatRoom Class
        The ChatEntry Class
        The Administration Servlet
        Servlet for Chatting
        Chat Setup
       
    Servlet Collaboration
        Servlet Chaining
        Request Dispatching
            RequestDispatch Interface
           
Web Deployment, Authentication and Packaging
    Structure of a Web Application
        Directory Structure
        Web Archives Files
    Mapping Request to Application and Servlets
    Security Web Application
    Deployment Configuration
   
JSP Basics and Architecture
    JSP Directives
        The page Directives
        The include Directives
        The tablib Directive
    Scripting Elements
        Declarations
        Scriplets
        Expressions
    Standard Actions
        <jsp:useBean>
        <jsp:setProperty>
        <jsp:getProperty>
        <jsp:param>
        <jsp:include>
        <jsp:forward>
        <jsp:plugin>
    Implicit Objects
        The request Object
        The response Object
        The pageContext Object
        The session Object
        The application Object
        The out Object
        The config Object
        The page Object
    Scope
        Page Scope
        Request Scope
        Session Scope
        Application Scope
    XML Equivalent Tags
        DTD and Root Element
        Directives
        Scripting Elements
        Actions
       
    JSP Design Basic
        Page-Centric or Client-Server Design
        Page-View
        Page-View with Bean
    The 'Dispatcher' Approach
        Mediator-View
        Mediator-Composite View
        Service to Workers
       
    JSP Tag Extensions
        Tag Extension
            A Simple Tag
        Anatomy of a Tag Extension
            Tag Handlers
                javax.servlet.jsp.tagext.Tag Interface
                javax.servlet.jsp.tagext.BodyTag Interface
                javax.servlet.jsp.tagext.BodyContent Class
                Convenience Classes
                javax.servlet.jsp.tagext.TagExtraInfo Class
                Objects available to Tag Handlers
            Tag Library Descriptors
            Using Tag Extensions in JSP Pages
            Deploying and Packaging Tag Libraries
                No Packaging, WAR, The Library JAR
                Combination of WAR and JAR
        Writing Tag Extensions
            Processing Attributes
            Body Content
            Tags Introducing Scripting Variables
                Specifying a TagExtraInfo Class
                Implementing the TagExtraInfo Class
                Change to the Tag Handler
            Body Tags
                Body Tags and Iteration
                Body Tags and Filter Their Content
            Tag Nesting
            Handling Errors
           
    Advanced Custom JSP Tags
        An XSL Style Tag
        Swing Model Tags
            Using the Swing ListModel
            Creating a Name-Value Mapping Model
            Using the Swing TableModel
   
    Writing Maintainable JSP Pages
        JSP in a Multi-Tier Architecture
        Techniques for Writing Maintainable JSP
            Request Controller Architecture
                Implementing, when Not to use a
            Using includes in JSP
                Two Types of Includes
                using Static Includes
            Using JSP Beans
                Pages Beans
                Session Beans
                Application Beans
                Bean Configuration
            Using Tag Extensions
                Categories of Tags
                Model Tags
                Translation Tags
                Tags as Application Building Blocks
            Handling Iteration
            Handling Conditional Logic
            Using Styled XML
            When to use Custom SuperClasses for JSPs
            Standard Abstractions for Common Objects
            Handling Exceptions
            Internationalization
           
        Documenting the JSP layer
        Coding Standards for Maintainable JSPs
        The DBExplorer Application
            Requirements, Design, Implementation
                Presentation Tier, Data Tier
            Reviewing tha Application
            Deploying the Application
   
    JSP and XML - Working together
        JSP and XML
            Modular Design and Modular Reading
        A Profiled Newsletter - A Case Study
            An Overview of the Main Components
        The Configuration Component
            The Reflection Package
            The Constructor Class
            Invoking methods
        A Config File Example
            Meaning of Tags, Attributes
        The Java Code for XML Configuration
            Config Classified
            The Control Pattern of Config()
            configChild() and Methods Invocation
        The Database Component
            DBConnector and its Default Implementation
            QueryHandler
            ResultSetParser
            UserDataHandler
        XML Data Access Component
            DomSearch Queries
            DomSearch Output
            Instantiating DomSearch - DSNextMatch
            Configuration XML data for DOMSearch
            using DomSearch During a Session
        The Presentation Component
            The Login Page
            The Main Frames Pages and Initialization
            Control and Data Frames
        The Control Component
            The StampPageFactory Bean
           
    An XML-Based JDBC Connector Servlet Framework
        Implementing the JDBC Connector Servlet
        Using the JDBC Connector Servlet
       
    JavaMail
        Setup Instructions
        the JavaMail API
            javax.mail.Session
            javax.mail.Authenticator and PasswordAuthentication
            javax.mail.Message
            javax.mail.Part
            javax.mail.Multipart and BodyPart
            javax.mail.internet.MimePart
            javax.mail.internet.MimeMultipart and MimeBodyPart
            javax.mail.Service
            javax.mail.Transport
            javax.mail.Store
            javax.mail.Folder
        javax.mail.search.*
       
    EJB Architecture and Design
       Enterprise JavaBeans vs. JavaBeans
        What Are EJBs?
            varities of Beans. why use it?
        The EJB Container and Its Services
            Persistence
            Declarative Transactions
            Data Caching
            Declarative Security
            Error Handling
            Component Framework for Business Logic
            Scalability and Fail-Over
            Portability
            Manageability
        How the Container Provides Services
            Contarcts, Services, Interposition
        Working with EJBs
           The Client Developer´s View
            The Bean Programmer´s View
            What you Can´t Do in an EJB Component
        EJB Components on the Web
        Client-Tier Access to the EJBs
        Design of the EJB Tier
            UML Use Cases
            Analysis vs Implementation
            An Example of EJB Design
           
    Session Beans and Business Logic
        Session Bean and State
            Representing Business Logic
            The Difficult Problem of Conversational State
            Session Beans and Persistent Storage
        The Financial Aid Calculator Bean
        Implementing out Manufacturing Application
       
    Entity Beans and Persistence
        Why not Use Session Beans?
            Using a Stateful Session Bean
            Using a Stateless Session Bean
            Benefits of Entity Beans
        Container-vs. Bean-Managed Persistence
   
    EJB Container Services
        Transactions
            Transactions Without a Container
            Declaretive Semantics for Transactions
                Transactin Attibutes NotSupported, Supports, RequiresNew,
                Required, Mandatory, Never
            User-Controlled Transactions
            Isolation Levels
            Long Transactions
                Optimistic, Pesimistic Locking.
        Security
            Specifying the Security Requirements
                Security Roles, Method Permissions
            Programmatic Access Control
            Security and Application Design
        Exceptions
       
    Develop and Deployment Roles
   
    Enterprise JavaBeans 2.0
        Container-Managed Persistence in EJB 2.0
        The EJB 2.0 Query Language
        Message-Driven Beans
       
    Design Considerations for J2EE Applications
   
    Performance and Scalability
   
    Debugging Java Server Applications
   
    Unit Testing J2EE Applications
   
    The Java Message Service
        JMS programming
       
    Integration with CORBA
        IDL Types