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Message.java Applet that reads customization parameters from an HTML file [ More in this category ] [Add your comments]

*******************
Message.java Applet that reads customization parameters from an HTML file
*******************
import java.applet.Applet;
import java.awt.*;

****************
 
public class Message extends Applet {
  private int fontSize;
  private String message;
  
  public void init() {
    setBackground(Color.black);
    setForeground(Color.white);
    
    // Base font size on window height.
    fontSize = getSize().height - 10;
    
    setFont(new Font("SansSerif", Font.BOLD, fontSize));

    // Read heading message from PARAM entry in HTML.
    message = getParameter("MESSAGE");
  }

  public void paint(Graphics g) {
    if (message != null) {
      g.drawString(message, 5, fontSize+5);
    }
  }
}
*******************

HelloWWW.java Basic Hello World (Wide Web) Applet [ More in this category ] [Add your comments]

*********************
import java.applet.Applet;
import java.awt.*;

*********************
 
public class HelloWWW extends Applet {
  private int fontSize = 40;
  
  public void init() {
    setBackground(Color.black);
    setForeground(Color.white);
    setFont(new Font("SansSerif", Font.BOLD, fontSize));
  }
  
  public void paint(Graphics g) {
    g.drawString("Hello, World Wide Web.", 5, fontSize+5);
  }
}
<<<<<<<<<<<<<<<<<<<<<

Application that reports all command-line arguments [ More in this category ] [Add your comments]

******************
ShowArgs.java Application that reports all command-line arguments.
******************
 */

public class ShowArgs {
  public static void main(String[] args) {
    for(int i=0; i

					

Basic Hello World application [ More in this category ]  [Add your comments] 




						
*******************
HelloWorld.java Basic Hello World application. 
*******************
 */

public class HelloWorld {
 public static void main(String[] args) {
    System.out.println("Hello, world.");
  }
}
/*


					

Statics.java Demonstrates static and non-static methods. [ More in this category ]  [Add your comments] 




						
 
*/

public class Statics {
 public static void main(String[] args) {
    staticMethod();
    Statics s1 = new Statics();
    s1.regularMethod();
  }

  public static void staticMethod() {
    System.out.println("This is a static method.");
  }

  public void regularMethod() {
    System.out.println("This is a regular method.");
  }
}


					

Example demonstrating the use of packages [ More in this category ]  [Add your comments] 




						
&&&&&&&&&&&&&&&&&&&
Example demonstrating the use of packages.

    * Class1.java defined in package1.
    * Class2.java defined in package2.
    * Class3.java defined in package2.package3.
    * Class1.java defined in package4.
    * PackageExample.java Driver for package example
&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~
Class1.java defined in package1.
~~~~~~~~~~~~~~~~~~~~~
package package1;

*****************
 
public class Class1 {
  public static void printInfo() {
    System.out.println("This is Class1 in package1.");
  }
}
&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~
Class2.java defined in package2. 
~~~~~~~~~~~~~~~~~~~~~
package package2;
$$$$$$$$$$$$$$$$

public class Class2 {
  public static void printInfo() {
    System.out.println("This is Class2 in package2.");
  }
}
&&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~~
Class3.java defined in package2.package3
~~~~~~~~~~~~~~~~~~~~~~
package package2.package3;

@@@@@@@@@@@@@@@@@@@@@@@@@

public class Class3 {
  public static void printInfo() {
    System.out.println("This is Class3 in " +
                       "package2.package3.");
  }
}
&&&&&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~~~~~
Class1.java defined in package4.
~~~~~~~~~~~~~~~~~~~~~~~~~
package package4;

@@@@@@@@@@@@@@@@

public class Class1 {
  public static void printInfo() {
    System.out.println("This is Class1 in package4.");
  }
}
&&&&&&&&&&&&&&&&&&&&&&&&&&
~~~~~~~~~~~~~~~~~~~~~~~~~~
PackageExample.java Driver for package example.
~~~~~~~~~~~~~~~~~~~~~~~~~~
import package1.*;
import package2.Class2;
import package2.package3.*;

***************************

public class PackageExample {
  public static void main(String[] args) {
    Class1.printInfo();
    Class2.printInfo();
    Class3.printInfo();
    package4.Class1.printInfo();
  }
}
****************************


					

Example illustrating inheritance and abstract classes [ More in this category ]  [Add your comments] 




						
***********************************
# Example illustrating inheritance and abstract classes.

    * Shape.java The parent class (abstract) for all closed, open, curved, and straight-edged shapes.
    * Curve.java An (abstract) curved Shape (open or closed).
    * StraightEdgedShape.java A Shape with straight edges (open or closed).
    * Measurable.java Interface defining classes with measurable areas.
    * Circle.java A circle that extends Shape and implements Measurable.
    * MeasureUtil.java Operates on Measurable instances.
    * Polygon.java A closed Shape with straight edges; extends StraightEdgedShape and implements Measurable.
    * Rectangle.java A rectangle that satisfies the Measurable interface; extends Polygon.
    * MeasureTest.java Driver for example.
**************************************
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Shape.java 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/** The parent class for all closed, open, curved, and 
 *  straight-edged shapes.
 *
 ############################
public abstract class Shape {
  protected int x, y;

  public int getX() {
    return(x);
  }

  public void setX(int x) {
    this.x = x;
  }

  public int getY() {
    return(y);
  }

  public void setY(int y) {
    this.y = y;
  }
}
#############################
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Curve.java An (abstract) curved Shape (open or closed)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/** A curved shape (open or closed). Subclasses will include
 *  arcs and circles.
 *
***********************

public abstract class Curve extends Shape {}
##############################
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
StraightEdgedShape.java A Shape with straight edges (open or closed). 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/** A Shape with straight edges (open or closed). Subclasses
 *  will include Line, LineSegment, LinkedLineSegments,
 *  and Polygon.
 *
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
public abstract class StraightEdgedShape extends Shape {}
################################
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Measurable.java Interface defining classes with measurable areas
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/** Used in classes with measurable areas. 
 *
 **************

public interface Measurable {
  double getArea();
}
#################################
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Circle.java A circle that extends Shape and implements Measurable.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/** A circle. Since you can calculate the area of
 *  circles, class implements the Measurable interface.
 *
***********************************
public class Circle extends Curve implements Measurable {
  private double radius;

  public Circle(int x, int y, double radius) {
    setX(x);
    setY(y);
    setRadius(radius);
  }

  public double getRadius() {
    return(radius);
  }

  public void setRadius(double radius) {
    this.radius = radius;
  }

  /** Required for Measurable interface. */

  public double getArea() {
    return(Math.PI * radius * radius);
  }
}
############################
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MeasureUtil.java Operates on Measurable instances
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/** Some operations on Measurable instances. 
 *

************************
public class MeasureUtil {
  public static double maxArea(Measurable m1,
                               Measurable m2) {
    return(Math.max(m1.getArea(), m2.getArea()));
  }

  public static double totalArea(Measurable[] mArray) {
    double total = 0;
    for(int i=0; i
~~~~~~~~~~~~~~~~~~~~~~


					

Code examples for interfaces [ More in this category ]  [Add your comments] 




						
****************************
Code examples for interfaces:

    * Class1.java implements Interface1.java
    * Abstract Class2.java implements Interface1.java and Interface2.java
    * Class3.java extends abstract class Class2.java
    * Interface3.java extends Interface1.java and Interface2.java
***************************
~~~~~~~~~~~~~~~~~~~~~~~~~~~
Class1.java 
~~~~~~~~~~~~~~~~~~~~~~~~~~~

// This class is not abstract, so it must provide 
// implementations of method1 and method2.

public class Class1 extends SomeClass
                    implements Interface1 {
  public ReturnType1 method1(ArgType1 arg) {
    someCodeHere();
    ...
  }
                      
  public ReturnType2 method2(ArgType2 arg) {
        someCodeHere();
    ...
  }

  ...
}
>>>>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~
Interface1.java
~~~~~~~~~~~~~~~~~~~~~~~~~~
public interface Interface1 {
   ReturnType1 method1(ArgType1 arg);
  ReturnType2 method2(ArgType2 arg);
}
>>>>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~~~~~
Abstract Class2.java implements Interface1.java and Interface2.java
~~~~~~~~~~~~~~~~~~~~~~~~~~
Class2.java 
~~~~~~~~~~~~~~~~~~~~~~~~~~

// This class is abstract, so does not have to provide
// implementations of the methods of Interface 1 and 2.

public abstract class Class2 extends SomeOtherClass
                             implements Interface1,
                                        Interface2 {
  ...
}
>>>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~~~~
Interface2.java
~~~~~~~~~~~~~~~~~~~~~~~~~

public interface Interface2 {
  ReturnType3 method3(ArgType3 arg);
}
~~~~~~~~~~~~~~~~~~~~~~~~~
# Class3.java extends abstract class Class2.java 
~~~~~~~~~~~~~~~~~~~~~~~~~
Class3.java
>>>>>>>>>>>>>>>>>>>>>>>>>

// This class is not abstract, so it must provide
// implementations of method1, method2, and method3.

public class Class3 extends Class2 {
  public ReturnType1 method1(ArgType1 arg) {
    someCodeHere();
    ...
  }
                      
  public ReturnType2 method2(ArgType2 arg) {
       someCodeHere();
    ...
  }

  public ReturnType3 method3(ArgType3 arg) {
     someCodeHere();
    ...
  }

  ...
}
>>>>>>>>>>>>>>>>>>>>>>>
# Interface3.java extends Interface1.java and Interface2.java
>>>>>>>>>>>>>>>>>>>>>>>
~~~~~~~~~~~~~~~~~~~~~~
Interface3.java 
~~~~~~~~~~~~~~~~~~~~~~

// This interface has three methods (by inheritance) and 
// two constants.

public interface Interface3 extends Interface1,
                                    Interface2 {
  int MIN_VALUE = 0;
  int MAX_VALUE = 1000;
}
<<<<<<<<<<<<<<<<<<<<<



					

Speedboat.java Illustrates inheritance from Ship class [ More in this category ]  [Add your comments] 




						
*****************************
Speedboat.java Illustrates inheritance from Ship class. See SpeedboatTest.java for a test.
*****************************
/** A fast Ship. Red and going 20 knots by default. 
 *
 ***********************
public class Speedboat extends Ship {
  private String color = "red";

  /** Builds a red Speedboat going N at 20 knots. */
  
  public Speedboat(String name) {
    super(name);
    setSpeed(20);
  }

  /** Builds a speedboat with specified parameters. */
  
  public Speedboat(double x, double y, double speed,
                   double direction, String name,
                   String color) {
    super(x, y, speed, direction, name);
    setColor(color);
  }

  /** Report location. Override version from Ship. */
  
  public void printLocation() {
    System.out.print(getColor().toUpperCase() + " ");
    super.printLocation();
  }
  
  /** Gets the Speedboat's color. */
  
  public String getColor() {
    return(color);
  }

  /** Sets the Speedboat's color. */
  
  public void setColor(String colorName) {
    color = colorName;
  }
}
**********************
SpeedboatTest.java 
**********************
/** Try a couple of Speedboats and a regular Ship. 
 *
*****************************

public class SpeedboatTest {
  public static void main(String[] args) {
    Speedboat s1 = new Speedboat("Speedboat1");
    Speedboat s2 = new Speedboat(0.0, 0.0, 2.0, 135.0,
                                 "Speedboat2", "blue");
    Ship s3 = new Ship(0.0, 0.0, 2.0, 135.0, "Ship1");
    s1.move();
    s2.move();
    s3.move();
    s1.printLocation();
    s2.printLocation();
    s3.printLocation();
  }
}
*****************************


					

A Ship class illustrating object-oriented programming concepts [ More in this category ]  [Add your comments] 




						
************************
Ship.java A Ship class illustrating object-oriented programming concepts. Incorporates Javadoc comments. See ShipTest.java for a test. 
************************
/** Ship example to demonstrate OOP in Java.
 *
 *  @author 
 *          Larry Brown
 *  @version 2.0
 */

public class Ship {
  // Instance variables

  private double x=0.0, y=0.0, speed=1.0, direction=0.0;
  private String name;

  // Constructors

  /** Build a ship with specified parameters. */

  public Ship(double x, double y, double speed,
              double direction, String name) {
    setX(x);
    setY(y);
    setSpeed(speed);
    setDirection(direction);
    setName(name);
  }

  /** Build a ship with default values
   *  (x=0, y=0, speed=1.0, direction=0.0).
   */

  public Ship(String name) {
    setName(name);
  }

  /** Move ship one step at current speed/direction. */

  public void move() {
    moveInternal(1);
  }

  /** Move N steps. */

  public void move(int steps) {
    moveInternal(steps);
  }

  private void moveInternal(int steps) {
    double angle = degreesToRadians(direction);
    x = x + (double)steps * speed * Math.cos(angle);
    y = y + (double)steps * speed * Math.sin(angle);
  }

  private double degreesToRadians(double degrees) {
    return(degrees * Math.PI / 180.0);
  }

  /** Report location to standard output. */

  public void printLocation() {
    System.out.println(getName() + " is at (" + getX() +
                       "," + getY() + ").");
  }

  /** Get current X location. */

  public double getX() {
    return(x);
  }

  /** Set current X location. */

  public void setX(double x) {
    this.x = x;
  }

  /** Get current Y location. */

  public double getY() {
    return(y);
  }

  /** Set current Y location. */

  public void setY(double y) {
    this.y = y;
  }

  /** Get current speed. */

  public double getSpeed() {
    return(speed);
  }

  /** Set current speed. */

  public void setSpeed(double speed) {
    this.speed = speed;
  }

  /** Get current heading (0=East, 90=North, 180=West,
   *  270=South).  I.e., uses standard math angles, not
   *  nautical system where 0=North, 90=East, etc.
   */

  public double getDirection() {
    return(direction);
  }

  /** Set current direction (0=East, 90=North, 180=West,
   *  270=South). I.e., uses standard math angles,not
   *  nautical system where 0=North,90=East, etc.
   */

  public void setDirection(double direction) {
    this.direction = direction;
  }

  /** Get Ship's name. Can't be modified by user. */

  public String getName() {
    return(name);
  }

  private void setName(String name) {
    this.name = name;
  }
}
*********************
ShipTest.java 
*********************
public class ShipTest {
 public static void main(String[] args) {
    Ship s1 = new Ship("Ship1"); 
    Ship s2 = new Ship(0.0, 0.0, 2.0, 135.0, "Ship2");
    s1.move();
    s2.move(3);
    s1.printLocation();
    s2.printLocation();
  }
}


					


  
  
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