Category Archives: java applets

java GUI - Snowman

Screen Shot 2014-09-09 at 10.13.27 PM

Original Code:

//********************************************************************
//  Snowman.java       Author: Lewis/Loftus/Cocking
//
//  Demonstrates basic drawing methods and the use of color.
//********************************************************************

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

public class Snowman extends Applet
{
   //-----------------------------------------------------------------
   //  Draws a snowman.
   //-----------------------------------------------------------------
   public void paint (Graphics page)
   {
      final int MID = 150;
      final int TOP = 50;

      setBackground (Color.cyan);

      page.setColor (Color.blue);
      page.fillRect (0, 175, 300, 50);  // ground

      page.setColor (Color.yellow);
      page.fillOval (-40, -40, 80, 80);  // sun

      page.setColor (Color.white);
      page.fillOval (MID-20, TOP, 40, 40);      // head
      page.fillOval (MID-35, TOP+35, 70, 50);   // upper torso
      page.fillOval (MID-50, TOP+80, 100, 60);  // lower torso

      page.setColor (Color.black);
      page.fillOval (MID-10, TOP+10, 5, 5);   // left eye
      page.fillOval (MID+5, TOP+10, 5, 5);    // right eye

      page.drawArc (MID-10, TOP+20, 20, 10, 190, 160);   // smile

      page.drawLine (MID-25, TOP+60, MID-50, TOP+40);  // left arm
      page.drawLine (MID+25, TOP+60, MID+55, TOP+60);  // right arm

      page.drawLine (MID-20, TOP+5, MID+20, TOP+5);  // brim of hat
      page.fillRect (MID-15, TOP-20, 30, 25);        // top of hat
   }
}

 

 

 

cloud of points 

import java.awt.geom.Point2D;
import java.awt.geom.Ellipse2D;
import java.awt.Graphics2D;
import java.util.ArrayList;

/**
   This class draws a cloud of circles
*/
public class Cloud
{
   /**
      Construct a Cloud object
   */
   public Cloud()
   {
      points = new ArrayList();
   }
   
   /**
      Add a point to the array list
      @param aPoint the point to add
   */
   public void add(Point2D.Double aPoint)
   {
      points.add(aPoint);
   }
   
   /**
      Draws the cloud
      @param g2 the graphics context
   */
   public void draw(Graphics2D g2)
   {
      for (int i = 0; i < points.size(); i++)
      {
         Point2D.Double p = (Point2D.Double)points.get(i);
         
         Ellipse2D.Double e =
            new Ellipse2D.Double(p.getX(), p.getY(), RADIUS, RADIUS);         
            
         g2.draw(e);
      }
   }
   
   private ArrayList points;
   private final int RADIUS = 5;
}

/* Class Cloud:
1. Constructor creates an array list.
2. The method add takes a Point2D.Double as an argument and it adds it to the array list.
3. The method draw creates the points and uses g2.draw(aPoint). Note: a Point2D.Double can not be drawn. So, you should draw an Ellipse2D.Double with x and y from Point2D.Double.
4. Write a class that extends Applet or JApplet to draw a cloud's points by creating an object of Cloud and randomly generating the x and y coordinates. */



import javax.swing.JApplet;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.Random;
import java.awt.geom.Point2D;

/**
   This applet displays a cloud of circles
*/
public class ExP13_7JApplet extends JApplet
{
   public void paint(Graphics g)
   {
      Graphics2D g2 = (Graphics2D)g;

      Cloud c = new Cloud();
      
      Random generator = new Random();
      double x = 0;
      double y = 0;
      
      for (int i = 0; i < 20; i++)
      {
         x = 200 * generator.nextDouble();
         y = 200 * generator.nextDouble();         
         c.add(new Point2D.Double(x, y));
      }
      
      c.draw(g2);
   }
}

Java Applets: Frames and Panels

  • A frame is a container that is used to display GUI-based Java applications.
  • A frame is displayed as a separate window with its own title bar.
  • It can be repositioned on the screen and re-sized as needed by dragging it with the mouse.
  • It contains small buttons in the corner of the frame that allow the frame to be minimized, maximized, and closed.
  • A frame is defined by the JFrame class.
  • A panel is also a container. However, unlike a frame, it cannot be displayed on its own.
  • A panel must be added to another container for it to be displayed.
  • Generally a panel doesn’t move unless you move the container that it’s in.
  • Its primary role is to help organize the other components in a GUI.
  • A panel is defined by the JPanel class.

Java Applets: Components and Containers

  • A GUI component is an object that represents a screen element that is used to display information or to allow the user to interact with the program in a certain way.
  • A container is a special type of component that is used to hold and organize other components.
  • Frames and panels are two examples of Java containers.