If you are not clear with the program aim then scroll down and see the output and read again!

Declaring and Defining Array of components:

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

public class ColorChooserApplet extends Applet 
{
	Button btn = new Button("Run");
	Label lbl[] = new Label[3];
	Scrollbar sc[] = new Scrollbar[3];
	TextField tf[] = new TextField[3];
	String[] slbl = {"Red","Green","Blue"};
	public void init()
	{
		for(int i=0;i<3;i++)
		{
			lbl[i] = new Label(slbl[i]);	
			sc[i] = new Scrollbar(Scrollbar.HORIZONTAL, 0, 20, 0, 275);
			tf[i] = new  TextField("0");
			add(lbl[i]);
			add(sc[i]);
			add(tf[i]);
		}
		add(btn);
	}
}

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class ColorChooserApplet extends Applet 
{
	Button btn = new Button("Run");
	Label lbl[] = new Label[3];
	Scrollbar sc[] = new Scrollbar[3];
	TextField tf[] = new TextField[3];
	String[] slbl = {"Red","Green","Blue"};
	public void init()
	{
		setLayout(null);

		for(int i=0;i<3;i++)
		{
			lbl[i] = new Label(slbl[i]);	
			sc[i] = new Scrollbar(Scrollbar.HORIZONTAL, 0, 20, 0, 275);
			tf[i] = new  TextField("0");
			add(lbl[i]);
			add(sc[i]);
			add(tf[i]);
			lbl[i].setBounds(20,(75*i)+50, 50,30);
			sc[i].setBounds(70,(75*i)+50, 350,30);
			tf[i].setBounds(450,(75*i)+50, 50, 30);

		}
		add(btn);
		btn.setBounds(200,400,100,50);
	}
	
}

Code to sync Scrollbars and TextFields:
In our application, When user moves Scrollbar the current value of scroll bar is to be displayed/updated in text field and vice versa.

        public void adjustmentValueChanged(AdjustmentEvent e) 
        {
		for(int i=0;i<3;i++)
		{
			tf[i].setText(sc[i].getValue()+"");	
		}
			
        }
	 
        public void keyReleased(KeyEvent e) 
        {
		System.out.println("Release:"+tf[0].getText());

		for(int i=0;i<3;i++)
		{
			sc[i].setValue(Integer.parseInt(tf[i].getText()));	
		}
        }

Full Program:

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class ColorChooserApplet extends Applet implements AdjustmentListener, KeyListener, ActionListener, Runnable
{
	int r=0,g=0,b=0;
	Thread t;
	Button btn = new Button("Run");
	Label lbl[] = new Label[3];
	Scrollbar sc[] = new Scrollbar[3];
	TextField tf[] = new TextField[3];
	String[] slbl = {"Red","Green","Blue"};
	public void init()
	{
		setLayout(null);
		
		for(int i=0;i<3;i++)
		{
			lbl[i] = new Label(slbl[i]);	
			sc[i] = new Scrollbar(Scrollbar.HORIZONTAL, 0, 20, 0, 275);
			tf[i] = new  TextField("0");
			add(lbl[i]);
			add(sc[i]);
			add(tf[i]);
			lbl[i].setBounds(20,(75*i)+50, 50,30);
			sc[i].setBounds(70,(75*i)+50, 350,30);
			tf[i].setBounds(450,(75*i)+50, 50, 30);
			
			sc[i].addAdjustmentListener(this);
			tf[i].addKeyListener(this);
		}
		add(btn);
		btn.setBounds(200,400,100,50);
		btn.addActionListener(this);
	}
	public void adjustmentValueChanged(AdjustmentEvent e) 
	{
		for(int i=0;i<3;i++)
		{
			tf[i].setText(sc[i].getValue()+"");	
		}
			
	}
	public void	keyPressed(KeyEvent e)
	{
		System.out.println("Pressed:"+tf[0].getText());
		
	} 
    public void	keyReleased(KeyEvent e) 
	{
		System.out.println("Release:"+tf[0].getText());

		for(int i=0;i<3;i++)
		{
			sc[i].setValue(Integer.parseInt(tf[i].getText()));	
		}
	}
    public void	keyTyped(KeyEvent e)
	{
		System.out.println("Typed:"+tf[0].getText());

	} 
	public void actionPerformed(ActionEvent e)
	{
		r = sc[0].getValue();
		g = sc[1].getValue();
		b = sc[2].getValue();
		Color clr = new Color(r,g,b);	
		setBackground(clr);
		t = new Thread(this);
		t.start();
	}
	
	public void run()
	{
		try
		{
			for(int i=0;i<10;i++)
			{
				t.sleep(1000);
				r = r - sc[0].getValue()/10;
				g = g - sc[1].getValue()/10;
				b = b - sc[2].getValue()/10;
				Color clr = new Color(r,g,b);	
				setBackground(clr);			
			}
		}
		catch(Exception e)
		{
			System.out.println(e);
		}
		
	}
}

/*
<applet code="ColorChooserApplet" width="550" height="550"></applet>
*/

The post Color Chooser – multiple event handling appeared first on Ankit Virparia.

Five steps to be kept in mind when writing an applet program:

1. import java.applet.* (Need Applet class from java.applet package)

2. create a public class (Class name and File name must be same in case of public class)

3. extend the class from the base class Applet

4. do not write main method

5. write the applet life cycle methods (i.e.  init, start, stop, destroy, paint)

File name: abc.java

import java.applet.*;

public class abc extends Applet
{
}

Steps to compile and Run Applet program:

1. Compile your java code using javac.exe on console/command prompt.
2. To run the generated class file, we have to write <applet> tag in an additional file(e.g. run.txt). Later on that file name is to be passed as an argument to appletviewer.exe as shown below

File name: run.txt

<applet code="abc" width="500" height="500"></applet>

Commands to be executed: run.txt

c:> javac abc.java
c:> appletviewer run.txt

The post What is an Applet? appeared first on Ankit Virparia.

Example:

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

public class Myclass extends Applet 
{
    public void init() { }
    public void start() { }
    public void stop() {}
    public void destroy() {}
    public void paint(Graphics g) {}
}

public class MyClass 
{
public static void main(String args[]) {}
}    

The post Difference between Applet and Application appeared first on Ankit Virparia.

List of Methods:

1. public void init()
2. public void start()
3. public void stop()
4. public void destroy()
5. public void paint(Graphics g)

Which method will be invoked when?

init()

• Invoked only once
• Invoked when the application is launched using appletviewer or browser
• Should include code for component defination, Object creation, Layout settings, Basic look and feel

start()

• Invoked when application is maximized
• Default application state is Maximized window so this will also be invoked on launching
• Should include code for starting/resuming thread, starting/resuming Graphical User Interface, etc…

stop()

• Invoked when application is minimized
• invoked also when the window is terminated while its in maximizes state.
• Should include code for pausing/stopping thread, pausing/stopping Graphical User Interface, etc…

destroy()

• Invoked when application is about to terminate
• invoked when we close the application.
• Should include code for connection closing, file closing, etc…

paint()

• Invoked when application is to be refreshed in terms of GUI
• invoked when we start, move or resize applet.
• Should include code for GUI design

Some method calling scenarios:

On Launching an Applet application: init(), start(), paint()

On Minimizing an Applet application: stop()

On Maximizing an Applet application: start(), paint()

On Moving/Re-sizing an Applet application: paint(), paint(), …, paint()

On Terminating an Applet application: stop(), destroy()

The post Applet Life Cycle appeared first on Ankit Virparia.

Writing a String on Applet

File Name: WriteString.java

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

public class WriteString extends Applet
{
	public void paint(Graphics g)
	{
		g.drawString("Ankit Virparia - www.ankit.co", 100, 100);	
	}	
}
/*
<applet code="WriteString" width="500" height="200"></applet>
*/

Output:

Changing Text Font

We need to invoke a method named: setFont(Font f) to change the Font size and style. To create a Font object we have used a constructor which takes following arguments. 1) String FontName, 2) Font Style as int. Here, We have used Font.BOLD whereby BOLD is the static int which belongs to java.awt.Font class. 3) Font size as int.

To change Text Color we have to invoke a method named: setColor(Color c) of Graphics class. Color object can be passed in 2 ways
1. By Creating Color object from the scratch like Color clr = new Color(255,0,0); Here, Constructor takes red, green, blue int values which can vary from 0 to 255.
2. By Passing static color object Like Color.RED or Color.red

File Name: FontString.java

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

public class FontString extends Applet
{
	public void paint(Graphics g)
	{
		Font f = new Font("Arial", Font.BOLD, 36);
		g.setFont(f);
		g.setColor(Color.GREEN);
		g.drawString("Ankit Virparia, www.ankit.co", 10, 100); 	
	}	
}
/*
<applet code="FontString" width="500" height="200"></applet>
*/

Output:

Drawing Shapes

File Name: ShapeApplet.java

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

public class ShapeApplet extends Applet
{
	public void paint(Graphics g)
	{
		setBackground(Color.BLACK);    //setting background as BLACK
		g.setColor(new Color(255,255,255));
		g.drawLine(10, 10, 400, 10);  //g.drawLine(x1, y1, x2, y2);   	
		g.setColor(Color.red);
		g.drawRect(30,30,200,100);    //g.drawRect(x, y, w, h);
		g.setColor(new Color(80,10,124));
		g.drawOval(30,30,200,100);    //g.drawOval(x, y, w, h);
		g.setColor(Color.BLUE);
		g.drawArc(100, 20, 300, 300, 0, 90);    //g.drawArc(x, y, w, h, Starting Angle, Further Angle);
	}	
}
/*
<applet code="ShapeApplet" width="500" height="200"></applet>
*/

Output:

Filling Shapes

File Name: ShapeFillApplet.java

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

public class ShapeFillApplet extends Applet
{
	public void paint(Graphics g)
	{
		setBackground(Color.BLACK);    //setting background as BLACK
		g.setColor(new Color(255,255,255));
		g.drawLine(10, 10, 400, 10);  //g.drawLine(x1, y1, x2, y2);   	
		g.setColor(Color.red);
		g.fillRect(30,30,200,100);    //g.fillRect(x, y, w, h);
		g.setColor(new Color(80,10,124));
		g.fillOval(30,30,200,100);    //g.fillOval(x, y, w, h);
		g.setColor(Color.BLUE);
		g.fillArc(100, 20, 300, 300, 0, 90);    //g.fillArc(x, y, w, h, Starting Angle, Further Angle);
	}	
}
/*
<applet code="ShapeFillApplet" width="500" height="200"></applet>
*/

Output:

Drawing Polygon

File Name: DrawingPolygons.java

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

public class DrawingPolygons extends Applet
{
  public void paint(Graphics g)
  {
    int x[] = { 70, 150, 190, 80, 100 };
    int y[] = { 80, 110, 160, 190, 100 };
    g.drawPolygon (x, y, 5);
 
    int x1[] = { 210, 280, 330, 210, 230 };
    int y1[] = { 70, 110, 160, 190, 100 };
    g.fillPolygon (x1, y1, 5);
  }
}
/*
<applet code="DrawingPolygons" width="500" height="200"></applet>
*/

Output:

The post Shapes and Colors in Applet appeared first on Ankit Virparia.

Write an applet that draws four Vertical bars of equal size & of different colors such that they cover up the whole applet area. The applet should operate correctly even if it is resized.

Code:

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

public class equalBars extends Applet
{
	Color[] clr = {Color.red, Color.green, Color.pink, Color.blue};
	int cnt = 0;
	public void init()
	{
		setBackground(Color.black);	
	}
	
	public void paint(Graphics g)
	{
		int w = getWidth();
		int h = getHeight();
		
		for(int i=0;i<4;i++)
		{
			g.setColor(clr[i]);
			g.fillRect(w/4*i,0,w/4,h);
		}
	}	
	
}

/*
<applet code="equalBars" width="500" height="500"></applet>
*/

Output:

The post Colorful Equal Bars appeared first on Ankit Virparia.

For Example,

This is Demo.
his is Demo.T
is is Demo.Th
…

How to write program for this?

1. We need applet first. Will follow the applet life cycle

   import java.applet.*;
   import java.awt.*;
   
   public class bannerDemo extends Applet
   {
   	public void init()
   	{
   	}
   	public void paint(Graphics g)
   	{
   	}		
   }
   /*
   <applet code="bannerDemo" width="500" height="150"></applet>
   */
   

2. We want to draw a String on applet area. Which can be done by calling drawString() method of Graphics class inside paint() method.

   	public void paint(Graphics g)
   	{
   		Font f = new Font("Arial",Font.BOLD,36);
   		g.setFont(f);
   		g.drawString("Ankit Virparia (ankit.co)",50,75);
   	}	
   

3. We want continuous change in the text which we have printed so, Will go for multithreading.

   public class bannerDemo extends Applet implements Runnable
   {
   	Thread t;
           public void run()
   	{}
   }
   

4. Here one extra thread will be given a responsibility to update the text given (which is stored in a global variable – I mean common between paint() and run() methods)

   public class bannerDemo extends Applet implements Runnable
   {
   	Thread t;
   	String msg = "Ankit Virparia (ankit.co)";
   	
   	public void run()
   	{
   		try
   		{
   			while(true)
   			{
   				t.sleep(1000);
   				char c = msg.charAt(0);
   				String tmp = msg.substring(1,msg.length());
   				msg = tmp + c;
   				repaint();
   			}
   		}
   		catch(Exception e)
   		{
   			System.out.println(e);	
   		}
   	}
   		
   	public void paint(Graphics g)
   	{
   		Font f = new Font("Arial",Font.BOLD,36);
   		g.setFont(f);
   		g.drawString(msg,50,75);
   	}	
   	
   }
   

5. We need to start the thread in the beginning. Which can be written in init() method.

   	Thread t;
   	public void init()
   	{
   		t = new Thread(this);
   		t.start();
   	}
   

6. paint() is invoked only when a user does GUI related change. But here in our case we want to invoke paint() at the interval of 1 second.

7. We are ready to go!

Program for Banner Applet

File Name:bannerDemo.java

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

public class bannerDemo extends Applet implements Runnable
{
	Thread t;
	String msg = "Ankit Virparia (ankit.co)";
	public void init()
	{
		t = new Thread(this);
		t.start();
	}
	
	public void run()
	{
		try
		{
			while(true)
			{
				t.sleep(1000);
				char c = msg.charAt(0);
				String tmp = msg.substring(1,msg.length());
				msg = tmp + c;
				repaint();
			}
		}
		catch(Exception e)
		{
			System.out.println(e);	
		}
	}
		
	public void paint(Graphics g)
	{
		Font f = new Font("Arial",Font.BOLD,36);
		g.setFont(f);
		g.drawString(msg,50,75);
	}	
	
}

/*
<applet code="bannerDemo" width="500" height="150"></applet>
*/

The post Banner Applet appeared first on Ankit Virparia.

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

public class toonApplet extends Applet
{
	int y = 200;
	public void init()
	{	
		setBackground(Color.YELLOW);
	}
	
	public void stop()	
	{
		if(y==200)y = 50;
		else y = 200;
	}
	
	public void paint(Graphics g)
	{
		g.drawOval(200,50,100,100);
		g.drawRect(50,150,400,50);

		g.drawRect(50,y,50,100);
		g.drawRect(400,y,50,100);

		g.drawRect(150,200,200,300);

		g.drawRect(150,500,50,100);
		g.drawRect(300,500,50,100);
	}
}
/*
<applet code="toonApplet" width="500" height="700"></applet>
*/

The post Cartoon Character – Moving Hands appeared first on Ankit Virparia.

Its’s built-in platform-independent windowing, graphics, and user-interface widget toolkit. The java.awt is now part of the Java Foundation Classes (JFC). Which can be used for a graphical user interface (GUI) for a Java program. AWT consists of many classes which can be said: Components. A component is a class which can create a event specific GUI like TextField, Button, Label, Checkbox, TextArea, etc…

To add any component in Applet area, We have to call a add(Component c) method of Applet class. Which is discussed briefly in the below example.

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

public class componentDemo extends Applet
{
	Button b;
	Label l;
	TextField tf;
	Scrollbar sb;
	TextArea ta;
	Checkbox c1,c2,c3;
	CheckboxGroup cbg = new CheckboxGroup();
	public void init()
	{
		tf = new TextField("Ankit",20);
		l = new Label("First Name:");
		b = new Button("Okay!");
		ta = new TextArea(7,40);
		sb = new Scrollbar(Scrollbar.VERTICAL, 100, 20, 0, 200);
		sb.setPreferredSize(new Dimension(30,200));
		c1 = new Checkbox("Cricket",true,cbg);
		c2 = new Checkbox("Hockey",false,cbg);
		c3 = new Checkbox("Football",false,cbg);
		add(l);
		add(tf);
		add(b);
		add(sb);
		add(ta);
		add(c1);
		add(c2);
		add(c3);
	}	
}

/*
<applet code="componentDemo" width="500" height="500"></applet>
*/

Output:

The post Basic AWT components appeared first on Ankit Virparia.