We can remove the existing layout by calling a method: setLayout(null); and then even if we try to components, that will not be displayed. To make component visible we need to invoke seBounds(x_cord, y_cord, width, height) method on all the components.

Program:

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

public class NullLayoutDemo extends Applet
{
	Button b1, b2, b3;
	public void init()
	{
		setBackground(Color.green);
		setLayout(null);
		
		b1 = new Button("Button1");
		b2 = new Button("Button2");
		b3 = new Button("Button3");
		
		add(b1);
		add(b2);
		add(b3);
		
		b1.setBounds(50,100, 150, 50);
		b2.setBounds(50,200, 150, 50);
		b3.setBounds(50,300, 150, 50);
	}	
}
/*
<applet code="NullLayoutDemo" width="500" height="500"></applet>
*/

Output:

The post Custom Layout or null Layout appeared first on Ankit Virparia.

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.