Java Swing : JButton, JLabel

Java JButton

The JButton class is used to create a labeled button that has platform independent implementation. The application result in some action when the button is pushed. It inherits AbstractButton class.

JButton class declaration

Let's see the declaration for javax.swing.JButton class.

1. public class JButton extends AbstractButton implements Accessible  

Commonly used Constructors:

Constructor	Description
JButton()	It creates a button with no text and icon.
JButton(String s)	It creates a button with the specified text.
JButton(Icon i)	It creates a button with the specified icon object.

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Commonly used Methods of AbstractButton class:

Methods	Description
void setText(String s)	It is used to set specified text on button
String getText()	It is used to return the text of the button.
void setEnabled(boolean b)	It is used to enable or disable the button.
void setIcon(Icon b)	It is used to set the specified Icon on the button.
Icon getIcon()	It is used to get the Icon of the button.
void setMnemonic(int a)	It is used to set the mnemonic on the button.
void addActionListener(ActionListener a)	It is used to add the action listener to this object.

Java JButton Example

1. import javax.swing.*;    
2. public class ButtonExample {  
3. public static void main(String[] args) {  
4.     JFrame f=new JFrame("Button Example");  
5.     JButton b=new JButton("Click Here");  
6.     b.setBounds(50,100,95,30);  
7.     f.add(b);  
8.     f.setSize(400,400);  
9.     f.setLayout(null);  
10.     f.setVisible(true);   
11. }  
12. }  

Output:

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Java JButton Example with ActionListener

1. import java.awt.event.*;  
2. import javax.swing.*;    
3. public class ButtonExample {  
4. public static void main(String[] args) {  
5.     JFrame f=new JFrame("Button Example");  
6.     final JTextField tf=new JTextField();  
7.     tf.setBounds(50,50, 150,20);  
8.     JButton b=new JButton("Click Here");  
9.     b.setBounds(50,100,95,30);  
10.     b.addActionListener(new ActionListener(){  
11. public void actionPerformed(ActionEvent e){  
12.             tf.setText("Welcome to Javatpoint.");  
13.         }  
14.     });  
15.     f.add(b);f.add(tf);  
16.     f.setSize(400,400);  
17.     f.setLayout(null);  
18.     f.setVisible(true);   
19. }  
20. }  

Output:

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Example of displaying image on the button:

1. import javax.swing.*;      
2. public class ButtonExample{    
3. ButtonExample(){    
4. JFrame f=new JFrame("Button Example");            
5. JButton b=new JButton(new ImageIcon("D:\\icon.png"));    
6. b.setBounds(100,100,100, 40);    
7. f.add(b);    
8. f.setSize(300,400);    
9. f.setLayout(null);    
10. f.setVisible(true);    
11. f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);    
12.     }         
13. public static void main(String[] args) {    
14.     new ButtonExample();    
15. }    
16. }    

Output:

ava JLabel

The object of JLabel class is a component for placing text in a container. It is used to display a single line of read only text. The text can be changed by an application but a user cannot edit it directly. It inherits JComponent class.

JLabel class declaration

Let's see the declaration for javax.swing.JLabel class.

1. public class JLabel extends JComponent implements SwingConstants, Accessible  

Commonly used Constructors:

Constructor	Description
JLabel()	Creates a JLabel instance with no image and with an empty string for the title.
JLabel(String s)	Creates a JLabel instance with the specified text.
JLabel(Icon i)	Creates a JLabel instance with the specified image.
JLabel(String s, Icon i, int horizontalAlignment)	Creates a JLabel instance with the specified text, image, and horizontal alignment.

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Commonly used Methods:

Methods	Description
String getText()	t returns the text string that a label displays.
void setText(String text)	It defines the single line of text this component will display.
void setHorizontalAlignment(int alignment)	It sets the alignment of the label's contents along the X axis.
Icon getIcon()	It returns the graphic image that the label displays.
int getHorizontalAlignment()	It returns the alignment of the label's contents along the X axis.

Java JLabel Example

1. import javax.swing.*;  
2. class LabelExample  
3. {  
4. public static void main(String args[])  
5.     {  
6.     JFrame f= new JFrame("Label Example");  
7.     JLabel l1,l2;  
8.     l1=new JLabel("First Label.");  
9.     l1.setBounds(50,50, 100,30);  
10.     l2=new JLabel("Second Label.");  
11.     l2.setBounds(50,100, 100,30);  
12.     f.add(l1); f.add(l2);  
13.     f.setSize(300,300);  
14.     f.setLayout(null);  
15.     f.setVisible(true);  
16.     }  
17.     }  

Output:

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Java JLabel Example with ActionListener

1. import javax.swing.*;  
2. import java.awt.*;  
3. import java.awt.event.*;  
4. public class LabelExample extends Frame implements ActionListener{  
5.     JTextField tf; JLabel l; JButton b;  
6.     LabelExample(){  
7.         tf=new JTextField();  
8.         tf.setBounds(50,50, 150,20);  
9.         l=new JLabel();  
10.         l.setBounds(50,100, 250,20);      
11.         b=new JButton("Find IP");  
12.         b.setBounds(50,150,95,30);  
13.         b.addActionListener(this);    
14.         add(b);add(tf);add(l);    
15.         setSize(400,400);  
16.         setLayout(null);  
17.         setVisible(true);  
18.     }  
19.     public void actionPerformed(ActionEvent e) {  
20.         try{  
21.         String host=tf.getText();  
22.         String ip=java.net.InetAddress.getByName(host).getHostAddress();  
23.         l.setText("IP of "+host+" is: "+ip);  
24.         }catch(Exception ex){System.out.println(ex);}  
25.     }  
26.     public static void main(String[] args) {  
27.         new LabelExample();  
28.     } }  

Output:

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