Puzzle Game in Java

//Puzzle Game using Swing//
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class puzzle extends JFrame implements ActionListener{
JButton b1,b2,b3,b4,b5,b6,b7,b8,b9,next;
puzzle(){
super("Puzzle Game - JavaTpoint");
 b1=new JButton("1");
 b2=new JButton(" ");
 b3=new JButton("3");
 b4=new JButton("4");
 b5=new JButton("5");
 b6=new JButton("6");
 b7=new JButton("7");
 b8=new JButton("8");
 b9=new JButton("2");
 next=new JButton("next");

b1.setBounds(10,30,50,40);
b2.setBounds(70,30,50,40);
b3.setBounds(130,30,50,40);
b4.setBounds(10,80,50,40);
b5.setBounds(70,80,50,40);
b6.setBounds(130,80,50,40);
b7.setBounds(10,130,50,40);
b8.setBounds(70,130,50,40);
b9.setBounds(130,130,50,40);
next.setBounds(70,200,100,40);

add(b1);add(b2);add(b3);add(b4);add(b5);add(b6);add(b7);add(b8);add(b9); add(next);
b1.addActionListener(this);
b2.addActionListener(this);
b3.addActionListener(this);
b4.addActionListener(this);
b5.addActionListener(this);
b6.addActionListener(this);
b7.addActionListener(this);
b8.addActionListener(this);
b9.addActionListener(this);
next.addActionListener(this);

next.setBackground(Color.black);
next.setForeground(Color.green);
setSize(250,300);
setLayout(null);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
//end of constructor//
public void actionPerformed(ActionEvent e){
if(e.getSource()==next){
String s=b4.getLabel();
b4.setLabel(b9.getLabel());
b9.setLabel(s);
s=b1.getLabel();
b1.setLabel(b5.getLabel());
b5.setLabel(s);
s=b2.getLabel();
b2.setLabel(b7.getLabel());
b7.setLabel(s);
}
if(e.getSource()==b1){
String s=b1.getLabel();
if(b2.getLabel().equals(" ")){ b2.setLabel(s); b1.setLabel(" ");}
else if(b4.getLabel().equals(" ")){ b4.setLabel(s); b1.setLabel(" ");}
 }
//end of if//
if(e.getSource()==b3){
String s=b3.getLabel();
if(b2.getLabel().equals(" ")){ b2.setLabel(s); b3.setLabel(" ");}
else if(b6.getLabel().equals(" ")){ b6.setLabel(s); b3.setLabel(" ");}
 }
//end of if//
if(e.getSource()==b2){
String s=b2.getLabel();
if(b1.getLabel().equals(" ")){ b1.setLabel(s); b2.setLabel(" ");}
else if(b3.getLabel().equals(" ")){ b3.setLabel(s); b2.setLabel(" ");}
else if(b5.getLabel().equals(" ")){ b5.setLabel(s); b2.setLabel(" ");}
 }
//end of if//
if(e.getSource()==b4){
String s=b4.getLabel();
if(b1.getLabel().equals(" ")){ b1.setLabel(s); b4.setLabel(" ");}
else if(b7.getLabel().equals(" ")){ b7.setLabel(s); b4.setLabel(" ");}
else if(b5.getLabel().equals(" ")){ b5.setLabel(s); b4.setLabel(" ");}
 }
//end of if//
if(e.getSource()==b5){
String s=b5.getLabel();
if(b2.getLabel().equals(" ")){ b2.setLabel(s); b5.setLabel(" ");}
else if(b4.getLabel().equals(" ")){ b4.setLabel(s); b5.setLabel(" ");}
else if(b6.getLabel().equals(" ")){ b6.setLabel(s); b5.setLabel(" ");}
else if(b8.getLabel().equals(" ")){ b8.setLabel(s); b5.setLabel(" ");}
 }
//end of if//
if(e.getSource()==b6){

String s=b6.getLabel();
if(b9.getLabel().equals(" ")){ b9.setLabel(s); b6.setLabel(" ");}
else if(b3.getLabel().equals(" ")){ b3.setLabel(s); b6.setLabel(" ");}
else if(b5.getLabel().equals(" ")){ b5.setLabel(s); b6.setLabel(" ");}

 }
//end of if//
if(e.getSource()==b7){
String s=b7.getLabel();
if(b4.getLabel().equals(" ")){ b4.setLabel(s); b7.setLabel(" ");}
else if(b8.getLabel().equals(" ")){ b8.setLabel(s); b7.setLabel(" ");}

 }
//end of if  //

if(e.getSource()==b8){
String s=b8.getLabel();
if(b7.getLabel().equals(" ")){ b7.setLabel(s); b8.setLabel(" ");}
else if(b9.getLabel().equals(" ")){ b9.setLabel(s); b8.setLabel(" ");}
else if(b5.getLabel().equals(" ")){ b5.setLabel(s); b8.setLabel(" ");}

 }
//end of if//

if(e.getSource()==b9){
String s=b9.getLabel();
if(b6.getLabel().equals(" ")){ b6.setLabel(s); b9.setLabel(" ");}
else if(b8.getLabel().equals(" ")){ b8.setLabel(s); b9.setLabel(" ");}

if(b1.getLabel().equals("1")&&b2.getLabel().equals("2")&&b3.getLabel()
.equals("3")&&b4.getLabel().equals("4")&&b5.getLabel().equals("5")
&&b6.getLabel().equals("6")&&b7.getLabel().equals("7")&&b8.getLabel()
.equals("8")&&b9.getLabel().equals(" ")){
JOptionPane.showMessageDialog(puzzle.this,"!!!you won!!!");
}
 }
//end of if//

}
//end of actionPerformed//


public static void main(String[] args){
new puzzle();
}
//end of main//

}
//end of class//