How to Make a Calculator in Java Using Swing

Program

import javax.swing.*;
import java.awt.event.*;
 
 
class Calc implements ActionListener
{
	JFrame f;
	JTextField t;
	JButton b1,b2,b3,b4,b5,b6,b7,b8,b9,b0,bdiv,bmul,bsub,badd,bdec,beq,bdel,bclr;
 
	static double a=0,b=0,result=0;
	static int operator=0;
 
	Calc()
	{
		f=new JFrame("Calculator");
		t=new JTextField();
		b1=new JButton("1");
		b2=new JButton("2");
		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("9");
		b0=new JButton("0");
		bdiv=new JButton("/");
		bmul=new JButton("*");
		bsub=new JButton("-");
		badd=new JButton("+");
		bdec=new JButton(".");
		beq=new JButton("=");
		bdel=new JButton("Delete");
		bclr=new JButton("Clear");
		
		t.setBounds(30,40,280,30);
		b7.setBounds(40,100,50,40);
		b8.setBounds(110,100,50,40);
		b9.setBounds(180,100,50,40);
		bdiv.setBounds(250,100,50,40);
		
		b4.setBounds(40,170,50,40);
		b5.setBounds(110,170,50,40);
		b6.setBounds(180,170,50,40);
		bmul.setBounds(250,170,50,40);
		
		b1.setBounds(40,240,50,40);
		b2.setBounds(110,240,50,40);
		b3.setBounds(180,240,50,40);
		bsub.setBounds(250,240,50,40);
		
		bdec.setBounds(40,310,50,40);
		b0.setBounds(110,310,50,40);
		beq.setBounds(180,310,50,40);
		badd.setBounds(250,310,50,40);
		
		bdel.setBounds(60,380,100,40);
		bclr.setBounds(180,380,100,40);
		
		f.add(t);
		f.add(b7);
		f.add(b8);
		f.add(b9);
		f.add(bdiv);
		f.add(b4);
		f.add(b5);
		f.add(b6);
		f.add(bmul);
		f.add(b1);
		f.add(b2);
		f.add(b3);
		f.add(bsub);
		f.add(bdec);
		f.add(b0);
		f.add(beq);
		f.add(badd);
		f.add(bdel);
		f.add(bclr);
		
		f.setLayout(null);
		f.setVisible(true);
		f.setSize(350,500);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		f.setResizable(false);
		
		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);
		b0.addActionListener(this);
		badd.addActionListener(this);
		bdiv.addActionListener(this);
		bmul.addActionListener(this);
		bsub.addActionListener(this);
		bdec.addActionListener(this);
		beq.addActionListener(this);
		bdel.addActionListener(this);
		bclr.addActionListener(this);
	}
 
	public void actionPerformed(ActionEvent e)
	{
		if(e.getSource()==b1)
			t.setText(t.getText().concat("1"));
		
		if(e.getSource()==b2)
			t.setText(t.getText().concat("2"));
		
		if(e.getSource()==b3)
			t.setText(t.getText().concat("3"));
		
		if(e.getSource()==b4)
			t.setText(t.getText().concat("4"));
		
		if(e.getSource()==b5)
			t.setText(t.getText().concat("5"));
		
		if(e.getSource()==b6)
			t.setText(t.getText().concat("6"));
		
		if(e.getSource()==b7)
			t.setText(t.getText().concat("7"));
		
		if(e.getSource()==b8)
			t.setText(t.getText().concat("8"));
		
		if(e.getSource()==b9)
			t.setText(t.getText().concat("9"));
		
		if(e.getSource()==b0)
			t.setText(t.getText().concat("0"));
		
		if(e.getSource()==bdec)
			t.setText(t.getText().concat("."));
		
		if(e.getSource()==badd)
		{
			a=Double.parseDouble(t.getText());
			operator=1;
			t.setText("");
		} 
		
		if(e.getSource()==bsub)
		{
			a=Double.parseDouble(t.getText());
			operator=2;
			t.setText("");
		}
		
		if(e.getSource()==bmul)
		{
			a=Double.parseDouble(t.getText());
			operator=3;
			t.setText("");
		}
		
		if(e.getSource()==bdiv)
		{
			a=Double.parseDouble(t.getText());
			operator=4;
			t.setText("");
		}
		
		if(e.getSource()==beq)
		{
			b=Double.parseDouble(t.getText());
		
			switch(operator)
			{
				case 1: result=a+b;
					break;
		
				case 2: result=a-b;
					break;
		
				case 3: result=a*b;
					break;
		
				case 4: result=a/b;
					break;
		
				default: result=0;
			}
		
			t.setText(""+result);
		}
		
		if(e.getSource()==bclr)
			t.setText("");
		
		if(e.getSource()==bdel)
		{
			String s=t.getText();
			t.setText("");
			for(int i=0;i<s.length()-1;i++)
			t.setText(t.getText()+s.charAt(i));
		}		
	}
 
	public static void main(String...s)
	{
		new Calc();
	}
}

Output