import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class Main {
	static String number1="0";
	static String number2="0";
	static String oper="";
	public static void main(String[] args) {
		// TODO Auto-generated method stub
      JFrame m=new JFrame();
      m.setSize(300, 400);
      JPanel panelMain = new JPanel();
      m.add(panelMain);
      panelMain.setLayout(new GridLayout(2,1));
      JLabel l1=new JLabel("0");
      panelMain.add(l1);
      JPanel panelB=new JPanel();
      panelMain.add(panelB);
      panelB.setLayout(new GridLayout(5,5));
      JButton b1=new JButton("1");
      panelB.add(b1);
      b1.addActionListener(new ActionListener() {

		@Override
		public void actionPerformed(ActionEvent arg0) {
			// TODO Auto-generated method stub
			number1+="1";
			l1.setText(number1);
			
		}});
      JButton b2=new JButton("2");
      panelB.add(b2);
      b2.addActionListener(new ActionListener() {

  		@Override
  		public void actionPerformed(ActionEvent arg0) {
  			// TODO Auto-generated method stub
  			number1+="2";
			l1.setText(number1);
  		}});
      JButton bp=new JButton("+");
      panelB.add(bp);
      bp.addActionListener(new ActionListener() {

  		@Override
  		public void actionPerformed(ActionEvent arg0) {
  			// TODO Auto-generated method stub
  			number2=number1;
  			number1="";
  			l1.setText(number1);
  			oper="plus";
  		}});
      JButton br=new JButton("=");
      panelB.add(br);
      br.addActionListener(new ActionListener() {

  		@Override
  		public void actionPerformed(ActionEvent arg0) {
  			// TODO Auto-generated method stub
  			double x=Double.parseDouble(number2);
  			double y=Double.parseDouble(number1);
  			if(oper.equals("plus")) l1.setText(x+y+"");
  			
  			
  		}});
      
      
      m.setVisible(true);
      m.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

}