compAdd c1 = new compAdd();
///////////////compAdd.java
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
 
public class compAdd extends JFrame
{
  public JButton button = new JButton("Add");
  public JTextField txt1, txt2, txt3;
  public compAdd(String title)
  {
  super(title);
  txt1 = new JTextField(5);
  txt2 = new JTextField(5);
  txt3 = new JTextField(5);
  this.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
  JPanel cen = new JPanel();
  cen.add(txt1);
  cen.add(txt2);
  cen.add(txt3);
  cen.add(button);
  Container contentPane = this.getContentPane();
  contentPane.add(cen, BorderLayout.CENTER);
  addMe am = new addMe(this);
  button.addActionListener(am);
  }
 
  public static void main(String [] args)
  {
    JFrame f = new compAdd("Addtion");
    f.setSize(400,400);
    f.setVisible(true);
  }
}
 
//////////////addMe.java
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
 
public class addMe implements ActionListener
{
  private Container container;
  public addMe(JFrame c)
  {
    container = c.getContentPane();
  }
  public void actionPerformed(ActionEvent ae)
  {
 
    String label = ae.getActionCommand();
    if (label == "Add")
    {
      int txt1,txt2,txt3;
      compAdd c1 = new compAdd();
      txt1 = Integer.parseInt(c1.txt1.getText());
      txt2 = Integer.parseInt(c1.txt2.getText());
      txt3 = txt1 + txt2;
      c1.txt3.setText(String.valueOf(txt3));
    }
  }
}

compAdd c1 = new compAdd();

compAdd c1 = new compAdd("some String");