import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
import javax.swing.JButton;

public class Text
{
    private JFrame frame;
    private JTextField textField;
    private JButton button;

    public void go()
    {
        frame = new JFrame();
        textField = new JTextField();
        button = new JButton("button");

        frame.add(textField, BorderLayout.NORTH);
        frame.add(button, BorderLayout.CENTER);

        button.addActionListener(new ButtonListener());

        frame.pack();
        frame.setVisible(true);
    }
    public void setText(String str){
        textField.setText(str);
    }

    public static void main(String[] args)
    {
        Text t = new Text();
        t.go();
    }
    private class ButtonListener implements ActionListener{

        @Override
        public void actionPerformed(ActionEvent e)
        {
            setText(e.getActionCommand());
        }
    }
}