How to execute code in a method/constructor after the execution of the method/constructor is finished

To execute certain code after all the other code in the same method/constructor has been executed, you need to create a new thread  and make the new thread to wait util the parent thread finishes execution.

Following is an example.

import java.awt.Component;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.util.ArrayList;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;

public class FocusTest extends JFrame {
    JTextField f1 = null;
    JButton b1 = null;

    public FocusTest() {
        getContentPane().setLayout(new GridLayout(2,2));
        JLabel label1 = new JLabel("Input 1: ");
        f1 = new JTextField(15);
        b1 = new JButton("button 1");
     
        add(label1);
        add(f1);
        add(b1);
     
        ArrayList<Component> tp = new ArrayList<Component>();
        tp.add(f1);
        tp.add(b1);
     
        //the following code will not work
        //because the layout of button 1 is not realized
        //b1.requestFocusInWindow();
     
        //request focus on button 1
        //after all the other code in the constructor is executed.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
           public void run() {
               b1.requestFocusInWindow();
           }
        });
     
        b1.addActionListener(new ButtonListener());
        f1.addFocusListener(new F1FocusListener());
     
        b1.setEnabled(false);
     
        pack();
        setVisible(true);
    }
 
    private class F1FocusListener extends FocusAdapter {
        public void focusGained(FocusEvent e){
            if (e.getSource().equals(f1)){
             
                //because button 1 is disabled
                //the following code will do nothing
                //b1.doClick();
             
                //will programmatically click button 1
                //after all the other code in the method is executed.
                javax.swing.SwingUtilities.invokeLater(new Runnable() {
                    public void run() {
                        b1.doClick();
                    }
                });
             
                b1.setEnabled(true);
            }
        }
    }
 
    private class ButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent e){
            if (e.getSource() == b1){
                f1.setText("Excellent job!!!!");
            }
        }
    }
 
    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new FocusTest();
            }
        }
        );
    }
}

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