Main.java Source code

Introduction

Here is the source code for Main.java

Source

import java.awt.Component;
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.FocusTraversalPolicy;
import java.awt.KeyboardFocusManager;

import javax.swing.JButton;
import javax.swing.JFrame;

public class Main {
    public static void main(String[] argv) {
        JFrame frame = new JFrame();
        JButton component1 = new JButton("1");
        JButton component2 = new JButton("2");
        JButton component3 = new JButton("3");

        frame.setLayout(new FlowLayout());
        frame.add(component1);
        frame.add(component2);
        frame.add(component3);

        frame.pack();
        frame.setVisible(true);

        System.out.println(findPrevFocus().getName());
    }

    public static Component findPrevFocus() {
        Component c = KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
        Container root = c.getFocusCycleRootAncestor();

        FocusTraversalPolicy policy = root.getFocusTraversalPolicy();
        Component prevFocus = policy.getComponentBefore(root, c);
        if (prevFocus == null) {
            prevFocus = policy.getDefaultComponent(root);
        }
        return prevFocus;
    }
}