How to Make a windows application (jframe) full size

Question

I am trying to create a windows application project. That time I am using some code for the full screen but it can't set. how to solve this problem.

JFrame frame = new JFrame();
frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 
frame.setUndecorated(true);
frame.setVisible(true); 

 public Login() {
        initComponents();
       JFrame frame = new JFrame();
        frame.setExtendedState(JFrame.MAXIMIZED_BOTH); 
       frame.setUndecorated(true);
        frame.setVisible(true); 
    }

output comes but has some bugs.

Answer 1

Finally, I got the answer to the problem.

public Login() {
        initComponents();
        this.setExtendedState(JFrame.MAXIMIZED_BOTH); 
    }