How to Change the Border of a JFrame in Java

In this tutorial, we are going to see how to change the border of a JFrame in Java. You can draw borders around an undecorated JFrame. Just get the root panel of the JFrame and set its borders with the method setBorder(Border border).
 

 
First remove the frame decoration:

frame.setUndecorated(true);

Then draw the border:

frame.getRootPane().setBorder(
        BorderFactory.createMatteBorder(4, 4, 4, 4, Color.BLUE)
);

 
 

Java Program to Change the Border of a JFrame:

import java.awt.*;
import javax.swing.*;

public class BorderFrameExample extends JFrame 
{
   JLabel l = new JLabel("Welcome to StackHowTo!", JLabel.CENTER);
   
   public BorderFrameExample() {
      //add label to frame
      add(l, BorderLayout.CENTER);
      //remove the decoration
      setUndecorated(true);
      //set border
      getRootPane().setBorder(
         BorderFactory.createMatteBorder(4, 4, 4, 4, Color.BLUE)
      );
      setSize(250,250);
      setVisible(true);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   }
   public static void main(String[] args) {
      new BorderFrameExample();
   }
}

Output:

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