JFrame method in java

The  code creates a window "Code sake" of 300 pixels by 300 pixels. The window won´t be visible until we call setVisible(true). If we don´t include the last line "frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE)", when we close the window the program won´t finish and will continue running.

package code.sake.window;
import javax.swing.JFrame;

public class Game {
 public static void main(String[] args) {
  JFrame frame = new JFrame("Code sake");
  frame.setSize(300, 300);
  frame.setVisible(true);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }
}

If we run it we will obtain: