Question

So I have 3 JFrames. JFrame 1 (aka opts) is for inputting some variables. On OK, it creates JFrame 2 (aka view, a graphical viewing Frame). In the constructor, JFrame 3 (aka manager, for cycling through the graphical views) is created instantly.
I want them to be Windows-alike decorated with JFrame.setDefaultLookAndFeelDecorated(true) (from now on referred to as “it”).

A few differtent cases:

1. When I don’t set it at all, all JFrames are Windows decorated.
2. When I put it in the “opts” or “manager” constructor, run the project, and click the OK button, all JFrames are Windows-alike decorated.
3. However, when I put it in the “view” constructor, only “opts” and “view” are Windows decorated, but “manager” is Java decorated.
4. But when I put it in a class which does nothing more than read some data from a file, and make some objects out of it, only “opts” is Windows decorated.

How exactly does it work? I want to know why it happens as it happens.

Edit: I can’t reproduct case 4, but still, some things happen that I don’t understand. Try commenting out some of the “it”s. It’ll give some strange results.

package test;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

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

public class Frame1 extends JFrame {
  public Frame1() {
    JFrame.setDefaultLookAndFeelDecorated(true);
      Frame1.setOptions(this);
      JButton b1 = new JButton("hi");
      b1.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
          makeFrame2(2);
        }
      });
      this.add(b1);
    }

    public void makeFrame2(int x) {
      this.dispose();
      new Frame2(x);
    }

    public static void setOptions(JFrame f) {
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.setSize(250, 250);
      f.setEnabled(true);
      f.setVisible(true);
    }

    public static void main(String[] args) {
      new Frame1();
    }
}

package test;

import javax.swing.JFrame;

public class Frame3 extends JFrame {
  Frame2 link;
  SomeClass sc;

  public Frame3(Frame2 link)  {
    JFrame.setDefaultLookAndFeelDecorated(true);
    Frame1.setOptions(this);
    this.link = link;
    sc = new SomeClass(25);
  }
}

package test;

import javax.swing.JFrame;

public class SomeClass {
  int x;

  public SomeClass(int x) {
    JFrame.setDefaultLookAndFeelDecorated(true);
    this.x = x;
  }
}

package test;

import javax.swing.JFrame;

public class Frame2 extends JFrame {
  public Frame2(int x) {
    JFrame.setDefaultLookAndFeelDecorated(true);
    Frame1.setOptions(this);
    new Frame3(this);
  }
}

Answer 1

According to the oracle java documentation, setDefaultLookAndFeelDecorated changes the parameter for all newly created JFrames, all existing JFrames are unchanged.

JFrame Documentation