JFrame仅打开关闭，最小化和调整大小按钮，直到调整窗口大小为止

Question

I'm making a game in Java and the game window doesn't open properly when i run the code. I can resize it and make it the right size, but that's kinda annoying to do every time.

Here's the code for the window and I also added a picture to show how the window opens.

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

public class Window extends Canvas {

    private static final long serialVersionUID = 573860602378245302L;

    public Window(int width, int height, String title, Game game){
        JFrame frame = new JFrame(title);

        frame.setPreferredSize(new Dimension(width, height));
        frame.setMaximumSize(new Dimension(width, height));
        frame.setMaximumSize(new Dimension(width, height));

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(true);
        frame.setLocationRelativeTo(null);
        frame.add(game);
        frame.setVisible(true);
        game.start();
    }
}

Answer 1

There are few ways you can make a JFrame of a particular size. frame.setPreferredSize() is NOT one of those ways.

You can call setSize(int width, int height) on JFrame like this:

import javax.swing.JFrame;

public class JFrameSize
{
  public static void main(String[] args)
  {
    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 300);
    frame.setVisible(true);
  }
}

Or you can set preferred size of the contents (a JPanel in below example) of JFrame and call pack() on JFrame like this:

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Dimension;

public class JFrameSize2
{
  public static void main(String[] args)
  {
    JPanel panel = new JPanel();
    panel.setPreferredSize(new Dimension(400, 300));

    JFrame frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().add(panel);
    frame.pack();
    frame.setVisible(true);
  }
}