Launcher wont open my JFrame

Question

I'm trying to open one of my classes that involve a JFrame using a simple launcher:

public class Launcher {

public static void main(String[] args) {

    new StartScreen();

   }

}

This launcher is meant to launch the class:

import javax.swing.JFrame;
import javax.swing.*;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.*;
import java.awt.image.BufferedImage;

public class StartScreen extends JFrame {
private static JFrame frame;
GameKeyboard GK;

boolean gamePlay = false;
boolean gameQuit = false;
boolean gameTwoPlayer = false;
String option;

//set dimension of window and buttons
public final int screenWidth = 800; // Width of window
public final int screenHeight = screenWidth / 12 * 9; // Height of window

private static Graphics gr;

//store images
private static Image background;
private static Image play;
private static Image twoPlayer;
private static Image quit;
private static Image playSelected;
private static Image twoPlayerSelected;
private static Image quitSelected;

public void StartScreen() {
    frame = new JFrame();
    setSize(screenWidth, screenHeight);
    frame.add(this, BorderLayout.CENTER);
    //         frame.pack();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);
    frame.setResizable(false);
    frame.setTitle("Space Wars Menu");
    frame.setLocationRelativeTo(null);
    getContentPane().setLayout(null);

    BufferedImage canvas=new BufferedImage(920,720,BufferedImage.TYPE_INT_ARGB);

    gr=canvas.getGraphics();

    JLabel label=new JLabel(new ImageIcon(canvas));
    frame.add(label);

    MenuKeyboard.initialise();

    //load images
    background = GameImage.loadImage("Images//background.jpg");
    play = GameImage.loadImage("Images//play.png");
    playSelected = GameImage.loadImage("Images//playSelected.png");
    twoPlayer = GameImage.loadImage("Images//twoPlayer.png");
    twoPlayerSelected = GameImage.loadImage("Images//twoPlayerSelected.png");
    quit = GameImage.loadImage("Images//quit.png");
    quitSelected = GameImage.loadImage("Images//quit.png");


    //draw images
    gr.drawImage(background, 0, 0, null);
    gr.drawImage(playSelected, 160, -50, null);
    gr.drawImage(twoPlayer, 160, 150, null);
    gr.drawImage(quit, 160, 250, null);

    int specialKey = MenuKeyboard.getSpecialKey();
    while(gamePlay == false)
    {

        if (MenuKeyboard.getSpecialKey() == 40) //if down pressed
        {
            gr.drawImage(twoPlayerSelected, 160, 150, null);
            gr.drawImage(play, 160, -50, null);
          }

      }

   }
}

The class is not finished yet obviously but I was just testing if it would open up a window and load all the images, but no window even gets opened.. despite the classes actually being linked. Any help?

Answer 1

Your constructor is in reality a method with a constructor name.

You should switch from this:

public void StartScreen() {
    // Code
}

to this:

public StartScreen() {
    // Code
}

Answer 2

Your while loop runs continuously which is stepping on the Swing event thread effectively freezing it and preventing Swing from drawing anything. Solution: get rid of that while loop.

Instead use Key Bindings to trap specific key presses. If you need a game loop, use a Swing Timer.

Tutorials:

• Overall Swing Tutorials
• Key Bindings
• Swing Timer
• Concurrency in Swing

---

Edit

Your StartScreen class has no constructor. Get rid of the void return type in your pseudo constructor.

Other issues:

• You should not use null layouts.
• Most of your variables should not be static.