JFrame 在使用按钮创建后不绘画

Question

I want to have titlescreen and open a game by clicking a button. When i call the play()-method of my project normally, it draws the first level. But when i call it with a button, a white screen appeares and I dont know why. Here is a code snippet:

package com.company;

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class Game implements ActionListener {
    private String csvFile;
    private JFrame titlescreen;
    private JButton startButton;

public Game(String csvFile){
    this.csvFile = csvFile;
}

public void prepare(){
    titlescreen = new JFrame("Titlescreen");
    titlescreen.setSize(100,100);
    startButton = new JButton("Start Game");
    startButton.addActionListener(this);

    titlescreen.add(startButton);
    titlescreen.setVisible(true);
}

public void play(){
    titlescreen.setVisible(false);
    if(csvFile!= null) {
        LevelBuilder levelBuilder = new LevelBuilder(csvFile, ";", ",");

        AllObstacles ao = new AllObstacles();
        ao.addObstaclesOfString(levelBuilder.getLvlString(), ";", ",");
        Goal g = new Goal(125, 125, 250, 250);
        PlayGame c = new PlayGame(ao, g, levelBuilder);
        c.create();
        c.play();
    }
 }

@Override
public void actionPerformed(ActionEvent e) {
    startButton.dispatchEvent(e);
    play();
}
}

Can someone help me with my problem?

Answer 1

Please see you have play() method used inside of play() method. Please try to change ones name. Maybe you are just calling wrong method inside of actionPerformed() method.

If that won't work, you can try deleting whole play(){...} and actionPerformed(){...} methods from your snippet and delete line:

startButton.addActionListener(this);

Then you can just add this into your prepare() function:

startButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if(csvFile!= null) {
                   titlescreen.dispose();
                   LevelBuilder levelBuilder = new LevelBuilder(csvFile, ";", ",");
                   AllObstacles ao = new AllObstacles();
                   ao.addObstaclesOfString(levelBuilder.getLvlString(), ";", ",");
                   Goal g = new Goal(125, 125, 250, 250);
                   SwingUtilities.invokeLater(() -> new PlayGame(ao, g, levelBuilder);
            }
        });

It will add to your button new ActionListener that:

• disposes titlescreen (you do not need it running in background)
• runs new PlayGame object in new thread (to avoid lags especially if you have any timer in your game)

Moreover:

c.create()
c.play()

you are using those two methods everytime you create new PlayGame object, so you should put them into constructor of PlayGame class, so:

public PlayGame(){
//your current code
create();
play();
}