如何从主方法调用中打开一个 Jframe

Question

我在java中下载了一个蛇游戏项目并尝试修改它。最初项目包含三个java文件 即“Engine.java”、“Snake.java”、“GameBoard.java”。而Engine.java 有main() 方法，当我运行这个Engine.java 类游戏开始运行。

为了提高用户对项目的迭代性，我创建了两个 JFrame：“PlayGame.java”、Rules.java

现在这个项目有五个 java 类 -

Engine.java(containing main() method) 
Snake.java
GameBoard.java
PlayGame.java(is a JFrame)
Rules.java(is a JFrame)

PlayGame.java have three buttons

Play - i want when play button get clicked snake game start/run.
Rules - when clicked Rules.java Jframe should be opened 
Exit - exits the application

现在我首先想要的是“PlayGame.java”JFrame 应该出现（并且这是作为游戏项目的主要输出出现）并抛出这个游戏应该开始，即当我点击来自PlayGame JFrame 的播放按钮时游戏应该开始 我面临的问题是当我单击play 按钮然后gamescreen 出现在窗口上但snake is not moving。

这是我在Play button 的actionPerformed() 方法中包含的代码

        private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

            JFrame frame = new JFrame("SnakeGame");
    frame.setVisible(true); 
            frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    frame.setResizable(true);
    Canvas canvas = new Canvas();
    canvas.setBackground(Color.black);
            canvas.setPreferredSize(new Dimension(GameBoard.MAP_SIZE * GameBoard.TILE_SIZE, GameBoard.MAP_SIZE * GameBoard.TILE_SIZE));
            frame.getContentPane().add(canvas); 
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
            new Engine(canvas).startGame();
}           

我还展示了startGame() 方法的代码，它在Engine.java 类中

public void startGame() {
    canvas.createBufferStrategy(2);

    Graphics2D g = (Graphics2D)canvas.getBufferStrategy().getDrawGraphics();
    g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

    long start = 0L;
    long sleepDuration = 0L;
    while(true) {
        start = System.currentTimeMillis();

        update();
        render(g);

        canvas.getBufferStrategy().show();

        g.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());

        sleepDuration = (1500L / UPDATES_PER_SECOND) - (System.currentTimeMillis() - start);

        if(sleepDuration > 0) {
            try {
                Thread.sleep(sleepDuration);
            } catch(Exception e) {
                e.printStackTrace();
            }
        }
    }
}

这里我还在我的问题中附加了 Engine.java 类和 PlayGame.java，以便更好地理解问题

Engine.java

package org.psnbtech;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import org.psnbtech.GameBoard.TileType;
import org.psnbtech.Snake.Direction;


public class Engine extends KeyAdapter {

    private static final int UPDATES_PER_SECOND = 15;

    private static final Font FONT_SMALL = new Font("Arial", Font.BOLD, 20);

    private static final Font FONT_LARGE = new Font("Arial", Font.BOLD, 40);

    public Canvas canvas;

    public GameBoard board;

    public Snake snake;

    public int score;

    public boolean gameOver;


    public Engine(Canvas canvas) {
                this.canvas = canvas;
            this.board = new GameBoard();
        this.snake = new Snake(board);

        resetGame();

        canvas.addKeyListener(this);
                //new Engine(canvas).startGame();
    }


    public void startGame() {
        canvas.createBufferStrategy(2);

        Graphics2D g = (Graphics2D)canvas.getBufferStrategy().getDrawGraphics();
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        long start = 0L;
        long sleepDuration = 0L;
        while(true) {
            start = System.currentTimeMillis();

            update();
            render(g);

            canvas.getBufferStrategy().show();

            g.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());

            sleepDuration = (1500L / UPDATES_PER_SECOND) - (System.currentTimeMillis() - start);

            if(sleepDuration > 0) {
                try {
                    Thread.sleep(sleepDuration);
                } catch(Exception e) {
                                    e.printStackTrace();
                }
            }
        }
    }

    public void update() {
        if(gameOver || !canvas.isFocusOwner()) {
            return;
        }
        TileType snakeTile = snake.updateSnake();
        if(snakeTile == null || snakeTile.equals(TileType.SNAKE)) {
            gameOver = true;
        } else if(snakeTile.equals(TileType.FRUIT)) {
            score += 10;
            spawnFruit();
        }
    }

    public void render(Graphics2D g) {
        board.draw(g);

        g.setColor(Color.WHITE);

        if(gameOver) {
            g.setFont(FONT_LARGE);
            String message = new String("Your Score: " + score);
            g.drawString(message, canvas.getWidth() / 2 - (g.getFontMetrics().stringWidth(message) / 2), 250);

            g.setFont(FONT_SMALL);
            message = new String("Press Enter to Restart the Game");
            g.drawString(message, canvas.getWidth() / 2 - (g.getFontMetrics().stringWidth(message) / 2), 350);
        } else {
            g.setFont(FONT_SMALL);
            g.drawString("Score:" + score, 10, 20);
        }
    }

    public void resetGame() {
        board.resetBoard();
        snake.resetSnake();
        score = 0;
        gameOver = false;
        spawnFruit();
    }

    public void spawnFruit() {
        int random = (int)(Math.random() * ((GameBoard.MAP_SIZE * GameBoard.MAP_SIZE) - snake.getSnakeLength())); // if '*' replace by '/' then only one fruit is there for snake

        int emptyFound = 0;
        int index = 0;
        while(emptyFound < random) {
            index++;
            if(board.getTile(index % GameBoard.MAP_SIZE, index / GameBoard.MAP_SIZE).equals(TileType.EMPTY)) { // if '/' replaced by '*' then nothing displays on the board 
                emptyFound++;
            }
        }
        board.setTile(index % GameBoard.MAP_SIZE, index / GameBoard.MAP_SIZE, TileType.FRUIT); // it also show nothing when replacing '/' by '/' 
    }

    @Override
    public void keyPressed(KeyEvent e) {
        if((e.getKeyCode() == KeyEvent.VK_UP)||(e.getKeyCode() == KeyEvent.VK_W)) {
            snake.setDirection(Direction.UP);
        }
        if((e.getKeyCode() == KeyEvent.VK_DOWN)||(e.getKeyCode() == KeyEvent.VK_S)) {
            snake.setDirection(Direction.DOWN);
        }
        if((e.getKeyCode() == KeyEvent.VK_LEFT)||(e.getKeyCode() == KeyEvent.VK_A)) {
            snake.setDirection(Direction.LEFT);
        }
        if((e.getKeyCode() == KeyEvent.VK_RIGHT)||(e.getKeyCode() == KeyEvent.VK_D)) {
            snake.setDirection(Direction.RIGHT);
        }
        if(e.getKeyCode() == KeyEvent.VK_ENTER && gameOver) {
            resetGame();
        }
    }

         public static void main(String[] args)  {
        new PlayGame().setVisible(true);

        /**JFrame frame = new JFrame("SnakeGame");
        frame.setDefaultCloseOperation(JFrame.HIDE_ON_CLOSE);
        frame.setResizable(false);

        Canvas canvas = new Canvas();
        canvas.setBackground(Color.black);
        canvas.setPreferredSize(new Dimension(GameBoard.MAP_SIZE * GameBoard.TILE_SIZE, GameBoard.MAP_SIZE * GameBoard.TILE_SIZE));

        frame.getContentPane().add(canvas);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true); 

        new Engine(canvas).startGame();*/


             }        
}

PlayGame.java

package org.psnbtech;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;


import javax.swing.JFrame;


public class PlayGame extends javax.swing.JFrame  {



   public PlayGame() {

        initComponents();      
    }


    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        jButton2 = new javax.swing.JButton();
        jButton3 = new javax.swing.JButton();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/org/psnbtech/GUID-4ED364DF-2D44-40F5-9F05-31D451F15EF1-low.png"))); // NOI18N
        jButton2.setText("Rules");
        jButton2.setMaximumSize(new java.awt.Dimension(89, 39));
        jButton2.setMinimumSize(new java.awt.Dimension(89, 39));
        jButton2.setPreferredSize(new java.awt.Dimension(89, 41));
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jButton3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/org/psnbtech/exit (1).png"))); // NOI18N
        jButton3.setText("Exit");
        jButton3.setPreferredSize(new java.awt.Dimension(89, 41));
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton3ActionPerformed(evt);
            }
        });

        jButton1.setIcon(new javax.swing.ImageIcon(getClass().getResource("/org/psnbtech/play.png"))); // NOI18N
        jButton1.setText("Play");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addContainerGap(277, Short.MAX_VALUE)
                .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(jPanel1Layout.createSequentialGroup()
                        .addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, 111, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addContainerGap())
                    .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                        .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, 109, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jButton1, javax.swing.GroupLayout.PREFERRED_SIZE, 109, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGap(27, 27, 27))))
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addGap(40, 40, 40)
                .addComponent(jButton1)
                .addGap(35, 35, 35)
                .addComponent(jButton2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(27, 27, 27)
                .addComponent(jButton3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(75, Short.MAX_VALUE))
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );

        pack();
    }// </editor-fold>                        

    private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        System.exit(0);        
    }                                        

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         

        this.dispose();
        new Rules().setVisible(true);

    }                                        



    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         

                JFrame frame = new JFrame("SnakeGame");
        frame.setVisible(true); 
                frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.setResizable(true);
        Canvas canvas = new Canvas();
        canvas.setBackground(Color.black);
                canvas.setPreferredSize(new Dimension(GameBoard.MAP_SIZE * GameBoard.TILE_SIZE, GameBoard.MAP_SIZE * GameBoard.TILE_SIZE));
                //canvas.addKeyListener((KeyListener) this);
                frame.getContentPane().add(canvas); 
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
                new Engine(canvas).startGame();
    }                                        


    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JButton jButton3;
    private javax.swing.JPanel jPanel1;
    // End of variables declaration                   
}

Answer 1

事情发生是因为你打电话

new PlayGame().setVisible(true);

和

frame.setVisible(true); 

仅显示第一帧，然后单击第二帧。

推荐的方法是始终只使用一帧，但使用多个面板 1. 渲染游戏的位置和 2. 选项窗格。交换它们，例如通过使用CardLayout。

也不要使用Canvas 使用JPanel 而不是覆盖paintComponent() 方法。

Answer 2

试试下面的：

JFrameAdd ja = new JFrameAdd();
ja.setVisible(true);
ja.setLocationRelativeTo(null);

希望对您有所帮助！