java-AWT fillOval不繪制新對象

Question

我正在嘗試通過在面板上添加第二個球來修改網站上舊式乒乓球游戲的示例代碼。 到目前為止，我正在復制生成第一個球的步驟。 但是，我以某種方式失敗了。 盡管該程序是可執行的，但我添加的第二個球沒有出現。 我不知道問題出在哪里。 球方法在PanelPelota類下。 到目前為止，我只是復制變量和一些函數。 這是代碼：

主班

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

public class Main extends JFrame {

private static final long serialVersionUID = 1L; // Eclipse added this automatically

private JPanel jContentPane = null;

private PanelPelota panel = null; // This is the panel of the game class

private PanelPelota getPanel() {
    if (panel == null) {
        panel = new PanelPelota(); // The panel is created
    }
    return panel;
}

/**
 * This is the default constructor
 */
public Main() {
    super();
    initialize();
    // Listeners for the keyboard
    this.addKeyListener(new KeyAdapter() {
        // Method for the key pressed
        public void keyPressed(KeyEvent evt) {
            formKeyPressed(evt);
        }

        // Method for the key released
        public void keyReleased(KeyEvent evt) {
            formKeyReleased(evt);
        }
    });

}

// Here i'm stating the method that will send the key pressed to the game class
private void formKeyPressed(KeyEvent evt) {
    panel.keyPressed(evt);
}

// Here i'm stating the method that will send the key released to the game class
private void formKeyReleased(KeyEvent evt) {
    panel.keyReleased(evt);
}

/**
 * This method initializes this
 *
 * @return void
 */
private void initialize() {
    this.setResizable(false);
    this.setBounds(new Rectangle(312, 184, 250, 250)); // Position on the desktop
    this.setMinimumSize(new Dimension(250, 250));
    this.setMaximumSize(new Dimension(250, 250));
    this.setContentPane(getJContentPane());
    this.setTitle("Pong");
}

/**
 * This method initializes jContentPane
 *
 * @return javax.swing.JPanel
 */
private JPanel getJContentPane() {
    if (jContentPane == null) {
        jContentPane = new JPanel();
        jContentPane.setLayout(new BorderLayout());
        jContentPane.add(getPanel(), BorderLayout.CENTER);
    }
    return jContentPane;
}

public static void main(String[] args) {
    // TODO Auto-generated method stub
    SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            Main thisClass = new Main();
            thisClass.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            thisClass.setVisible(true);
        }
    });
}
}

PanelPelota類

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

public class PanelPelota extends JPanel implements Runnable {

private static final long serialVersionUID = 1L;
// Positions on X and Y for the ball, player 1 and player 2
private int pelotaX = 10, pelotaY = 100, pelota2X = 230, pelota2Y = 100, jug1X = 10, jug1Y = 100, jug2X = 230, jug2Y = 100;
Thread hilo;
int derecha = 5;// to the right
int izquierda = -5; // to the left
int arriba = 5; // upward
int abajo = -5; // down
int ancho, alto; // Width and height of the ball
int ancho2, alto2;
// Scores
int contPlay1 = 0, contPlay2 = 0;
boolean player1FlagArr, player1FlagAba, player2FlagArr, player2FlagAba;
boolean juego, gameOver;

public PanelPelota() {
    juego = true;
    hilo = new Thread(this);
    hilo.start();
}

// Draw ball and ships
public void paintComponent(Graphics gc) {
    setOpaque(false);
    super.paintComponent(gc);

    // Draw ball
    gc.setColor(Color.black);
    gc.fillOval(pelotaX, pelotaY, 8, 8);
    gc.fillOval(pelota2X, pelota2Y, 8, 8);

    // Draw ships
    gc.fillRect(jug1X, jug1Y, 10, 25);
    gc.fillRect(jug2X, jug2Y, 10, 25);

    // Draw scores
    gc.drawString("Jugador1: " + contPlay1, 25, 10);
    gc.drawString("Jugador2: " + contPlay2, 150, 10);

    if (gameOver) {
        //gc.drawString("Game Over", 100, 125);
        Restart replay = new Restart();
        JPanel midPanel = new JPanel();
        replay.setVisible(true);
        if(contPlay1 == 6)
            midPanel.add(new JLabel("Player1 wins!"));
        if(contPlay2 == 6)
            midPanel.add(new JLabel("Player2 wins!"));
        replay.setTitle("Game Over!");
        replay.setSize(300, 100);
        replay.setLocationRelativeTo(null);

        midPanel.add(new JLabel(""));
        replay.add(midPanel, BorderLayout.CENTER);
        replay.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

// Positions on X and Y for the ball
public void dibujarPelota(int nx, int ny) {
    pelotaX = nx;
    pelotaY = ny;
    this.ancho = this.getWidth();
    this.alto = this.getHeight();
    repaint();
}

public void dibujarPelota2(int nx, int ny) {
    pelotaX = nx;
    pelotaY = ny;
    this.ancho2 = this.getWidth();
    this.alto2 = this.getHeight();
    repaint();
}

// Here we receive from the game container class the key pressed
public void keyPressed(KeyEvent evt) {
    switch (evt.getKeyCode()) {
    // Move ship 1
    case KeyEvent.VK_W:
        player1FlagArr = true;
        break;
    case KeyEvent.VK_S:
        player1FlagAba = true;
        break;

    // Move ship 2
    case KeyEvent.VK_UP:
        player2FlagArr = true;
        break;
    case KeyEvent.VK_DOWN:
        player2FlagAba = true;
        break;
    }
}

// Here we receive from the game container class the key released
public void keyReleased(KeyEvent evt) {
    switch (evt.getKeyCode()) {
    // Mover Nave1
    case KeyEvent.VK_W:
        player1FlagArr = false;
        break;
    case KeyEvent.VK_S:
        player1FlagAba = false;
        break;

    // Mover nave 2
    case KeyEvent.VK_UP:
        player2FlagArr = false;
        break;
    case KeyEvent.VK_DOWN:
        player2FlagAba = false;
        break;
    }
}

// Move player 1
public void moverPlayer1() {
    if (player1FlagArr == true && jug1Y >= 0)
        jug1Y += abajo;
    if (player1FlagAba == true && jug1Y <= (this.getHeight() - 25))
        jug1Y += arriba;
    dibujarPlayer1(jug1X, jug1Y);
}

// Move player 2
public void moverPlayer2() {
    if (player2FlagArr == true && jug2Y >= 0)
        jug2Y += abajo;
    if (player2FlagAba == true && jug2Y <= (this.getHeight() - 25))
        jug2Y += arriba;
    dibujarPlayer2(jug2X, jug2Y);
}

// Position on Y for the player 1
public void dibujarPlayer1(int x, int y) {
    this.jug1X = x;
    this.jug1Y = y;
    repaint();
}

// Position on Y for the player 2
public void dibujarPlayer2(int x, int y) {
    this.jug2X = x;
    this.jug2Y = y;
    repaint();
}

public void run() {
    // TODO Auto-generated method stub
    boolean izqDer = false;
    boolean arrAba = false;
    boolean izqDer2 = false;
    boolean arrAba2 = false;

    while (true) {

        if (juego) {

            // The ball move from left to right
            if (izqDer) {
                // a la derecha
                pelotaX += derecha;
                if (pelotaX >= (ancho - 8))
                    izqDer = false;
            } else {
                // a la izquierda
                pelotaX += izquierda;
                if (pelotaX <= 0)
                    izqDer = true;
            }

            // The ball moves from up to down
            if (arrAba) {
                // hacia arriba
                pelotaY += arriba;
                if (pelotaY >= (alto - 8))
                    arrAba = false;

            } else {
                // hacia abajo
                pelotaY += abajo;
                if (pelotaY <= 0)
                    arrAba = true;
            }
            dibujarPelota(pelotaX, pelotaY);

            // The second ball move from left to right
            if (izqDer2) {
                // a la derecha
                pelota2X += derecha;
                if (pelota2X >= (ancho - 8))
                    izqDer2 = false;
            } else {
                // a la izquierda
                pelota2X += izquierda;
                if (pelota2X <= 0)
                    izqDer2 = true;
            }

            // The ball moves from up to down
            if (arrAba2) {
                // hacia arriba
                pelota2Y += arriba;
                if (pelota2Y >= (alto - 8))
                    arrAba2 = false;

            } else {
                // hacia abajo
                pelota2Y += abajo;
                if (pelota2Y <= 0)
                    arrAba2 = true;
            }
            dibujarPelota2(pelota2X, pelota2Y);

            // Delay
            try {
                Thread.sleep(50);
            } catch (InterruptedException ex) {

            }

            // Move player 1
            moverPlayer1();

            // Move player 2
            moverPlayer2();

            // The score of the player 1 increase
            if (pelotaX >= (ancho - 8))
                contPlay1++;

            // The score of the player 2 increase
            if (pelotaX == 0)
                contPlay2++;

            // Game over. Here you can change 6 to any value
            // When the score reach to the value, the game will end
            if (contPlay1 == 6 || contPlay2 == 6) {
                juego = false;
                gameOver = true;
            }

            // The ball stroke with the player 1
            if (pelotaX == jug1X + 10 && pelotaY >= jug1Y && pelotaY <= (jug1Y + 25))
                izqDer = true;

            // The ball stroke with the player 2
            if (pelotaX == (jug2X - 5) && pelotaY >= jug2Y && pelotaY <= (jug2Y + 25))
                izqDer = false;

            // The ball2 stroke with the player 1
            if (pelota2X == jug1X + 10 && pelota2Y >= jug1Y && pelota2Y <= (jug1Y + 25))
                izqDer2 = true;

            // The ball2 stroke with the player 2
            if (pelota2X == (jug2X - 5) && pelota2Y >= jug2Y && pelota2Y <= (jug2Y + 25))
                izqDer2 = false;
        }
    }
}
}

重新啟動課程（由我創建）

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

public class Restart extends JFrame{
private static final long serialVersionUID = 1L;

public JButton restart = new JButton("Restart");

public Restart() {
    Container cp = getContentPane(); 
    cp.setLayout(new BorderLayout());

    JPanel bottomPanel = new JPanel();
    bottomPanel.add(restart);
    cp.add(bottomPanel, BorderLayout.SOUTH);

    restart.addActionListener(new ActionListener() {

          public void actionPerformed(ActionEvent e) {
            //Creating the window with all its awesome snaky features
            Main thisClass= new Main();
            thisClass.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            thisClass.setVisible(true);

            //Close Menu once select
            String cmd = e.getActionCommand();
            if(cmd.equals("Restart"))
            {
                dispose();
            }
          };
      });
}
}

如果有問題，我正在使用Eclipse IDE。

先感謝您。

Answer 1

dibujarPelota和dibujarPelota2將值分配給相同的實例字段，有效覆蓋它們。

public void dibujarPelota(int nx, int ny) {
    pelotaX = nx;
    pelotaY = ny;
    this.ancho = this.getWidth();
    this.alto = this.getHeight();
    repaint();
}

public void dibujarPelota2(int nx, int ny) {
    pelotaX = nx;
    pelotaY = ny;
    this.ancho2 = this.getWidth();
    this.alto2 = this.getHeight();
    repaint();
}

因此，是的，您的第二個球已更新並繪制，但與第一個球位於同一位置。

更改dibujarPelota2將nx分配給pelota2X ，將ny分配給pelota2Y

public void dibujarPelota2(int nx, int ny) {
    pelota2X = nx;
    pelota2Y = ny;
    this.ancho2 = this.getWidth();
    this.alto2 = this.getHeight();
    repaint();
}

另外，請注意，您使用的示例並不是最佳示例，因為它正在更新UI依賴於EDT上下文之外的狀態信息，盡管這可能只是一個小問題，但它可以迅速升級