我正在嘗試用 Java 構建彈跳游戲。我的專案有三個類，即Main創建一個新視窗（框架）的類，其中繪制了游戲按鈕和反彈物件。GameInterface代表正在繪制的框架的屬性的類RightPanel和我創建的類，以便我可以覆寫paint(Graphics)繪制反彈物件的方法。到目前為止，這是我設法用代碼繪制的。
您可以看到我有兩個 JPanel，一個持有我的按鈕，另一個接受在其上繪制圓球，即RightPanel
我需要按鈕事件偵聽器的幫助來上下移動球以及當用戶按住按鈕時向下，它需要繼續向下移動，直到到達向下順序，sam 為向上按鈕。下面提供了正在使用的代碼。
游戲介面類
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
public class GameInterface extends JFrame {
//we need this panel declaration in the class level for reference from other methods
RightPanel rightpanel;
//define the physical properties of the window
public GameInterface(){
setSize(new Dimension(600, 600));
setResizable(false);
setTitle("Bounce Game");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBackground(Color.black);
//define a new JSplitPane and use it to add two JPanels
JPanel leftpanel= new JPanel();
//add buttons to the left panel programatically
JButton up= new JButton("Move up");
//set the event listeners for the buttons
up.addActionListener(new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
//move my ball up
//clear and redraw the ball while in a new position, use a timer or
something
}
});
JButton down = new JButton("Move down");
down.addActionListener(new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
//move my ball down
// rightpanel.getGraphics.fillColor(Color.RED);
}
});
leftpanel.add(up);
leftpanel.add(down);
//add a new RightPanel with a drawn red object
rightpanel= new RightPanel();
JSplitPane splitpane= new JSplitPane(JSplitPane.HORIZONTAL_SPLIT,leftpanel,rightpanel);
this.add(splitpane);
setVisible(true);
}
}
右面板類
import javax.swing.*;
import java.awt.*;
public class RightPanel extends JPanel {
//define the position where the circle will be drawn
private int positionX=150;
private int positionY=150;
//I had an idea where we need a timer and then on delay we
//decrement positionX by 3 for move down but can't figure out how to clear RightPanel
private int radius=100;//as the shape is a circle
//override the paint method to draw the bounce ball on the second panel
@Override
public void paint(Graphics g) {
g.setColor(Color.RED);
g.fillOval(positionX,positionY,radius,radius);
}
}
主班
public class Main
{
public static void main(String args[]){
new GameInterface();
}
}
如何在我的代碼中添加邏輯以使其向上和向下移動圓圈，謝謝。我嘗試使用計時器物件清除面板，然后在球的新位置重新繪制球，但它繪制了一個垂直條，而不是清除原來繪制的球。
uj5u.com熱心網友回復：
- 永遠不要在組件上呼叫 getGraphics()。
- 覆寫paintComponent不繪制
- 在覆寫中呼叫 super.paintComponent(g)。
- 提供 RightPanel 類設定器方法，允許您更改繪圖的 positionX 和 positionY 位置，
- 在按鈕偵聽器中，呼叫適當的 setter 方法，然后在更改位置后在 RightPanel 實體上呼叫 repaint()。
例如：
下面的關鍵代碼在 ActionListener 中，您可以在其中更新位置值并呼叫重繪：
moveRightBtn.addActionListener(e -> {
// get and update the x position
int x = drawOval.getPositionX();
x = DELTA;
// call the setter method
drawOval.setPositionX(x);
// request that Java repaint the JPanel
drawOval.repaint();
});
并在繪圖 JPanel 的 paintComponent 方法中呼叫 super 的方法并繪制橢圓：
@Override
protected void paintComponent(Graphics g) {
// this is needed to do house-keeping painting, to clear "dirty" pixels
super.paintComponent(g);
// this is needed to draw smooth graphics
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(OVAL_COLOR);
g2.fillOval(positionX, positionY, RADIUS, RADIUS);
}
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.*;
@SuppressWarnings("serial")
public class MoveCircle extends JPanel {
private static final int DELTA = 5;
private DrawOval drawOval = new DrawOval();
public MoveCircle() {
JButton moveRightBtn = new JButton("Move Right");
moveRightBtn.addActionListener(e -> {
// get and update the x position
int x = drawOval.getPositionX();
x = DELTA;
// call the setter method
drawOval.setPositionX(x);
// request that Java repaint the JPanel
drawOval.repaint();
});
JPanel buttonPanel = new JPanel();
buttonPanel.add(moveRightBtn);
setLayout(new BorderLayout());
add(drawOval);
add(buttonPanel, BorderLayout.LINE_START);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
MoveCircle mainPanel = new MoveCircle();
JFrame frame = new JFrame("GUI");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
});
}
}
@SuppressWarnings("serial")
class DrawOval extends JPanel {
private static final int RADIUS = 100;
private static final int PANEL_WIDTH = 600;
private static final int PANEL_HEIGHT = 450;
private static final Color OVAL_COLOR = Color.RED;
private int positionX = 0;
private int positionY = 0;
public DrawOval() {
setPreferredSize(new Dimension(PANEL_WIDTH, PANEL_HEIGHT));
}
public int getPositionX() {
return positionX;
}
public void setPositionX(int positionX) {
this.positionX = positionX;
}
public int getPositionY() {
return positionY;
}
public void setPositionY(int positionY) {
this.positionY = positionY;
}
@Override
protected void paintComponent(Graphics g) {
// this is needed to do house-keeping painting, to clear "dirty" pixels
super.paintComponent(g);
// this is needed to draw smooth graphics
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(OVAL_COLOR);
g2.fillOval(positionX, positionY, RADIUS, RADIUS);
}
}
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