void mousePressed(){ onPressed = true; if (showInstruction){ background(0); showInstruction = false;} } void mouseReleased(){ onPressed = false; } void keyPressed(){ if (key =='c'){ for (int i=pts.size()-1; i>-1; i--){ Particle p = pts.get(i); pts.remove(i) ;} background(0);}} class Particle{ PVector loc,vel,acc; int lifeSpan,passedLife; boolean dead; float alpha,weight,weightRange,decay,xoffset,yoffset; color c; Particle(float x,float y,float xoffset,float yoffset){ loc=new PVector(x,y); float randDegrees=random(360); vel=new PVector(cos(radians(randDegrees)),sin(radians(randDegrees))); vel.mult(random(5)); acc=new PVector(0,0); lifeSpan = int(random(30,90)); decay = random(0.75,0.9); c = color(random(255),random(255),255); weightRange = random(3,50); this.xoffset=xoffset; this.yoffset=yoffset; } void update(){ if(passedLife>=lifeSpan){ dead = true; }else{ passedLife++;} alpha=float(lifeSpan-passedLife)/lifeSpan*70+50; weight=float(lifeSpan-passedLife)/lifeSpan*weightRange; acc.set(0,0); float rn=(noise((loc.x+frameCount+xoffset)*0.01,(loc.y+frameCount+yoffset)*0.01)-0.5)*4*PI; float mag=noise((loc.y+frameCount)*0.01,(loc.x+frameCount)*0.01); PVector dir=new PVector()cos(rn),sin(rn)); acc.add(dir); acc.mult(mag); float randDegrees=random(360); PVector randV=new PVector(cos(radians(randDegrees)),sin(radians(randDegrees))); randV.mult(0.5); acc.add(randV); vel.add(acc); vel.mult(decay); vel.limit(3); loc.add(vel);} void display(){ strokeWeight(weight+1.5); stroke(0,alpha); point(loc.x,loc.y); strokeWeight(weight); stoke(c); point(loc.x,loc.y); }为什么错了
时间: 2024-03-19 22:40:03 浏览: 122
这段代码中存在几处错误,我来帮你逐一解释:
1. `lifeSpan,passedLife` 这行代码中,逗号应该被替换为分号。
2. `xoffset` 和 `yoffset` 在 `Particle` 类的构造函数中并没有被正确地声明为成员变量。应该将它们声明为 `this.xoffset` 和 `this.yoffset`。
3. 在 `Particle` 类的 `display()` 函数中,`stoke()` 应该被替换为 `stroke()`。
除了上述的错误之外,整个代码片段中缺少了一些必要的声明和变量初始化,例如 `ArrayList<Particle> pts` 和 `boolean onPressed` 等。你需要在代码的其他部分进行声明和初始化才能让它正确运行。
另外,为了更好地帮助你解决问题,我建议你提供更多的上下文信息和错误提示,这样我可以更准确地指出问题所在。
相关问题
import javax.swing.*; import java.awt.*; import java.awt.event.*; public class DrawingBoard extends JPanel implements MouseMotionListener, MouseListener { private int lastX, lastY; public DrawingBoard() { setPreferredSize(new Dimension(400, 400)); setBackground(Color.WHITE); addMouseMotionListener(this); addMouseListener(this); } public void paintComponent(Graphics g) { super.paintComponent(g); Font font = new Font("Arial", Font.BOLD, 20); g.setFont(font); g.setColor(Color.BLUE); g.drawString("Hello World!", 50, 50); } public void mouseDragged(MouseEvent e) { Graphics g = getGraphics(); g.drawLine(lastX, lastY, e.getX(), e.getY()); lastX = e.getX(); lastY = e.getY(); } public void mousePressed(MouseEvent e) { lastX = e.getX(); lastY = e.getY(); } public void mouseMoved(MouseEvent e) {} public void mouseClicked(MouseEvent e) {} public void mouseEntered(MouseEvent e) {} public void mouseExited(MouseEvent e) {} public void mouseReleased(MouseEvent e) {} public static void main(String[] args) { JFrame frame = new JFrame("Drawing Board"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(new DrawingBoard()); frame.pack(); frame.setVisible(true); } }加注释
下面是对这段 Java 代码的注释:
```java
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
// DrawingBoard 类继承了 JPanel 类并实现了 MouseMotionListener 和 MouseListener 接口
public class DrawingBoard extends JPanel implements MouseMotionListener, MouseListener {
private int lastX, lastY; // 上一次鼠标移动的位置
// 构造函数
public DrawingBoard() {
setPreferredSize(new Dimension(400, 400)); // 设置 DrawingBoard 的首选大小
setBackground(Color.WHITE); // 设置 DrawingBoard 的背景颜色为白色
addMouseMotionListener(this); // 添加鼠标移动事件监听器
addMouseListener(this); // 添加鼠标事件监听器
}
// 重写 JPanel 的 paintComponent 方法,在 DrawingBoard 上绘制字符串
public void paintComponent(Graphics g) {
super.paintComponent(g); // 先调用父类的 paintComponent 方法
Font font = new Font("Arial", Font.BOLD, 20); // 创建字体对象
g.setFont(font); // 设置字体
g.setColor(Color.BLUE); // 设置画笔颜色为蓝色
g.drawString("Hello World!", 50, 50); // 在 DrawingBoard 上绘制字符串
}
// 鼠标拖动事件监听器
public void mouseDragged(MouseEvent e) {
Graphics g = getGraphics(); // 获取 DrawingBoard 上的画笔对象
g.drawLine(lastX, lastY, e.getX(), e.getY()); // 绘制直线,连接上一次鼠标移动的位置和当前位置
lastX = e.getX(); // 更新上一次鼠标移动的位置
lastY = e.getY();
}
// 鼠标按下事件监听器
public void mousePressed(MouseEvent e) {
lastX = e.getX(); // 记录上一次鼠标移动的位置
lastY = e.getY();
}
// 鼠标移动事件监听器(不需要实现)
public void mouseMoved(MouseEvent e) {}
// 鼠标单击事件监听器(不需要实现)
public void mouseClicked(MouseEvent e) {}
// 鼠标进入 DrawingBoard 事件监听器(不需要实现)
public void mouseEntered(MouseEvent e) {}
// 鼠标离开 DrawingBoard 事件监听器(不需要实现)
public void mouseExited(MouseEvent e) {}
// 鼠标释放事件监听器(不需要实现)
public void mouseReleased(MouseEvent e) {}
// 主函数
public static void main(String[] args) {
JFrame frame = new JFrame("Drawing Board"); // 创建 JFrame 对象
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 设置关闭操作
frame.getContentPane().add(new DrawingBoard()); // 在 JFrame 上添加 DrawingBoard
frame.pack(); // 调整 JFrame 的大小以适应 DrawingBoard
frame.setVisible(true); // 显示 JFrame
}
}
```
protected void paintComponent(Graphics g) { super.paintComponent(g); if (test.getMapNodes() != null) { System.out.println("enter the drawGreenNodes"); TwoTuple[] nodes = test.getMapNodes(); g.setColor(Color.GREEN); for (int i = 0; i < nodes.length; i++) { if (nodes[i] != null) { int x = nodes[i].first; int y = nodes[i].second; g.fillRect(y * CELL_SIZE + CELL_SIZE + CELL_SIZE / 4, x * CELL_SIZE + CELL_SIZE + CELL_SIZE / 4, CELL_SIZE / 2, CELL_SIZE / 2); } } }就是点击xxx然后绿色出现,演示一下
要在Java Swing中实现点击出现标记的效果,您可以使用MouseListener接口来监听鼠标点击事件,并在适当的位置绘制标记。
以下是一个简单的示例代码,演示了如何在鼠标点击时在指定位置绘制一个绿色方块:
```java
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ClickToMark extends JPanel implements MouseListener {
private int mouseX, mouseY;
private boolean mouseClicked;
public ClickToMark() {
setPreferredSize(new Dimension(400, 400));
setBackground(Color.WHITE);
addMouseListener(this);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (mouseClicked) {
g.setColor(Color.GREEN);
g.fillRect(mouseX - 5, mouseY - 5, 10, 10);
}
}
public void mouseClicked(MouseEvent e) {
mouseX = e.getX();
mouseY = e.getY();
mouseClicked = true;
repaint();
}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public static void main(String[] args) {
JFrame frame = new JFrame("Click to Mark");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new ClickToMark());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
```
您可以将`mouseClicked`变量设置为true,以在鼠标点击时绘制标记。您可以根据需要调整绘制标记的位置和大小。
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