小编nom*_*986的帖子

我正在尝试编写一个Java应用程序,它在屏幕上绘制多个球,从框架的边缘反弹.我可以成功地画出一个球.但是当我添加第二个球时,它会覆盖我绘制的初始球.代码是:

import java.awt.*;
import javax.swing.*;
import java.util.ArrayList;
import java.util.List;

public class Ball extends JPanel implements Runnable {

    List<Ball> balls = new ArrayList<Ball>();   
Color color;
int diameter;
long delay;
private int x;
private int y;
private int vx;
private int vy;

public Ball(String ballcolor, int xvelocity, int yvelocity) {
    if(ballcolor == "red") {
        color = Color.red;
    }
    else if(ballcolor == "blue") {
        color = Color.blue;
    }
    else if(ballcolor == "black") {
        color = Color.black;
    }
    else if(ballcolor == "cyan") {
        color …

我已经编写了代码来驱动差分驱动机器人通过我选择的固定路径.我试图从命令行运行代码:java StartRobot或能够在浏览器中运行应用程序和Applet.我的代码如下:

import java.awt.*;
import javax.swing.*;
import java.util.ArrayList;
import java.util.List;

class DifferentialDriveRobot {

public static void main(String[] args) {
    new DifferentialDriveRobot();
}

public DifferentialDriveRobot() {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
            createAndShowGUI();
        }
    });
}

public void createAndShowGUI() {
    JFrame frame = new JFrame("Differential Drive Robot");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new BorderLayout());
    Robots robots = new Robots();
    frame.add(robots);
    frame.setSize(400,400);
    frame.setVisible(true);

    new Thread(new Drive(robots)).start();
}

public static int random(int maxRange) {
    return (int) Math.round((Math.random() * maxRange));
}

public class Robots extends JPanel …