我在雨模拟器上工作。我的想法是每一滴都应该是一个对象，但由于某种原因它们不会出现在JFrame上。如果我改变它们出现的矩形的坐标值，但是如果我随机化数字则不会。是什么导致物体不出现？
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Rain extends RainDrop implements ActionListener{
//Change the following 2 lines of variables to change the graphics
static int width = 1000, height = 600;
int dropAmount = 650, speed = 10;
Timer tm = new Timer(speed, this);
RainDrop[] RainDrop = new RainDrop[650];
public Rain(){
for(int i = 0; RainDrop.length > i; i++){
RainDrop[i] = new RainDrop();
RainDrop[i].generateRain();
add(RainDrop[i]);
}
repaint();
}
public void paintComponent(Graphics g){
tm.start();
}
public void actionPerformed(ActionEvent e){
repaint();
}
public static void main(String[] args) {
JFrame f = new JFrame();
f.setLocation(100, 100);
f.setSize(width, height);
f.setTitle("Rain");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Rain Rain = new Rain();
f.add(Rain);
f.setResizable(true);
f.setVisible(true);
}
}
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class RainDrop extends JPanel{
//Drop [0] is used to store x values
//Drop [1] is used to store y values
//Drop [2] is used to store height values
//Drop [3] is used to store width values
//Drop [4] is used to store velocity values
private int[] Drop = new int [5];
private int width = 1000, height = 600;
public RainDrop(){
}
public int[] generateRain(){
Drop [0] = (int) (Math.random() * width);
Drop [1] = (int) (Math.random() * height);
Drop [2] = (int) (Math.random() * 13);
Drop [3] = (int) (Math.random() * 4);
Drop [4] = (int) (Math.random() * 6);
if(Drop [2] < 5) Drop [2] += 9;
if(Drop [3] < 3) Drop [3] += 3;
if(Drop [3] == 5) Drop [3] = 4;
if(Drop [4] < 3) Drop [4] += 3;
return Drop;
}
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.red);
g.fillRect(Drop [0], Drop [1], 5, 20);
}
}
答案 0 :(得分：2)
基本设计错了。 Rain不应延长RainDrop。
Rain应该只是一个带有paintComponent()方法的JPanel，它绘制一个RainDrop对象。
创建ArrayList以保留RainDrop个对象。然后，您可以在Rain面板中启动计时器。当Timer触发时，您可以遍历ArrayList中的所有RainDrop个对象并更改每个RainDrop的位置，然后重新绘制（）面板。
以下是显示此基本方法的示例。它展示了如何在面板周围移动球：
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
import javax.swing.*;
import javax.swing.Timer;
public class BallAnimation4
{
private static void createAndShowUI()
{
BallPanel panel = new BallPanel();
JFrame frame = new JFrame("BallAnimation4");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add( panel );
frame.setSize(800, 600);
frame.setLocationRelativeTo( null );
//frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible( true );
panel.addBalls(5);
panel.startAnimation();
}
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable()
{
public void run()
{
createAndShowUI();
}
});
}
}
class BallPanel extends JPanel implements ActionListener
{
private ArrayList<Ball> balls = new ArrayList<Ball>();
public BallPanel()
{
setLayout( null );
setBackground( Color.BLACK );
}
public void addBalls(int ballCount)
{
Random random = new Random();
for (int i = 0; i < ballCount; i++)
{
Ball ball = new Ball();
ball.setRandomColor(true);
ball.setLocation(random.nextInt(getWidth()), random.nextInt(getHeight()));
ball.setMoveRate(32, 32, 1, 1, true);
// ball.setMoveRate(16, 16, 1, 1, true);
ball.setSize(32, 32);
balls.add( ball );
}
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
for (Ball ball: balls)
{
ball.draw(g);
}
}
public void startAnimation()
{
Timer timer = new Timer(75, this);
timer.start();
}
public void actionPerformed(ActionEvent e)
{
move();
repaint();
}
private void move()
{
for (Ball ball : balls)
{
ball.move(this);
}
}
class Ball
{
public Color color = Color.BLACK;
public int x = 0;
public int y = 0;
public int width = 1;
public int height = 1;
private int moveX = 1;
private int moveY = 1;
private int directionX = 1;
private int directionY = 1;
private int xScale = moveX;
private int yScale = moveY;
private boolean randomMove = false;
private boolean randomColor = false;
private Random myRand = null;
public Ball()
{
myRand = new Random();
setRandomColor(randomColor);
}
public void move(JPanel parent)
{
int iRight = parent.getSize().width;
int iBottom = parent.getSize().height;
x += 5 + (xScale * directionX);
y += 5 + (yScale * directionY);
if (x <= 0)
{
x = 0;
directionX *= (-1);
xScale = randomMove ? myRand.nextInt(moveX) : moveX;
if (randomColor) setRandomColor(randomColor);
}
if (x >= iRight - width)
{
x = iRight - width;
directionX *= (-1);
xScale = randomMove ? myRand.nextInt(moveX) : moveX;
if (randomColor) setRandomColor(randomColor);
}
if (y <= 0)
{
y = 0;
directionY *= (-1);
yScale = randomMove ? myRand.nextInt(moveY) : moveY;
if (randomColor) setRandomColor(randomColor);
}
if (y >= iBottom - height)
{
y = iBottom - height;
directionY *= (-1);
yScale = randomMove ? myRand.nextInt(moveY) : moveY;
if (randomColor) setRandomColor(randomColor);
}
}
public void draw(Graphics g)
{
g.setColor(color);
g.fillOval(x, y, width, height);
}
public void setColor(Color c)
{
color = c;
}
public void setLocation(int x, int y)
{
this.x = x;
this.y = y;
}
public void setMoveRate(int xMove, int yMove, int xDir, int yDir, boolean randMove)
{
this.moveX = xMove;
this.moveY = yMove;
directionX = xDir;
directionY = yDir;
randomMove = randMove;
}
public void setRandomColor(boolean randomColor)
{
this.randomColor = randomColor;
switch (myRand.nextInt(3))
{
case 0: color = Color.BLUE;
break;
case 1: color = Color.GREEN;
break;
case 2: color = Color.RED;
break;
default: color = Color.BLACK;
break;
}
}
public void setSize(int width, int height)
{
this.width = width;
this.height = height;
}
}
}
答案 1 :(得分：0)
如果我把randoms拿出来，我无法让你的代码显示任何东西，但我确实看到你实际上并没有画出雨滴。
在Rain.java中：
public void paintComponent(Graphics g) {
for (int i = 0; RainDrop.length > i; i++) {
RainDrop[i].generateRain();
RainDrop[i].paintComponent(g);
}
}
并将tm.start();放入构造函数中。每次重新绘制时都不需要启动计时器