我想使用 Java Frame 创建一个毛毛虫游戏。它基本上有两个玩家试图占据一个方格来增加他们的分数。我一直在使用两个类:
毛毛虫类
package caterpillar;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;
class Caterpillar {
private Color color;
private Point position;
private char direction;
private Queue<Point> body;
private Queue<Character> commands;
private int score;
public Caterpillar (Color c, Point p){
color = c;
direction = 'E';
body = new LinkedList<Point>();
score = 0;
commands = new LinkedList<Character>();
for (int i = 0; i < 10; i++){
position= new Point(p.x + i, p.y);
body.offer(position);
}
}
public void setDirection(char direction){
commands.offer(new Character(direction));
}
public void move(CaterpillarGame game){
if(commands.size()>0){
Character c = (Character)commands.peek();
commands.poll();
direction = c.charValue();
if(direction == 'Z')
return;
}
Point np = newPosition();
if(game.canMove(np)){
body.poll();
body.offer(np);
position = np;
}
score+=game.squareScore(np);
}
private Point newPosition(){
int x = position.x;
int y = position.y;
if(direction == 'E')
x++;
else if(direction == 'W')
x--;
else if(direction == 'N')
y--;
else if(direction == 'S')
y++;
return new Point(x, y);
}
public boolean inPosition(Point np){ //check if position has alredy been occupied
Iterator <Point>it = body.iterator();
while(it.hasNext()){
Point location = it.next();
if(np.equals(location))
return true;
}
return false;
}
public int getScore(){
return score;
}
public void paint(Graphics g){
g.setColor(color);
Iterator <Point>it = body.iterator();
while(it.hasNext()){
Point p = it.next();
g.fillOval(5 + CaterpillarGame.SegmentSize * p.x,
15 + CaterpillarGame.SegmentSize * p.y,
CaterpillarGame.SegmentSize,
CaterpillarGame.SegmentSize);
}
}
}
游戏类别:
package caterpillar;
import java.awt.Color;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.Random;
import javax.swing.JLabel;
public class CaterpillarGame extends Frame{
final static int BoardWidth = 60;
final static int BoardHeight = 40;
final static int SegmentSize = 10;
private Caterpillar playerOne;
private Caterpillar playerTwo;
private Point square;
private int number; //points the players will get if occupy the square
private Random generator;
private JLabel score1, score2;// scores of two players
public static void main(String[] args){
CaterpillarGame game= new CaterpillarGame();
game.run();
}
public CaterpillarGame(){
setBackground(Color.GREEN);
setVisible(true);
setSize((BoardWidth+1)*SegmentSize, BoardHeight*SegmentSize + 30);
addKeyListener(new KeyReader());
playerOne = new Caterpillar(Color.blue, new Point(20, 10));
playerTwo = new Caterpillar(Color.red, new Point(20, 30));
addWindowListener(new CloseQuit());
generator = new Random();
number = 1;
score1 = new JLabel("Player One: "+playerOne.getScore());
score2 = new JLabel("Player Two: "+playerTwo.getScore());
this.add(score1);
this.add(score2);
square = new Point(newSquare());
}
public void run(){
while(true){
movePieces();
repaint();
try{
Thread.sleep(100);
}catch(Exception e){}
}
}
public void paint(Graphics g){
playerOne.paint(g);
playerTwo.paint(g);
g.setColor(Color.white);
g.fillRect(square.x, square.y, 10,10); //line 62, exception thrown
g.setColor(Color.BLACK);
g.drawString(Integer.toString(number), 10, 10);
}
public void movePieces(){
playerOne.move(this);
playerTwo.move(this);
}
public boolean canMove(Point np){
int x = np.x;
int y = np.y;
if((x<=0)||(y<=0))
return false;
if((x>=BoardWidth)||(y>=BoardHeight))
return false;
if(playerOne.inPosition(np))
return false;
if(playerTwo.inPosition(np))
return false;
return true;
}
private class KeyReader extends KeyAdapter{
public void keyPressed(KeyEvent e){
char c = e.getKeyChar();
switch(c){
case 'q': playerOne.setDirection('Z');
break;
case 'a': playerOne.setDirection('W');
break;
case 'd': playerOne.setDirection('E');
break;
case 'w': playerOne.setDirection('N');
break;
case 's': playerOne.setDirection('S');
break;
case 'p': playerTwo.setDirection('Z');
break;
case 'j': playerTwo.setDirection('W');
break;
case 'l': playerTwo.setDirection('E');
break;
case 'i': playerTwo.setDirection('N');
break;
case 'k': playerTwo.setDirection('S');
break;
}
}
}
public Point newSquare(){
Point p = new Point(generator.nextInt(51), generator.nextInt(31));
while(playerOne.inPosition(p)||playerTwo.inPosition(p)){
p = new Point(generator.nextInt(51), generator.nextInt(31));
}
number++;
return square = p;
}
public int squareScore(Point p){
if(p.equals(square)){
newSquare();
return number;
}
return 0;
}
private class CloseQuit extends WindowAdapter{
public void windowClosing(WindowEvent e){
System.exit(0);
}
}
}
这是我到目前为止所拥有的，但是当我运行该程序时遇到了几个问题:
- JLabels、方 block 和字符串未显示
- 它一直抛出 java.lang.NullPointerException
- 当一名玩家的分数达到一定数量时，如何停止程序？
- 如何检查毛毛虫是否接触到了正方形？
提前致谢。
最佳答案
the JLabels, square, and string didn't show up
他们是的，你只是把油漆过程搞砸了，以至于你阻止了他们被油漆。另外，我“相信”java.awt.Frame 使用 BorderLayout。
这是我们通常不鼓励人们重写paint的原因之一，打破绘画链非常容易
在执行任何自定义绘画之前添加对 super.paint 的调用。
@Override
public void paint(Graphics g) {
super.paint(g);
我更希望您使用基于 JComponent 的类中的 paintComponent 并将该对象添加到您的框架中，但这样做似乎受到限制...
此外，将布局管理器更改为 FlowLayout 之类的内容，以使两个标签都显示在屏幕上。
参见Painting in AWT and Swing和 Laying Out Components Within a Container了解更多详情
it kept throwing java.lang.NullPointerException
这似乎是一个竞争条件。本质上，您在完成 UI 要求的初始化之前就在框架上调用 setVisible，这会导致在框架完全初始化之前调用 paint。
最后调用setVisible。更好的是，不要从构造函数中调用 setVisible...
how do i have the program stopped when the score of one player reaches a certain number?
...在您的“游戏循环”中，您需要检查分数的状态，并在满足所需状态时打破“游戏循环”...
how to check if a caterpillar touches the square?
这是一个更复杂的问题。本质上，您可以使用 Rectangle (或其他 Shape 对象)的 interests 或 contains 方法。您知道正方形 的点 和毛毛虫 的“线段”在哪里。您知道正方形和“线段”的大小。
您需要比较每个线段，看看它们是否与正方形相交。仔细看看java.awt.Rectangle了解更多详情
关于java - 在框架上绘图和 JLabel，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/29067228/