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java.lang.NullPointerException未知错误？？

渐渐鱼 发布于 2018-10-03 19:07， 2627 次点击
程序代码：
package application;
   
import java.util.LinkedList;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

import javafx.animation.KeyFrame;
import javafx.animation.KeyValue;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.event.EventHandler;
import javafx.stage.Stage;
import javafx.util.Duration;
import javafx.scene.Group;

import javafx.scene.Scene;

import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.Circle;



public class Main extends Application
{
    static String keyCode =null;
   
   
    @Override
    public void start(Stage stage)
    {

            Group g = new Group();
            
            Scene scene = new Scene(g,1024,700);
            
            LinkedList<Circle> list = new LinkedList<>();
            LinkedList<Circle> list1 = new LinkedList<>();
            
            //画食物
            Random r = new Random();
            
            for(int i=0;i<10;i++)
            {
                int x =r.nextInt(1009-15+1)+15;
                int y =r.nextInt(685-15+1)+15;
               
                Circle cir = new Circle();
                cir.setCenterX(x);
                cir.setCenterY(y);
                cir.setRadius(15);
                cir.setFill(Color.BLACK);
                list1.add(cir);
            }
           

            //画蛇   
            Arc arc = new Arc();
            arc.setFill(Color.BLACK);
            arc.setCenterX(300);
            arc.setCenterY(200);
            arc.setRadiusX(15);
            arc.setRadiusY(15);
            arc.setStartAngle(45);
            arc.setLength(270);
            arc.setType(ArcType.ROUND);
            
            for(int i=0;i<5;i++)
            {
                Circle cir = new Circle();
                cir.setCenterX(270-30*i);
                cir.setCenterY(200);
                cir.setRadius(15);
                cir.setFill(Color.BLACK);
                list.add(cir);
            }
            //定义移动
            class Move
            {

                    public void moveObj(DoubleProperty arcValue, double arcMove)
                    {
                        
                        Timeline timeline=new Timeline();
                        //head
                        KeyValue ARCValue = new KeyValue(arcValue,arcMove);
                        KeyFrame ARCkeyFrame = new KeyFrame(Duration.millis(500),ARCValue);
                        timeline.getKeyFrames().add(ARCkeyFrame);
                        
                        //body
                        double preX=arc.getCenterX();
                        double preY=arc.getCenterY();
                        boolean isFirst=true;
                        for(int i=0;i<list.size();i++)
                        {
                            if(!isFirst)
                            {
                                preX=list.get(i-1).getCenterX();
                                preY=list.get(i-1).getCenterY();
                            }
                            KeyValue xValue= new KeyValue(list.get(i).centerXProperty(),preX);
                            KeyValue yValue= new KeyValue(list.get(i).centerYProperty(),preY);
                            KeyFrame keyFrame = new KeyFrame(Duration.millis(500),xValue,yValue);
                            timeline.getKeyFrames().add(keyFrame);
                            isFirst=false;
                        }
                        timeline.play();
                    }
            }
               //监听键盘事件
            scene.setOnKeyReleased(new EventHandler<KeyEvent>()
            {
            
               
                public void handle(KeyEvent event)
                {
                    
                    keyCode=event.getText();
                    DoubleProperty arcValue=null;
                    double arcMove = 0;
               
                    
                    switch(keyCode)
                    {
                    case "W":
                    case "w":
                        arcValue=arc.centerYProperty();
                        arcMove=arc.getCenterY()-30;
                        break;
                    case "A":
                    case "a":
                        arcValue=arc.centerXProperty();
                        arcMove=arc.getCenterX()-30;
                        break;
                    case "S":
                    case "s":
                        arcValue=arc.centerYProperty();
                        arcMove=arc.getCenterY()+30;
                        break;
                        
                    case "D":
                    case "d":
                        arcValue=arc.centerXProperty();
                        arcMove=arc.getCenterX()+30;
                        break;
                    }
                    Move move = new Move();
                    move.moveObj(arcValue,arcMove);   
                    
                    
                    
                    Timer timer = new Timer();
                    timer.schedule(new TimerTask()
                    {
                          public void run()
                            {
                                DoubleProperty arcValue=null;
                                double arcMove = 0;
                                
                                switch(keyCode)
                                {
                                case "W":
                                case "w":
                                    arcValue=arc.centerYProperty();
                                    arcMove=arc.getCenterY()-30;
                                    break;
                                case "A":
                                case "a":
                                    arcValue=arc.centerXProperty();
                                    arcMove=arc.getCenterX()-30;
                                    break;
                                case "S":
                                case "s":
                                    arcValue=arc.centerYProperty();
                                    arcMove=arc.getCenterY()+30;
                                    break;
                                    
                                case "D":
                                case "d":
                                    arcValue=arc.centerXProperty();
                                    arcMove=arc.getCenterX()+30;
                                    break;
                                }
                                
                                if(event.getText()!=null)
                                {
                                    move.moveObj(arcValue,arcMove);
                                }
                            }
                     }
                      ,10,100);
                    
                //吃食物
                Timer timer1 = new Timer();
                timer1.schedule(new TimerTask()
                {
               
                    double arcX=arc.getCenterX();
                    double arcY=arc.getCenterY();
                            public void run()
                              {
                                for(int i=0;i<list1.size();i++)
                                {
                                    double cirX=list1.get(i).getCenterX();
                                    double cirY=list1.get(i).getCenterX();
                                    double distance=Math.sqrt((arcX-cirX)*(arcX-cirX)+(arcY-cirY)*(arcY-cirY));
                                    if(distance<30)
                                    {
                                        list.add(list1.get(i));
                                        list1.remove(i);  
                                    }
                                            
                                }
                                 
                                 
                              }
                }
                        ,10,100);
                        
                }//hanndle
                    
                }//listen
         
            );
         
            
         
            g.getChildren().addAll(list);
            g.getChildren().addAll(list1);
            g.getChildren().add(arc);
               
            stage.setScene(scene);
            stage.show();
                    
    }
    public static void main(String[] args) {
        launch(args);
    }
}


蛇不能吃食物？？？
求大神解！！！！

月月姐在吗？？@林月儿
8 回复
#2
林月儿2018-10-03 22:26
没开电脑，等吃完饭帮你看一下
#3
林月儿2018-10-03 23:20
问题蛮多的，变量的命名规范，作用域混淆，代码的缩进，还有一些笔误等等
对自己要求还是要高一点啊！
对了，这个资源关闭没查，stop()好像是能监听到窗体关闭的。你可以查查看确认下
程序代码：
package application2;

import java.util.Arrays;
import java.util.LinkedList;
import java.util.Random;
import java.util.Timer;
import java.util.TimerTask;

import javafx.animation.KeyFrame;
import javafx.animation.KeyValue;
import javafx.animation.Timeline;
import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.input.KeyEvent;
import javafx.scene.paint.Color;
import javafx.scene.shape.Arc;
import javafx.scene.shape.ArcType;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
import javafx.util.Duration;

public class Main extends Application
{
    static String keyCode = null;
    @Override
    public void start(Stage stage)
    {
        Group g = new Group();
        Scene scene = new Scene(g,1024,700);
        LinkedList<Circle> list = new LinkedList<>();
        LinkedList<Circle> foods = new LinkedList<>();
        
        //画食物
        Random r = new Random();
        
        for(int i = 0; i < 10; i++)
        {
            int x = r.nextInt(1009-15+1)+15;
            int y = r.nextInt(685-15+1)+15;
            
            Circle cir  =  new Circle();
            cir.setCenterX(x);
            cir.setCenterY(y);
            cir.setRadius(15);
            cir.setFill(Color.BLACK);
            foods.add(cir);
        }
        //画蛇   
        Arc arc = new Arc();
        arc.setFill(Color.BLACK);
        arc.setCenterX(300);
        arc.setCenterY(200);
        arc.setRadiusX(15);
        arc.setRadiusY(15);
        arc.setStartAngle(45);
        arc.setLength(270);
        arc.setType(ArcType.ROUND);
        
        for(int i = 0; i < 5; i++)
        {
            Circle cir  =  new Circle();
            cir.setCenterX(270-30*i);
            cir.setCenterY(200);
            cir.setRadius(15);
            cir.setFill(Color.BLACK);
            list.add(cir);
        }
        //定义移动
        class Move
        {
            public void moveObj(DoubleProperty arcValue, double arcMove)
            {
                Timeline timeline = new Timeline();
                //head
                KeyValue ARCValue = new KeyValue(arcValue, arcMove);
                KeyFrame ARCkeyFrame = new KeyFrame(Duration.millis(500), ARCValue);
                timeline.getKeyFrames().add(ARCkeyFrame);
                //body
                double preX = arc.getCenterX();
                double preY = arc.getCenterY();
                boolean isFirst = true;
                for(int i = 0; i < list.size(); i++)
                {
                    if(!isFirst)
                    {
                        preX = list.get(i-1).getCenterX();
                        preY = list.get(i-1).getCenterY();
                    }
                    KeyValue xValue = new KeyValue(list.get(i).centerXProperty(), preX);
                    KeyValue yValue = new KeyValue(list.get(i).centerYProperty(), preY);
                    KeyFrame keyFrame = new KeyFrame(Duration.millis(500), xValue, yValue);
                    timeline.getKeyFrames().add(keyFrame);
                    isFirst = false;
                }
                timeline.play();
            }
        }
        Move move = new Move();
        //监听键盘事件
        scene.setOnKeyReleased(new EventHandler<KeyEvent>()
        {
            public void handle(KeyEvent event)
            {
                if(Arrays.asList("W", "w", "A", "a",
                        "S", "s", "D", "d").contains(event.getText())){
                    keyCode = event.getText();
                }
            }//hanndle
        });//listen
        Timer timer = new Timer();
        timer.schedule(new TimerTask()
        {
            public void run()
            {
                if(keyCode == null)
                    return;
                DoubleProperty arcValue = null;
                double arcMove = 0;
               
                switch(keyCode)
                {
                case "W":
                case "w":
                    arcValue = arc.centerYProperty();
                    arcMove = arc.getCenterY()-30;
                    break;
                case "A":
                case "a":
                    arcValue = arc.centerXProperty();
                    arcMove = arc.getCenterX()-30;
                    break;
                case "S":
                case "s":
                    arcValue = arc.centerYProperty();
                    arcMove = arc.getCenterY()+30;
                    break;
                    
                case "D":
                case "d":
                    arcValue = arc.centerXProperty();
                    arcMove = arc.getCenterX()+30;
                    break;
                }
                if(arcValue != null) {
                    move.moveObj(arcValue,arcMove);
                }
            }
        } ,10,100);
        
        //吃食物
        Timer foodTimer = new Timer();
        foodTimer.schedule(new TimerTask()
        {
            public void run()
            {
                double arcX = arc.getCenterX();
                double arcY = arc.getCenterY();
                for(Circle cir : new LinkedList<>(foods))
                {
                    double cirX = cir.getCenterX();
                    double cirY = cir.getCenterY();
                    double distance = Math.sqrt((arcX-cirX)*(arcX-cirX)+(arcY-cirY)*(arcY-cirY));
                    if(distance < 30)
                    {
                        list.add(cir);
                        foods.remove(cir);
                    }
                }
            }
        } ,10,1000);
        g.getChildren().addAll(list);
        g.getChildren().addAll(foods);
        g.getChildren().add(arc);
        
        stage.setScene(scene);
        stage.show();
    }
    @Override
    public void stop() throws Exception {
        System.exit(0);
    }
    public static void main(String[] args) {
        launch(args);
    }
}


[此贴子已经被作者于2018-10-3 23:21编辑过]
#4
渐渐鱼2018-10-05 16:47
回复 3楼 林月儿
月月姐，先前的问题都修改好了，谢谢你的指导。最后还有一个问题，新建了BEGIN类作为开始页面和Again的游戏结束重新开始界面。这两个页面通过Button按钮来监听事件达到转换界面的效果，但是main类也就是游戏的那个要监听arc这个圆弧的坐标来控制页面的转换。这个事件.....额额额，找了好多资料都没办法解决。姐姐有什么好的思路可以解决这个问题吗？
#5
林月儿2018-10-05 18:29
你还在搞这个游戏啊？那试试这个吧
程序代码：
package application2;

import javax.swing.JOptionPane;

public class Begin {
    public static void main(String[] args) {
        if(JOptionPane.showConfirmDialog(null, "开始游戏?")
                == JOptionPane.OK_OPTION) {
            Main.main(null);
        }
    }
}

Again的游戏结束重新开始界面，不确定你的结束条件什么。
至于怎么处理，你得描述清楚。
除了先前的问题，下面这个比较明显的方向问题也要改掉
Timer timer = new Timer();
timer.schedule(new TimerTask()
{
    public void run()
    {
        if(keyCode == null)
            return;
        DoubleProperty arcValue = null;
        double arcMove = 0;
        
        switch(keyCode)
        {
        case "W":
        case "w":
            arc.setRotate(-90);
            arcValue = arc.centerYProperty();
            arcMove = arc.getCenterY()-30;
            break;
        case "A":
        case "a":
            arc.setRotate(180);
            arcValue = arc.centerXProperty();
            arcMove = arc.getCenterX()-30;
            break;
        case "S":
        case "s":
            arc.setRotate(90);
            arcValue = arc.centerYProperty();
            arcMove = arc.getCenterY()+30;
            break;
            
        case "D":
        case "d":
            arcValue = arc.centerXProperty();
            arcMove = arc.getCenterX()+30;
            break;
        }
        if(arcValue != null) {
            move.moveObj(arcValue,arcMove);
        }
    }
} ,10,100);

你这个尾插法感觉挺新颖，之前c板块wmf2014有个头插法的有兴趣可以研究一下
https://bbs.bccn.net/thread-442229-1-1.html
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#6
林月儿2018-10-05 18:37
我该吃饭了，先下啦
#7
渐渐鱼2018-10-06 13:30
回复 6楼 林月儿
月月姐，之前说的那个问题我再重新描述一下。

就是一共三个界面：begin，again和main。

begin是开始界面。就是从begin界面可以进入main游戏类里。

然后main游戏进行过程中如果死亡就结束游戏然后要跳转到again界面。again里有一个按钮可以再次重新开始游戏。

现在begin到main的跳转和again再返回到main都没问题。通过按钮来控制。

但是main里死亡需要通过arc也就是蛇头的坐标来判断，监听蛇头的坐标，如果出了边界，就跳转到again类。这个步骤的实现没有完成。

因为begin和again都是通过按钮来控制跳转，这个就通过坐标 。。鹅鹅鹅。事件处理里似乎没有这个

有什么好的idea没？？
#8
林月儿2018-10-06 14:08
那就按坐标判断啊，src不是有坐标属性吗？
首先判断位置你可以考虑定时任务，因为考虑到游戏进度的监控么
判断条件不就是src的currentx,currenty属性哪~
想多了吧小伙子？
#9
林月儿2018-10-06 14:09
你这个20分就给到我回复去吃饭了
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