java.lang.NullPointerException，在Processing中有一个自定义类

时间：2015-03-20 00:35:02

标签： java processing

好吧，我是编程的新手，所以我没有很清楚的基础知识（我的英语也很糟糕）。当我开始使用这段代码时，我希望它能够绘制一些点，让它们保持移动状态，如果它们比它们之间的X更近，那么画一条线。但是我想让它变得有点复杂，然后添加另一个类，它不打算与其他类交互并画一个圆圈，旁边有一些，约束在一个矩形内（我试图将它们限制在一个圆圈内）但是......现在我的脑袋太多了。嗯，问题是我认为代码是“清除”，至少对于PC来说，我不知道为什么我得到这个“java.lang.NullPointerException”错误，因为它没有显示我错误的地方。

非常感谢任何帮助。

//Test nº1. An array of spheres which are randomly moving, connected between them if the distance is less than 50p.
//The spheres' starting position are determined by the red(x) and green(y) color space from colordata from images.


int[] tots = {#2d2a33, #8e8397, #160e19, #8263a9, #0f1723, #737a86, #2d2a33, #8e8497, #15101c, #965555, #1a2940, #9b7873, #080b12, #272b41, #211f33, #8b6659,
            #070719, #4c5985, #423444, #9c8696, #1a2d13, #799078, #30160e, #da9c7b, #2c2e3a, #6d798e, #28474f, #b63f10, #040c1a, #cf6c24, #442036, #a87d99,
            #19191a, #756d6e, #1a2828, #94b1a2, #060c15, #6d98c1, #284062, #9ab9be, #121720, #abb7c5, #6e6b9b, #282033};

//--Malla--

float xo, yo;

int numMalla = 200;

Malla[] ma = new Malla [numMalla]; 

float x;
float y;
float angle = 0.0; // Direction of motion  
//float speed = random(0.2, 0.8); // Speed of motion

float diameter = 0.0;

//----

//--Errant--

int numPiEr = 10;
int e;

float xoEr = width/2;
float yoEr = height/2;
float xoPiEr = xoEr;
float yoPiEr = yoEr;
float cRotO = 0;

Errant ccEr;
//Errant clEr;
Errant[] piEr = new Errant [numPiEr];
//----

void setup() {
//--Malla--
//coords mapping into the original position
xo = map( (tots[int(random(0,tots.length))]& 0xFF0000)>>16, 0, 255, 0, width);
yo = map( (tots[int(random(0,tots.length))]& 0x00FF00)>>8, 0, 255, 0, height);
//----  

size(1024, 768,P2D);
background(0);
smooth();
frameRate(25);
//float rad = random(5.0,150.0);

//--Malla--
for (int i = 0; i < ma.length; i++) {
ma[i] = new Malla(random(10,width-10),random(10,height-10),angle);

}
//----
//--Errant--

Errant ccEr = new Errant (xoEr, yoEr, cRotO);
//Errant clEr = new Errant (xoEr, yoEr, cRotO);

for (int e = 0; e < piEr.length; e++) {
  piEr[e] = new Errant(xoPiEr, yoPiEr, cRotO);
}

//----

}


void draw() {

  background(0);

  for (int i = 0; i < ma.length; i++) {
    ma[i].maMove();
    for (int j = i + 1; j < ma.length; j++) {
      if (ma[i].nearAnotherMalla(ma[j])) {
        ma[i].highlight();
      }
    }
    ma[i].display();
  } 

  for (int e = 0; e < piEr.length; e++) {
    piEr[e].piErMove();
    piEr[e].piErDisplay();

  }
  ccEr.erMove();
  ccEr.errDisplay();
}



class Malla {

float x,y;
float diameter;
float speedX, speedY;
float angle;
//int temps;
//color c = color(255);
Malla[] nearMalla = new Malla[numMalla];

//----

  Malla(float xpos, float ypos, float dir) {

  xo = x;
  yo = y;

  x = xpos;
  y = ypos;
  //speedX = random(-0.2, 0.2);
  //speedY = random(-0.2, 0.2);
  speedX = random(-2, 2);
  speedY = random(-2, 2);
  //temps=0;
  //diameter = random(5, 13);
  diameter = 2.5;
  angle = dir;

}

//----

void maMove() {

 /*  if(temps==10){
  speedX = random(-2, 2);
  speedY = random(-2, 2);
  temps=0;
   }
   ++temps;*/

   if(x+diameter >= width+20) {
      speedX = -speedX;
    }  
    else if(x+diameter <= -20) {
      speedX = -speedX;
    }

    if(y+diameter >= height+20) {
      speedY = -speedY;  
    }
    else if(y+diameter <= -20) {
       speedY = -speedY;
    }

    // angle += random(-0.13, 0.13);
/* x += speedX;
 y += speedY;*/

     angle += random(-0.13, 0.13);

    x += cos(angle) * speedX;
    y += sin(angle) * speedY; 
}

//----

void highlight() {
  //c = color(255,100);
  stroke(255,1);
  for (int i = 0; i < ma.length; i++) {
  if (nearMalla[i] != null) {

    line(x, y, nearMalla[i].x, nearMalla[i].y);
  }
}
 }

//----

void display() {
  //stroke(c);
  noStroke();
  //noFill();
  fill(255);
  ellipse(x,y,diameter,diameter);
  //c = color(0);
}

//----

 boolean nearAnotherMalla(Malla b) {
   boolean near = dist(x,y,b.x,b.y) <= 60;
    for (int i = 0; i < ma.length; i++) {
   if (near) {
       nearMalla[i] = b;
   } 
   else {
     nearMalla[i] = null;
   }
   }
   return near;

 }
}

这是不起作用的，单个对象

class Errant {

  float xEr, yEr, xPiEr, yPiEr, cRot, velEr, velErX, velErY, velPiEr,  velPiErX, velPiErY;
  int ccDiam, clDiamX, clDiamY, piErDiam;


  Errant[] nearPiEr = new Errant[numPiEr];

  //----

  Errant(float xEr, float yEr, float cRot) {

    ccDiam = 15;
    clDiamX = 80;
    clDiamY = 70;

    xEr = xoEr;
    yEr = yoEr;

    xPiEr = random((xEr-20),(xEr+20));
    yPiEr= random((yEr-20), (yEr+20));

    cRot = cRotO;

    velEr = random(-3,3);
    velEr = velErX = velErY;
    velPiEr = random(-1.5,1.5);
    velPiEr = velPiErX = velPiErY;
  }


  void erMove() {

    if(xEr+clDiamX >= width+100) {
      velErX = -velErX;
    }  
    else if(xEr+clDiamX <= -100) {
      velErX = -velErX;
    }

    if(yEr+clDiamX >= height+100) {
      velErY = -velErY;  
    }
    else if(yEr+clDiamX <= -100) {
       velErY = -velErY;
    }

    cRot += random(-0.2,0.2);
    xEr = cos(cRot)*velEr;
    yEr = sin(cRot)*velEr;

  }

  void piErMove() {

    if(xPiEr >= xEr+clDiamX) {
      velErX = -velPiErX;
    }  
    else if(xPiEr <= xEr-clDiamX) {
      velErX = -velPiErX;
    }

    if(yPiEr >= yEr+clDiamY) {
      velErY = -velPiErY;  
    }
    else if(yPiEr <= xEr-clDiamY) {
       velErY = -velPiErY;
    }

    xPiEr = cos(cRot)*velPiEr;
    yPiEr = sin(cRot)*velPiEr;

  }

  void errDisplay () {
    noStroke();
    fill(#EFE4B0, 70);

    ellipse(xEr, yEr, 10, 10);
  }

  void piErDisplay () {
    fill(#EFC6B0, 50);

    ellipse(xPiEr, yPiEr, 1, 1);
  }

}

提前致谢，girald0。

这是我在控制台中收到的错误消息：

java.lang.RuntimeException: java.lang.NullPointerException
    at com.jogamp.common.util.awt.AWTEDTExecutor.invoke(AWTEDTExecutor.java:58)
    at jogamp.opengl.awt.AWTThreadingPlugin.invokeOnOpenGLThread(AWTThreadingPlugin.java:103)
    at jogamp.opengl.ThreadingImpl.invokeOnOpenGLThread(ThreadingImpl.java:206)
    at javax.media.opengl.Threading.invokeOnOpenGLThread(Threading.java:172)
    at javax.media.opengl.Threading.invoke(Threading.java:191)
    at javax.media.opengl.awt.GLCanvas.display(GLCanvas.java:541)
    at processing.opengl.PJOGL.requestDraw(PJOGL.java:688)
    at processing.opengl.PGraphicsOpenGL.requestDraw(PGraphicsOpenGL.java:1651)
    at processing.core.PApplet.run(PApplet.java:2256)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
    at punts_moviment_mapejats2.draw(punts_moviment_mapejats2.java:111)
    at processing.core.PApplet.handleDraw(PApplet.java:2386)
    at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
    at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
    at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
    at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
    at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
    at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
    at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$200(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)

1 个答案:

答案 0 :(得分：1)

Processing首先运行sketch（）方法，然后连续运行draw（）方法。如果你不想根据我对你的问题的评论深入挖掘实际的.java源代码，你可以开始在设置和绘图中评论东西，直到你的草图再次运行，这将指向违规行。

问题似乎是第94行：

ccEr.erMove();

ccEr为空。

您可以在第37行定义此变量两次：

Errant ccEr;

再一次在第63行：

Errant ccEr = new Errant (xoEr, yoEr, cRotO);

处理似乎只考虑第一个（第37行），并且在那个实际上你没有创建对象，只是一个名为ccEr的变量，里面没有任何内容（如果你愿意，则为null）< / p>

现在，我评论第37行，然后根本找不到变量！这让我感到困惑，因为我知道你可以定义＆＃34; global＆＃34;到处变量。显然，Processing的内部hocus-pocus已经改变，因此您必须在设置（）...上传输第63行（您定义和创建ccEr的位置）...

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