如何在draw（）方法中使用数组？

时间：2014-01-19 23:50:33

标签： java arrays animation processing draw

我正在使用Processing（一种非常类似于Java的语言）创建一个程序，它将使用python排序的数据转换为文本文件，然后添加到处理草图中并以可滚动的气泡显示它们。我希望每次释放鼠标按钮时数组索引都会增加1，这样所有歌曲（即我排序的数据）都可以通过单击和释放来查看。问题是，即使我的draw()和setup()方法都是公共的，处理也不会让我使用我在draw()方法中加载文件的数组。它给我的错误是第82行NullPointerException：

text(songsort[a1],close,15,99,99);

它还表示我的文件在setup()中可以读取时丢失且无法读取。我非常感谢你的帮助。

这是我的代码：

import de.looksgood.ani.*;
import de.looksgood.ani.easing.*;
PFont f;
int x=50;
int i=50;
int y=50;
int far=999;
int mid=666;
int close=333;
int end=1333;
int y1=113;
int far2=999;
int mid2=666;
int close2=333;
int end2=1333;
int y2=339;
int far3=999;
int mid3=666;
int close3=333;
int end3=1333;
int y3=567;
int a1=1;
int a2=2;
int a3=3;
int a4=4;
int b1=1;
int b2=2;
int b3=3;
int b4=4;
int c1=1;
int c2=2;
int c3=3;
int c4=4;

public void setup(){
  size(1333,680);
  smooth();
  f = createFont("Georgia", 32);
  textFont(f);
  textAlign(CENTER, CENTER);
  String[] songsort= loadStrings("songsort.txt");
  String[] artistsort= loadStrings("yearsort.txt");
  String[] yearsort= loadStrings("artistsort.txt");
  println("There are "+songsort.length+artistsort.length+yearsort.length+" lines");

  Ani.init(this);
  Ani.setDefaultEasing(Ani.QUART_IN_OUT);
}

public void draw(){
    background(169);


    fill(123,43,23);
    stroke(0);
    rect(x,1,100,height/3);

    textFont(f);
    textSize(32);
    fill(50);
    text("sorted by year",x,15,100,height/3);

    fill(123,43,23);
    stroke(0);
    ellipse(far,y1,99,99);
    fill(123,43,23);
    stroke(0);
    ellipse(mid,y1,99,99);
    fill(123,43,23);
    stroke(0);
    ellipse(close,y1,99,99);
    fill(123,43,23);
    stroke(0);
    ellipse(end,y1,99,99);

    textFont(f);
    textSize(16);
    fill(255);
    text(songsort[1],close,15,99,99); ///////////// Error here! /////////////


   if((mouseX<1333) && (mouseX>0) && (mouseY>0) && (mouseY<226) && (mousePressed==true)){
     x=x-5;
     end=end-5;
     far=far-5;
     mid=mid-5;
     close=close-5;
   }

    fill(43,123,23);
    stroke(255);
    rect(i,226.66,100,height/3);

    textFont(f);
    textSize(32);
    fill(50);
    text("sorted by song name",i,226.66,100,height/3);

    fill(43,123,23);
    stroke(255);
    ellipse(far2,y2,99,99);
    fill(43,123,23);
    stroke(255);
    ellipse(mid2,y2,99,99);
    fill(43,123,23);
    stroke(255);
    ellipse(close2,y2,99,99);
    fill(43,123,23);
    stroke(255);
    ellipse(end2,y2,99,99);

    if((mouseX<1333) && (mouseX>0) && (mouseY>226.66) && (mouseY<453.34) && (mousePressed==true)){
       i=i-5;
     end2=end2-5;
     far2=far2-5;
     mid2=mid2-5;
     close2=close2-5;
     }

    fill(240,179,93);
    stroke(147);
    rect(y,453.34,100,height/3);

    textFont(f);
    textSize(32);
    fill(50);
    text("sorted by artist",y,453.34,100,height/3);

    fill(240,179,93);
    stroke(147);
    ellipse(far3,y3,99,99);
    fill(240,179,93);
    stroke(147);
    ellipse(mid3,y3,99,99);
    fill(240,179,93);
    stroke(147);
    ellipse(close3,y3,99,99);
    fill(240,179,93);
    stroke(147);
    ellipse(end3,y3,99,99);

   if((mouseX<1333) && (mouseX>0) && (mouseY>453.34) && (mouseY<680) && (mousePressed==true)){
     y=y-5;
     end3=end3-5;
     far3=far3-5;
     mid3=mid3-5;
     close3=close3-5;
   } 
}

void mouseReleased(){
  Ani.to(this, 1.0, "close", 133);
  Ani.to(this, 1.0, "mid", 466);
  Ani.to(this, 1.0, "far", 799);
  Ani.to(this, 1.0, "end", 1133);   
  Ani.to(this, 1.0, "close2", 133);
  Ani.to(this, 1.0, "mid2", 466);
  Ani.to(this, 1.0, "far2", 799);
  Ani.to(this, 1.0, "end2", 1133);   
  Ani.to(this, 1.0, "close3", 133);
  Ani.to(this, 1.0, "mid3", 466);
  Ani.to(this, 1.0, "far3", 799);
  Ani.to(this, 1.0, "end3", 1133);   
}

谢谢！

2 个答案:

答案 0 :(得分：2)

您的数组在函数设置（）中被声明为局部变量，因此它们在此函数之外是不可见的。要使它们在类的其他函数中可见，您应该将它们声明为此类的字段。

public class YourClass {

    private String[] songsort;

    private String[] artistsort;

    private String[] yearsort;

    public void setup() {
        ...
        songsort = loadStrings("songsort.txt");
        artistsort = loadStrings("yearsort.txt");
        yearsort = loadStrings("artistsort.txt");
        ...
    }
}

答案 1 :(得分：1)

以下是您的代码的精简版本：

                                                    //0
public void setup() {                               //1
  String[] songsort = loadStrings("songsort.txt");  //2
}                                                   //3
                                                    //4
public void draw() {                                //5
    text(songsort[1],close,15,99,99);               //6
}                                                   //7

在第2行，您使用songsort声明变量String[] songsort。因为这是方法setup，变量songsort是“局部变量”，只能在该方法中访问。要解决此问题，在第0行声明变量，但仍然在<{1}}方法中初始化，如下所示：

setup

对所有String[] songsort; //0 public void setup() { //1 songsort = loadStrings("songsort.txt"); //2 } //3 //4 public void draw() { //5 text(songsort[1],close,15,99,99); //6 } //7 执行此操作并将其应用于您拥有的代码应如下所示：

String[]

变量import de.looksgood.ani.*; import de.looksgood.ani.easing.*; String[] songsort; String[] artistsort; String[] yearsort; PFont f; int x=50; int i=50; int y=50; int far=999; int mid=666; int close=333; int end=1333; int y1=113; int far2=999; int mid2=666; int close2=333; int end2=1333; int y2=339; int far3=999; int mid3=666; int close3=333; int end3=1333; int y3=567; int a1=1; int a2=2; int a3=3; int a4=4; int b1=1; int b2=2; int b3=3; int b4=4; int c1=1; int c2=2; int c3=3; int c4=4; public void setup() { size(1333,680); smooth(); f = createFont("Georgia", 32); textFont(f); textAlign(CENTER, CENTER); songsort= loadStrings("songsort.txt"); artistsort= loadStrings("yearsort.txt"); yearsort= loadStrings("artistsort.txt"); println("There are "+songsort.length+artistsort.length+yearsort.length+" lines"); Ani.init(this); Ani.setDefaultEasing(Ani.QUART_IN_OUT); } public void draw() { background(169); fill(123,43,23); stroke(0); rect(x,1,100,height/3); textFont(f); textSize(32); fill(50); text("sorted by year",x,15,100,height/3); fill(123,43,23); stroke(0); ellipse(far,y1,99,99); fill(123,43,23); stroke(0); ellipse(mid,y1,99,99); fill(123,43,23); stroke(0); ellipse(close,y1,99,99); fill(123,43,23); stroke(0); ellipse(end,y1,99,99); textFont(f); textSize(16); fill(255); text(songsort[1],close,15,99,99); if((mouseX<1333) && (mouseX>0) && (mouseY>0) && (mouseY<226) && (mousePressed==true)) { x=x-5; end=end-5; far=far-5; mid=mid-5; close=close-5; } fill(43,123,23); stroke(255); rect(i,226.66,100,height/3); textFont(f); textSize(32); fill(50); text("sorted by song name",i,226.66,100,height/3); fill(43,123,23); stroke(255); ellipse(far2,y2,99,99); fill(43,123,23); stroke(255); ellipse(mid2,y2,99,99); fill(43,123,23); stroke(255); ellipse(close2,y2,99,99); fill(43,123,23); stroke(255); ellipse(end2,y2,99,99); if((mouseX<1333) && (mouseX>0) && (mouseY>226.66) && (mouseY<453.34) && (mousePressed==true)) { i=i-5; end2=end2-5; far2=far2-5; mid2=mid2-5; close2=close2-5; } fill(240,179,93); stroke(147); rect(y,453.34,100,height/3); textFont(f); textSize(32); fill(50); text("sorted by artist",y,453.34,100,height/3); fill(240,179,93); stroke(147); ellipse(far3,y3,99,99); fill(240,179,93); stroke(147); ellipse(mid3,y3,99,99); fill(240,179,93); stroke(147); ellipse(close3,y3,99,99); fill(240,179,93); stroke(147); ellipse(end3,y3,99,99); if((mouseX<1333) && (mouseX>0) && (mouseY>453.34) && (mouseY<680) && (mousePressed==true)) { y=y-5; end3=end3-5; far3=far3-5; mid3=mid3-5; close3=close3-5; } } void mouseReleased() { Ani.to(this, 1.0, "close", 133); Ani.to(this, 1.0, "mid", 466); Ani.to(this, 1.0, "far", 799); Ani.to(this, 1.0, "end", 1133); Ani.to(this, 1.0, "close2", 133); Ani.to(this, 1.0, "mid2", 466); Ani.to(this, 1.0, "far2", 799); Ani.to(this, 1.0, "end2", 1133); Ani.to(this, 1.0, "close3", 133); Ani.to(this, 1.0, "mid3", 466); Ani.to(this, 1.0, "far3", 799); Ani.to(this, 1.0, "end3", 1133); } ，songsort和artistsort应该是“字段”，可以在整个标签中访问，在本例中为草图。

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