java - 如何在draw()方法中使用数组？

Question

我正在 Processing 中制作一个程序(一种与 Java 非常相似的语言)它将我使用 python 排序的数据放入文本文件中，然后添加到处理草图中并将它们显示在可滚动的气泡中。我希望每次释放鼠标按钮时数组索引都会增加一，以便可以通过单击并释放来查看所有歌曲(即我排序的数据)。问题是处理不允许我使用已将文件加载到 draw() 中的数组。方法即使我的 setup()和draw()方法是公开的。它给我的错误是 NullPointerException第 82 行:

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

当它可以在 setup() 中读取文件时，它还说我的文件丢失且无法读取。 。我非常感谢您的帮助。

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!

Answer 1

您的数组在函数 setup() 中被声明为局部变量，因此它们在该函数之外不可见。为了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");
        ...
    }
}