Java JApplet因阵列的for循环而崩溃

这是我的第一篇帖子，所以对我放松点。 我正在做一些简单的工作，在整个项目中我不需要任何帮助或建议。 基本上，当我对for循环进行注释时，整个过程都能正常工作：

          for(int i=0;i<words.length;i++)
          {
          textArea.append(words[i] + "\n");
          }

文件2，这是分析java文件：

    package Assignment2;


    public class stringAnalyser{
       //static String inputArray[]= {"Tim","John","Craig", "Andrew", "Bob", "Tom",                          "Phillipa","Billie-Bob"};
       private String inputString = "";

       private String removedCharString;//will store the string with removed chars
       private String array3="",array4="", array5="", array6="", array7="", array8="",         array9="", array10="",array11="",
               array12="",array13="",array14="",array15=""; 
       private String[] sendString;
       private int count=0;
    //will add the words with the appropriate length to a string for printing

   public void setText(String input)
   {
       this.inputString=input;
   }
  public String showme()
  {
      return "Think is not difficult believe is the word and look at me I am the great evidence!!!";

  }


public  void output()
{
int three=0, four=0, five=0, six=0, seven=0, eight=0, nine=0, ten=0,eleven=0,twelve=0,thirt=0,fort=0,fift=0;
// these ints will count how many times the words relevent length have accoured in a string
   String w[];
   removedCharString = inputString.replaceAll("[^a-zA-Z\\s]", "");//remove chars
   w=removedCharString.split(" ");
   this.sendString=new String[w.length];

   for (String retval: removedCharString.split(" "))//split at any spaces
  {

   if (retval.length()==3){
       three++;
       array3 = array3 + retval + ", ";

     }//if 3
    if (retval.length()==4){
        four++;
       array4 = array4 + retval + ", "; 
     }//if 4
     if (retval.length()==5){
         five++;
       array5 = array5 + retval + ", "; 
     }//if 5
      if (retval.length()==6){
          six++;
       array6 = array6 + retval + ", ";              
     }//if 6
      if (retval.length()==7){
          seven++;
       array7 = array7 + retval + ", ";              
     }//if 7
      if (retval.length()==8){
          eight++;
       array8 = array8 + retval + ", ";              
     }//if 8
      if (retval.length()==9){
          nine++;
       array9 = array9 + retval + ", ";              
     }//if 9
      if (retval.length()==10){
          ten++;
       array10 = array10 + retval + ", ";              
     }//if 10
      if (retval.length()==11){
          eleven++;
       array11 = array11 + retval + ", ";              
     }//if 10

      if (retval.length()==12){
          twelve++;
       array12 = array12 + retval + ", ";              
     }//if 10

      if (retval.length()==13){
          thirt++;
       array13 = array13 + retval + ", ";              
     }//if 10

      if (retval.length()==14){
          fort++;
       array14 = array14 + retval + ", ";              
     }//if 10

      if (retval.length()==15){
          fift++;
       array15 = array15 + retval + ", ";              
     }//if 10




  }//for string retval




    // print the results
   System.out.println(inputString);
   if (three!=0){
       count++;
       sendString[count]="There are: "+three+" three letter word/s; "+array3;
    System.out.println("There are: "+three+" three letter word/s; "+array3);}
   if (four!=0){
       count++;
       sendString[count]="There are: "+four+" four letter word/s; "+array4;
    System.out.println("There are: "+four+" four letter word/s; "+array4);}
   if (five!=0){
    System.out.println("There are: "+five+" five letter word/s; "+array5);}
   if (six !=0){
    System.out.println("There are: "+six+" six letter word/s; "+array6);}
   if (seven !=0){
    System.out.println("There are: "+seven+" seven letter word/s; "+array7);}
   if (eight!=0){
    System.out.println("There are: "+eight+" eigth letter word/s; "+array8);}
   if (nine!=0){
    System.out.println("There are: "+nine+" nine letter word/s; "+array9);}
   if (ten!=0){
    System.out.println("There are: "+ten+" ten letter word/s;"+array10);}
    if (eleven!=0){
    System.out.println("There are: "+eleven+" eleven letter word/s;"+array11);}
     if (twelve!=0){
    System.out.println("There are: "+twelve+" twelve letter word/s;"+array12);}
      if (thirt!=0){
    System.out.println("There are: "+thirt+" thirteen letter word/s;"+array13);}
       if (fort!=0){
    System.out.println("There are: "+fort+" forteen letter word/s;"+array14);}
        if (fift!=0){
    System.out.println("There are: "+fift+" fifteen letter word/s;"+array15);}

        }//output
      public String[] sendBack()
      {
          return this.sendString;
      }
        public static void main(String []args)
        {
            stringAnalyser a=new stringAnalyser();
            a.output(); 

        }//close main


    }//class`

---

提前感谢您的所有输入。

在

btenter.addActionListener

中，您似乎只调用

tim.setText（inputString）。但是您从不调用
output（）
或分析器上任何其他需要处理输入的方法。因此，
tim.sendBack（）
返回
null
stringanalyzer.sendString
仅在
output（）
内初始化。在此之前，它将保持
null
。所以
words.length
触发
NullPointerException
，因为
words
数组是
null

所发布代码的缩进和命名有时有点难以理解。请参阅Java，特别是第节。大多数工具都可以为您自动缩进代码，即Eclipse中的ctrl+shift+f
 欢迎来到SO！请只张贴相关代码（如果我们需要更多，我们会询问）。另外，请发布哪一行崩溃，以及错误类型。“NetBeans一直告诉我将其更改为增强的for循环，但当我这样做时崩溃”——这只是一个建议。你不必这么做。还要定义“崩溃”谢谢你在这方面的帮助，很抱歉在回复中等待了很长时间。这个项目确实完成了，我似乎对我试图实现的目标和我试图实现它的方式有很大的误解。再次感谢您的帮助和方便的ctrl+shift+f快捷方式。提姆。
    package Assignment2;


    public class stringAnalyser{
       //static String inputArray[]= {"Tim","John","Craig", "Andrew", "Bob", "Tom",                          "Phillipa","Billie-Bob"};
       private String inputString = "";

       private String removedCharString;//will store the string with removed chars
       private String array3="",array4="", array5="", array6="", array7="", array8="",         array9="", array10="",array11="",
               array12="",array13="",array14="",array15=""; 
       private String[] sendString;
       private int count=0;
    //will add the words with the appropriate length to a string for printing

   public void setText(String input)
   {
       this.inputString=input;
   }
  public String showme()
  {
      return "Think is not difficult believe is the word and look at me I am the great evidence!!!";

  }


public  void output()
{
int three=0, four=0, five=0, six=0, seven=0, eight=0, nine=0, ten=0,eleven=0,twelve=0,thirt=0,fort=0,fift=0;
// these ints will count how many times the words relevent length have accoured in a string
   String w[];
   removedCharString = inputString.replaceAll("[^a-zA-Z\\s]", "");//remove chars
   w=removedCharString.split(" ");
   this.sendString=new String[w.length];

   for (String retval: removedCharString.split(" "))//split at any spaces
  {

   if (retval.length()==3){
       three++;
       array3 = array3 + retval + ", ";

     }//if 3
    if (retval.length()==4){
        four++;
       array4 = array4 + retval + ", "; 
     }//if 4
     if (retval.length()==5){
         five++;
       array5 = array5 + retval + ", "; 
     }//if 5
      if (retval.length()==6){
          six++;
       array6 = array6 + retval + ", ";              
     }//if 6
      if (retval.length()==7){
          seven++;
       array7 = array7 + retval + ", ";              
     }//if 7
      if (retval.length()==8){
          eight++;
       array8 = array8 + retval + ", ";              
     }//if 8
      if (retval.length()==9){
          nine++;
       array9 = array9 + retval + ", ";              
     }//if 9
      if (retval.length()==10){
          ten++;
       array10 = array10 + retval + ", ";              
     }//if 10
      if (retval.length()==11){
          eleven++;
       array11 = array11 + retval + ", ";              
     }//if 10

      if (retval.length()==12){
          twelve++;
       array12 = array12 + retval + ", ";              
     }//if 10

      if (retval.length()==13){
          thirt++;
       array13 = array13 + retval + ", ";              
     }//if 10

      if (retval.length()==14){
          fort++;
       array14 = array14 + retval + ", ";              
     }//if 10

      if (retval.length()==15){
          fift++;
       array15 = array15 + retval + ", ";              
     }//if 10




  }//for string retval




    // print the results
   System.out.println(inputString);
   if (three!=0){
       count++;
       sendString[count]="There are: "+three+" three letter word/s; "+array3;
    System.out.println("There are: "+three+" three letter word/s; "+array3);}
   if (four!=0){
       count++;
       sendString[count]="There are: "+four+" four letter word/s; "+array4;
    System.out.println("There are: "+four+" four letter word/s; "+array4);}
   if (five!=0){
    System.out.println("There are: "+five+" five letter word/s; "+array5);}
   if (six !=0){
    System.out.println("There are: "+six+" six letter word/s; "+array6);}
   if (seven !=0){
    System.out.println("There are: "+seven+" seven letter word/s; "+array7);}
   if (eight!=0){
    System.out.println("There are: "+eight+" eigth letter word/s; "+array8);}
   if (nine!=0){
    System.out.println("There are: "+nine+" nine letter word/s; "+array9);}
   if (ten!=0){
    System.out.println("There are: "+ten+" ten letter word/s;"+array10);}
    if (eleven!=0){
    System.out.println("There are: "+eleven+" eleven letter word/s;"+array11);}
     if (twelve!=0){
    System.out.println("There are: "+twelve+" twelve letter word/s;"+array12);}
      if (thirt!=0){
    System.out.println("There are: "+thirt+" thirteen letter word/s;"+array13);}
       if (fort!=0){
    System.out.println("There are: "+fort+" forteen letter word/s;"+array14);}
        if (fift!=0){
    System.out.println("There are: "+fift+" fifteen letter word/s;"+array15);}

        }//output
      public String[] sendBack()
      {
          return this.sendString;
      }
        public static void main(String []args)
        {
            stringAnalyser a=new stringAnalyser();
            a.output(); 

        }//close main


    }//class`