Question

错误是字符串索引超出范围：0。老实说，我甚至不知道我正在做的事情是否正确。

我必须创建一个wholeName方法和一个初始方法。他们的名字不言而喻，几乎整个名称根据用户给我的内容打印出名称。如果他们只给了我一个名字，那就是我要回来的全部。

缩写是相同的。它从名称输入中获取第一个字母，仅返回首字母。像约翰李史密斯将是J.L.S。

任何人都可以帮我理解错误吗？如果你不能说我只是一个初学者。

我有一个返回错误的测试程序 java.lang.StringIndexoutofboundexception：字符串索引超出范围：0 at java.lang.String.charAt（String.java:658） at PersonName.Initials（PersonName.java:131）atTestPersonName2.testOneName（TestPersonName2.java:50）

import java.util.StringTokenizer;

public class PersonName
{

   private int numberOfNames ;
    private String firstName;
    private String middleName;
    private String lastName;
    private String suffixName;


        PersonName(){
        firstName=""; 
        middleName=""; 
        lastName=""; 
        suffixName=""; 
        numberOfNames=0;

    }
    public String getFirstName(){

        return firstName;
    }
    public String getMiddleName(){
        return middleName;
    }
    public String getLastName(){
        return lastName;
    }
    public String getSuffixName(){
        return suffixName;
    }
    public void setFirstName(String f){
        if((f.length() == 0) && (firstName.length() == 0)){
          numberOfNames = numberOfNames;   
        }else if(( f.length() > 0) && (firstName.length() == 0)){
            numberOfNames++;
        }
        firstName = f;
    }
    public void setMiddleName(String m){
         if((m.length() == 0) && (middleName.length() == 0)){
          numberOfNames = numberOfNames;   
        }else if(( m.length() > 0) && (middleName.length() == 0)){
            numberOfNames++;
        }
        middleName = m;
    }
    public void setLastName(String l){
         if((l.length() == 0) && (lastName.length() == 0)){
          numberOfNames = numberOfNames;   
        }else if(( l.length() > 0) && (lastName.length() == 0)){
            numberOfNames++;
        }
        lastName = l;
    }
    public void setSuffixName(String s){
        if((s.length() == 0) && (suffixName.length() == 0)){
          numberOfNames = numberOfNames;   
        }else if(( s.length() > 0) && (suffixName.length() == 0)){
            numberOfNames++;
        }
        suffixName = s;
    }
    public int getNumberOfNames(){

        return numberOfNames;
    }
        PersonName(String wholename)
    {   firstName=""; middleName=""; lastName=""; suffixName=""; numberOfNames=0;

        // store the name passed in to the method
       final int MAXNAMES = 4;
        String [] words = new String [MAXNAMES];
        String testname=wholename;
         // initialize number of names found
        int numnames=0;
         // on each iteration remove one name
       StringTokenizer st = new StringTokenizer(wholename);
       while (st.hasMoreTokens()) {
         words[numnames++]=st.nextToken();
     }

     if (numnames ==1)
      {  setFirstName(words[0]);}
     else if (numnames == 2)
      {  setFirstName(words[0]);
        setLastName(words[1]);
      }
     else if (numnames == 3)
      {  setFirstName(words[0]);
        setMiddleName(words[1]);
        setLastName(words[2]);
      }
     else if (numnames == 4)
      {  setFirstName(words[0]);
        setMiddleName(words[1]);
        setLastName(words[2]);
        setSuffixName(words[3]);

      }

    }
    public String EntireName(){
         String EntireName = " ";
        //String EntireName = getFirstName() + " " + getMiddleName() + " " + getLastName() + " " + getSuffixName();
        if(getNumberOfNames() == 0){
            EntireName = " ";
        }else if(getNumberOfNames() == 1){
            EntireName = getFirstName();
        }else if(getNumberOfNames() == 2){
            EntireName = getFirstName() + " " + getMiddleName();
        }else if(getNumberOfNames() == 3){
            EntireName = getFirstName() + " " + getMiddleName() + " " + getLastName();
        }else {
            EntireName = getFirstName() + " " + getMiddleName() + " " + getLastName() + " " + getSuffixName();
        }
        return EntireName;
    }
    public String Initials(){
        String f = getFirstName(); 
        char fChar = f.charAt(0);

        String m = getMiddleName();
        char mChar = m.charAt(0);

        String l = getLastName();
        char lChar = l.charAt(0);

        String s = getSuffixName();
        char sChar = s.charAt(0);

        String initial = " ";

          if(getNumberOfNames() == 0){
            initial = " ";
        }else if(getNumberOfNames() == 1){
            initial = fChar + ".";
        }else if(getNumberOfNames() == 2){
            initial = fChar + "." + mChar + ".";
        }else if(getNumberOfNames() == 3){
            initial = fChar + "." + mChar + "." + lChar + ".";
        }

        //String initial = fChar + "." +  mChar + "." + lChar ;
       return initial; 
    }
}

Answer 1

调用该函数时，firstname为空; 现在在函数中，语句

  String f = getFirstName(); 
  char fChar = f.charAt(0);

已执行。由于f为空（firstName =“”;最初已完成），因此fChar会给出该异常。

将其更新为：

    String s = getSuffixName();
    char sChar = s.charAt(0);

    String initial = " ";

      if(getNumberOfNames() == 0){
        initial = " ";
    }else if(getNumberOfNames() == 1){
        String f = getFirstName(); 
        char fChar = f.charAt(0);
        initial = fChar + ".";
    }else if(getNumberOfNames() == 2){
         String f = getFirstName(); 
         char fChar = f.charAt(0);
         String m = getMiddleName();
         char mChar = m.charAt(0);
         initial = fChar + "." + mChar + ".";
    }else if(getNumberOfNames() == 3){
         String f = getFirstName(); 
         char fChar = f.charAt(0);
         String m = getMiddleName();
         char mChar = m.charAt(0);
         String l = getLastName();
         char lChar = l.charAt(0);
        initial = fChar + "." + mChar + "." + lChar + ".";
    }

<强>注释：

请注意，在代码中，如果getNumberOfNames（）== 1，则假设它是firstname。确保这始终有效。如果没有，那么你会收到错误。

Answer 2

马纳斯打败了我。但是，我也会检查你的set方法（即setFirstName（））

public void setFirstName(String f){
    if((f.length() == 0) && (firstName.length() == 0)){
      numberOfNames = numberOfNames;   
    }else if(( f.length() > 0) && (firstName.length() == 0)){
        numberOfNames++;
    }
    firstName = f; // FIRST NAME IS SET OUTSIDE OF CONDITION, WHETHER f.length() == 0 OR NOT
}

此外，您的numberOfNames计数器存在缺陷。如果只设置了中间名，计数器将增加1但是，将返回firstName而不是middle。尝试重新思考逻辑并重构代码

祝你好运：）

我一直收到一个String out of bounds错误，有人可以帮我修复我的代码吗？

2 个答案: