java中的字符串索引超出范围错误答案

【问题标题】：String index out of range error in javajava中的字符串索引超出范围错误
【发布时间】：2016-02-15 03:52:35
【问题描述】：

我正在尝试根据单词中的字母数打印不同的字符串，但我的第二个“if”语句破坏了代码。

import java.util.Scanner;
public class practice {


public static void main(String[] args) {
     Scanner in = new Scanner(System.in);
     System.out.printf("Enter a string: ");       
     String aString = in.next();
     int length = aString.length();

   char first =   aString.charAt(0);
   char second =  aString.charAt(1);
   char third =   aString.charAt(2);
   char fourth =  aString.charAt(3);
   char fifth =   aString.charAt(4);
   char sixth =   aString.charAt(5);
   char seventh = aString.charAt(6);

  if (length == 7) {
     System.out.println(String.format("Line 1: %s %s %s %s ", first, third, fifth, sixth));
     System.out.println(String.format("Line 2: %s %s %s ", second, fourth, sixth));
     System.out.println(String.format("Line 3: %s %s %s %s ", seventh, fifth, third, first));
  }
  else {
   if (length < 7) {
     System.out.println("the length is less than 7");
   }
      }
}

}

如果我输入的单词少于 7 个字母，我只会收到一条错误消息，显示“字符串索引超出范围：6”。我该如何解决这个问题？

【问题讨论】：

粗略看，如果您的输入没有第 7 个字符，我相信是 char seventh = aString.charAt(6) 行中断。
把 char 放在首位 = aString.charAt(0); char second = aString.charAt(1);第三个字符 = aString.charAt(2); char 第四 = aString.charAt(3);第五个字符 = aString.charAt(4); char 第六 = aString.charAt(5);第七个字符 = aString.charAt(6);如果在里面
嘿，成功了，非常感谢！

标签： java string if-statement

【解决方案1】：

因为我不知道确切的要求，所以我刚刚解决了 coede 下面的错误检查

import java.util.Scanner;
public class practice {


public static void main(String[] args) {
 Scanner in = new Scanner(System.in);
 System.out.printf("Enter a string: ");
 String aString = in.next();
 int length = aString.length();


  if (length == 7) {
   char first =   aString.charAt(0);
   char second =  aString.charAt(1);
   char third =   aString.charAt(2);
   char fourth =  aString.charAt(3);
   char fifth =   aString.charAt(4);
   char sixth =   aString.charAt(5);
   char seventh = aString.charAt(6);
 System.out.println(String.format("Line 1: %s %s %s %s ", first, third, fifth, sixth));
 System.out.println(String.format("Line 2: %s %s %s ", second, fourth, sixth));
 System.out.println(String.format("Line 3: %s %s %s %s ", seventh, fifth, third, first));
}
else {
if (length < 7) {
 System.out.println("the length is less than 7");
}
  }
}

}

【讨论】：

【解决方案2】：

首先检查length，然后访问字符。此外，您可以使用printf（而不是String.format 和println）。类似的东西

if (length >= 7) {
     char first =   aString.charAt(0);
     char second =  aString.charAt(1);
     char third =   aString.charAt(2);
     char fourth =  aString.charAt(3);
     char fifth =   aString.charAt(4);
     char sixth =   aString.charAt(5);
     char seventh = aString.charAt(6);

     System.out.printf("Line 1: %s %s %s %s%n", first, third, fifth, sixth);
     System.out.printf("Line 2: %s %s %s%n", second, fourth, sixth);
     System.out.printf("Line 3: %s %s %s %s%n", seventh, fifth, third, first);
 } else {
     System.out.println("the length is less than 7");
 }

【讨论】：

【解决方案3】：

我打赌你输入了一个 6 个字母的单词。

这是因为你的线路：

char seventh = aString.charAt(6); // It tries to look for a 7th position in a String that has only six positions

我会将所有的 char 赋值放入 if:

public static void main(String[] args) {
 Scanner in = new Scanner(System.in);
 System.out.printf("Enter a string: ");       
 String aString = in.next();
 int length = aString.length();


  if (length == 7) {
       char first =   aString.charAt(0);
       char second =  aString.charAt(1);
       char third =   aString.charAt(2);
       char fourth =  aString.charAt(3);
       char fifth =   aString.charAt(4);
       char sixth =   aString.charAt(5);
       char seventh = aString.charAt(6);

     System.out.println(String.format("Line 1: %s %s %s %s ", first, third, fifth, sixth));
     System.out.println(String.format("Line 2: %s %s %s ", second, fourth, sixth));
     System.out.println(String.format("Line 3: %s %s %s %s ", seventh, fifth, third, first));
  }
  else {
    if (length < 7) {
        System.out.println("the length is less than 7");
    }
  }
}

【讨论】：

【解决方案4】：

试试下面的代码，它更通用。

            import java.util.Scanner;
            public class practice {


            public static void main(String[] args) {
                 Scanner in = new Scanner(System.in);
                 System.out.printf("Enter a string: ");       
                 String aString = in.next();
                 char[] charArr=new char[10];
                 int length = aString.length();
            for(int i=0;i<length;i++){
                charArr[i] =   aString.charAt(i);
            }

              if (length == 7) {
                 System.out.println(String.format("Line 1: %s %s %s %s ", charArr[0], charArr[2], charArr[4], charArr[5]));
                 System.out.println(String.format("Line 2: %s %s %s ", charArr[1], charArr[3], charArr[5]));
                 System.out.println(String.format("Line 3: %s %s %s %s ", charArr[6], charArr[4], charArr[2], charArr[0]));
              }
              else {
               if (length < 7) {
                 System.out.println("the length is less than 7");
               }
                  }
            }

            }

【讨论】：