代碼提供「java.lang.StringIndexOutOfBoundsException：字符串索引超出範圍：14」

Question

下面的代碼給我"java.lang.StringIndexOutOfBoundsException: String index out of range: 14"

請指導我對什麼是錯我的代碼。

public class max_temp { 

    public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> { 

     private final static IntWritable one = new IntWritable(1); 
     private Text word = new Text(); 
     public String y; 
     public String a; 
     public Double t; 

     public void map(Object key, Text value, Context context) throws IOException, InterruptedException { 

      StringTokenizer itr = new StringTokenizer(value.toString()); 
      while (itr.hasMoreTokens()) { 
       word.set(itr.nextToken()); 
       y = word.toString(); 
       a = y.substring(7,14); 
       t = Double.parseDouble((y.substring(35,41).trim())); 

       word.set(a);    

       // 27516201501012.424-156.6171.32-18.3-21.8-20.0-1 9.90.00.00C-19.2-24.5-21.983.973.777.         
       context.write(word, one); 
      } 
     } 
    } 

    public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable> { 
     private IntWritable result = new IntWritable(); 

     public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException { 

      int sum = 0; 
      for (IntWritable val : values) { 
       sum += val.get(); 
      } 
      result.set(sum); 
      context.write(key, result); 
     } 
    } 
} 

Answer 1

如果您連接堆棧跟蹤會更容易。無論如何，問題在於，你調用的長度小於15的String的substring(7,14)。Java不知道該怎麼做，因此會引發異常。

問題出在您的應用程序邏輯上。如果您使用substring(7,14)，則必須確保String足夠長或使用try-catch塊。

try { 
    String s = s.substring(7,14); 
} catch (StringIndexOutOfBoundsException e) { 
    //somehow process the situation in which the string is too short. 
}