java - 预递增数组对象 (++frequency[i]; ) 是什么意思？

Question

public class ArrayStudentPoll {
    public static void main( String args[] )
    {
       // array of survey responses
       int responses[] = { 1, 2, 6, 4, 8, 5, 9, 7, 8, 10, 1, 6, 3, 8, 6, 
         10, 3, 8, 2, 7, 6, 5, 7, 6, 8, 6, 7, 5, 6, 6, 5, 6, 7, 5, 6, 
         4, 8, 6, 8, 10 };
       int frequency[] = new int[ 11 ]; // array of frequency counters

       // for each answer, select responses element and use that value 
       // as frequency index to determine element to increment
       for ( int answer = 0; answer < responses.length; answer++ )
          ++frequency[ responses[ answer ] ];


       System.out.printf( "%s%10s\n", "Rating", "Frequency" );

       // output each array element's value
       for ( int rating = 1; rating < frequency.length; rating++ )
          System.out.printf( "%6d%10d\n", rating, frequency[ rating ] );
   }
}

这是我在项目中查看的代码。

除了 ++frequency[i]; 这部分我都明白了，其中 frequency 是一个数组而不是一个数字？它到底在做什么？他们写了评论，但我还是没收到。

这是我得到的结果

Rating Frequency
     1         2
     2         2
     3         2
     4         2
     5         5
     6        11
     7         5
     8         7
     9         1
    10         3

Answer 1

++frequency[responses[answer]] 预递增 responses[answer] 数组的第 frequency 元素。

相当于

frequency[responses[answer]] = frequency[responses[answer]] + 1;

顺便说一句，使用后递增 (frequency[responses[answer]]++) 将在此程序中给出相同的结果，因为此代码未使用递增运算符的返回值.