What are variables "offset" & "hash" in String.hashCode()?

Question

I've read that this is the source code for String.hashCode()

   public int hashCode() {
   int h = hash;
   if (h == 0) {
       int off = offset;
       char val[] = value;
       int len = count;

       for (int i = 0; i < len; i++) {
           h = 31*h + val[off++];
       }
       hash = h;
   }
   return h;
   }

My question is, what are "offset" & "hash"? I can tell that "value" is the actual String and "length" is its length, but I don't understand what the other two are.

You could take a look at the rest of the String source code for context. — Oliver Charlesworth
– Oliver Charlesworth, Commented Jul 23, 2016 at 21:35
Read the comments in the source code next to offset and hash. — Andy Turner
– Andy Turner, Commented Jul 23, 2016 at 21:42
/** The offset is the first index of the storage that is used. */ private final int offset; What is storage referring to? — Kartik Chugh
– Kartik Chugh, Commented Jul 23, 2016 at 22:18

Kartik Chugh · Accepted Answer · 2016-07-23 23:54:33Z

0

The offset is the first index of the value[] array of chars of the String. The hash variable is a field for caching the hashCode so as to be more efficient (the hashCode() method only computes the hash if it's current value is 0; else it returns the cached hash)

answered Jul 23, 2016 at 23:54

Kartik Chugh

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