Can someone please explain me the code for the hashmap get(key) method?

Question

Inside the get(Object key) method of Java , there is a piece of code which I am not able to understand.

I know how the get(key) method works even in case when hashcode is same for two object.

But the below piece of code I am unable to understand.

for (Entry<K,V> e = table[indexFor(hash, table.length)];
              e != null;
              e = e.next) {
             Object k;
             if (e.hash == hash && ((k = e.key) == key || key.equals(k)))
                 return e.value;
         }

Can someone explain. Thanks

Answer 1

HashMap works with Hash bucket algorithm . And Hash buckets are arranged as array which the HashMap class calls as table . So the for loop starts with the first element of the hash bucket which holds the key

Entry<K,V> e = table[indexFor(hash, table.length)

here the hash represents the hash index of that bucket

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for loop will run till there are elements in the bucket ( e != null )

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for loop will iterate like e = e.next , that is, moving to next element in the bucket until match is found

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Now, once the hash bucket is found, the method should return the exact Entry whose key matches the passed key . Now this matching is done by either references matching ( == ) or equals matching (k = e.key) == key || key.equals(k) (k = e.key) == key || key.equals(k)

if the matching happens then the key is returned else the method will return null