CODEWITHSUNDEEP
javadata-structures
user3535029
user3535029

Reputation:

How do I check if a key in a hash table has a certain hashcode?

For example, ht.put("A", 0); has a hashcode of 65. How would I search the hashtable to see whether a key with a hashcode of 65 exists?

Upvotes: 0

Views: 221

Answers (2)

Alexey Malev
Alexey Malev

Reputation: 6533

To achieve that, you have to traverse map's entrySet() and check each key()'s hashCode() against some value you want to check presense, 65 in your example:

Map<String, String> map = new HashMap<String, String>();

public boolean hashCodePresent(int hashCode) {
    for (Map.Entry<String, String> mapEntry : map.entrySet()) {
        if (mapEntry.getKey().hashCode() == hashCode) {
            return true;
        }
    }

    return false;
}

Upvotes: 0

nanofarad
nanofarad

Reputation: 41271

You can construct a class whose hashcode is the code in question:

public class HashCodeWrapper {
    private final int hashCode;
    public HashCodeWrapper(int hashCode){
        this.hashCode = hashCode;
    }
    @Override
    public int hashCode(){
        return hashCode;
    }
    @Override
    public boolean equals(Object o){ return this.hashCode == o.hashCode(); }
}

You can then pass this into Hashtable#get(Object).

Note that there may be hash collisions, in this case the result will be any with this hashcode. However, with a null-check this is more than enough to check for the existence of this hashcode.

Upvotes: 1

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