Custom HashMap implementation

Question

This question was asked to me in an interview. I think the only way to get best solution is SOF. So the question was \"How would you implement a custom HashMap in java(A

Answer 1

adding just one more approach - how about if we use set instead of hashMap in this way

Create a custom class called pair -

public class Pair  {

    private String key;
    private Object Value;

    public Pair(String key, Object value) {
        this.key = key;
        Value = value;
    }

    public String getKey() {
        return key;
    }

    public Object getValue() {
        return Value;
    }


    @Override
    public int hashCode() {
        return key.hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Pair other = (Pair) obj;
        if (key != other.getKey())
            return false;
        return true;
    }
}

and then you can directly use java Set as Hashmap

 public static void main(String[] args) {

        Set set = new HashSet();

        set.add(new Pair("key1", "val1"));
        set.add(new Pair("key2", "val2"));
        set.add(new Pair("key1", "val3"));

        // you can advanced for loop for looping over set
        for (Pair pair : set) {

        }

        // with java 8 - you can also use streams over it

       // set.stream().filter
       // set.stream().anyMatch
        // and some more methods can be directly used


    }

With Java-8 Stream API - it will enable this to make some more operations easy and fast.

Just adding this as one more possible approach for custom hashmap -