[java] How to create a HashMap with two keys (Key-Pair, Value)?

You could create your key object something like this:

public class MapKey {

public  Object key1;
public Object key2;

public Object getKey1() {
    return key1;
}

public void setKey1(Object key1) {
    this.key1 = key1;
}

public Object getKey2() {
    return key2;
}

public void setKey2(Object key2) {
    this.key2 = key2;
}

public boolean equals(Object keyObject){

    if(keyObject==null)
        return false;

    if (keyObject.getClass()!= MapKey.class)
        return false;

    MapKey key = (MapKey)keyObject;

    if(key.key1!=null && this.key1==null)
        return false;

    if(key.key2 !=null && this.key2==null)
        return false;

    if(this.key1==null && key.key1 !=null)
        return false;

    if(this.key2==null && key.key2 !=null)
        return false;

    if(this.key1==null && key.key1==null && this.key2 !=null && key.key2 !=null)
        return this.key2.equals(key.key2);

    if(this.key2==null && key.key2==null && this.key1 !=null && key.key1 !=null)
        return this.key1.equals(key.key1);

    return (this.key1.equals(key.key1) && this.key2.equals(key2));
}

public int hashCode(){
    int key1HashCode=key1.hashCode();
    int key2HashCode=key2.hashCode();
    return key1HashCode >> 3 + key2HashCode << 5;
}

}

The advantage of this is: It will always make sure you are covering all the scenario's of Equals as well.

NOTE: Your key1 and key2 should be immutable. Only then will you be able to construct a stable key Object.

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