Hashmap get(key) returns null even when the value is present

I'm trying to save datas in a hash map and retrieve it. The value corresponding to the key is present and it still returns null. I have implemented the equals() and hashCode() methods also.

ArrayList<Friends> friendsArrayList = new ArrayList<Friends>();
HashMap<Friends,ArrayList<FriendDetails>> friendDetailsHashMap = new HashMap<Friends, ArrayList<FriendDetails>>();
int mSelectedIndex = 0;
...
Friends f = friendsArrayList.get(mSelectedIndex);
ArrayList<MeterGroups> temp2 = friendDetailsHashMap.get(mp); //<== This is where it returns null

My ObjectClass Friends.java:

import java.io.Serializable;

public class Friends implements Serializable {
private String friendName;
private String friendId;
private double distanceFromCurrentLocation;

public Friends(String name, String id)
{
    this.friendName = name;
    this.friendId = id;
    this.distanceFromCurrentLocation = getDistanceFromCurrentLocation();

}

public String getFriendName(){
    return friendName;
}

public void setFriendName(String name){
    this.friendName = name;
}

public void setFriendId(String id){
    this.friendId = id;
}
public String getFriendId(){
    return friendId;
}

public double getDistanceFromCurrentLocation(){
    return 0.0;
}

public int hashCode(){
    return friendName.hashCode()*friendId.hashCode();
}

public boolean equals(Object o){
    if(o == null) {
        return false;
    }
    if(!(o instanceof Friends)) {
        return false;
    }

    Friends other = (Friends) o;
    return this.friendId == other.friendId; //friendId is a unique value
   }
}