package hashCodeEquals;

import java.util.HashMap;

import java.util.Map;

/**

* hashCode() Contract : 1. internal consistency: the value of hashCode() may

* only change if a property that is in equals() changes

* 2. equals consistency:

* objects that are equal to each other must return the same hashCode

* 3.collisions: unequal objects may have the same hashCode

**/

public class HashCodeContractMain {

public static void main(String[] args) {

Map<Team, String> leaders = new HashMap<>();

Team team = new Team("New York", "development");

Team team2 = new Team("Boston", "development");

Team team3 = new Team("Boston", "marketing");

leaders.put(team, "Anne");

leaders.put(team2, "Brian");

leaders.put(team3, "Charlie");

Team myTeam = new Team("New York", "development");

System.out.println(team);

System.out.println(team2);

System.out.println(team3);

System.out.println(myTeam);

String myTeamLeader = leaders.get(myTeam);

System.out.println("Result expected Anne :" + myTeamLeader);

// We need to : Equal objects return the same hashCode.

System.out.println("***************************************");

/**

* we want to use instances of the Team class as HashMap keys, we have to

* override the hashCode() method

*/

Map<Team2, String> leaders2 = new HashMap<>();

Team2 team4 = new Team2("New York", "development");

Team2 team5 = new Team2("Boston", "development");

Team2 team6 = new Team2("Boston", "marketing");

leaders2.put(team4, "Anne");

leaders2.put(team5, "Brian");

leaders2.put(team6, "Charlie");

Team2 myTeam2 = new Team2("New York", "development");

System.out.println(team4);

System.out.println(team5);

System.out.println(team6);

System.out.println(myTeam2);

String myTeamLeader2 = leaders2.get(myTeam2);

System.out.println("Result expected Anne :" + myTeamLeader2);

}

}