How can I create an equals method to compare two objects in an array?

Question

How I can compare each object in an array to identify if they are the same; ex. compare a hockey player to a golfer and output they are not the same, or compare two hockey players to each other and output that they are the same.

I am unsure how to implement this.

players[0] = new BaseballPlayer(...stuff);
players[1] = new FootBall(...stuff);
players[2] = new HockeyPlayer(...stuff);
players[3] = new Golfer(...stuff);
players[4] = new BaseballPlayer(...stuff);
players[5] = new FootBall(...stuff);
players[6] = new HockeyPlayer(...stuff);
players[7] = new Golfer(...stuff);
players[8] = new BaseballPlayer(...stuff);
players[9] = new FootBall(...stuff);
players[10] = new HockeyPlayer(...stuff);
players[11] = new Golfer(...stuff);
players[12] = new BaseballPlayer(...stuff);
players[13] = new FootBall(...stuff);
players[14] = new HockeyPlayer(...stuff);
players[15] = new Golfer(...stuff);

Implement a `Comparator` for the class you want to compare, and then use it in `Arrays.sort(...)`. — deHaar, Nov 20 '17 at 20:18
You need to implement `equals()` in each class (or in a shared superclass, which is easier). — Kayaman, Nov 20 '17 at 20:21

jon5477 · Answer 1 · 2017-11-20T20:18:31.200

0

Utilities to implement this have already been provided in the JDK. Please look at Arrays documentation, specifically deepEquals for verifying nested arrays.

edited Nov 20 '17 at 20:18

answered Nov 20 '17 at 20:16

jon5477

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`Arrays.equals()` (and `deepEquals()`) still requires the objects in the array to have `equals()` implemented correctly. Also, you misunderstand the question. It has nothing to do with arrays being equal. – Kayaman Nov 20 '17 at 20:18

score 0 · Answer 2 · answered Nov 20 '17 at 20:22

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See Arrays.equals(Object[], Object[]) and implement equals() (and hashCode()) on your base class (I'm assuming all players inherit from the same Player class).

answered Nov 20 '17 at 20:22

Matthieu

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so lets say: public static boolean equals(players[], players[]) { if (true) { System.out.println("related"); } else System.out.println("not related"); } – Jake Nov 20 '17 at 20:26
^ does not compile not sure how to fix it. – Jake Nov 20 '17 at 20:27
@Jack, either hand-code the static method, or override `equals()` and `hashCode()` inside each class definition (or base-class, whichever makes more sense). – Matthieu Nov 20 '17 at 20:29
As for compile problems, well, just read what the compiler says ;) (try to name your parameters?) – Matthieu Nov 20 '17 at 20:31

How can I create an equals method to compare two objects in an array?

2 Answers2