Return object from arraylist with highest value?

Question

I'm trying to return an object from an arraylist I have, which contains different opponents for my text-based fighting game. The opponents in the arraylist have different "deadlylevels", to seperate one easy opponent from a tough one.

To explain it differently; Let's say I have three opponents in my arraylist, and they have the deadlylevels of 30, 40 and 50, respectively. I want to return the most deadliest of them, so that would be the opponent who has a deadlylevel of 50.

I have already given them different deadlylevels, but I'm not sure how to return the opponent that has the highest deadlylevel.

Sort the List with a Comparator that uses the "deadlylevel" as criterion and get the first (or last) element. — Mick Mnemonic
– Mick Mnemonic, Commented Apr 16, 2015 at 23:05
Paul's answer will do exactly what I suggested, but with less code, so you should probably choose that solution. — Mick Mnemonic
– Mick Mnemonic, Commented Apr 16, 2015 at 23:43

Donald Raab · Accepted Answer · 2017-02-13 20:39:02Z

If you wanted the maximum level, that would just be max(). But you want the max opponent, by level. In Eclipse Collections, we call that pattern maxBy(). If you can replace your ArrayList with MutableList then it becomes:

MutableList<Opponent> opponents = ...;
Opponent opponent = opponents.maxBy(Opponent::getDeadlyLevel);

If you can't or won't convert the ArrayList, you can still use static utility on Iterate.

Opponent opponent = Iterate.maxBy(opponents, Opponent::getDeadlyLevel);

You could use Collections.max() along with Comparator.comparing() to build the Comparator.

Opponent opponent =
    Collections.max(opponents, Comparator.comparing(Opponent::getDeadlyLevel));

Or you could use Java 8 Streams.

Optional<Opponent> optionalOpponent = 
    opponents.stream().max(Comparator.comparing(Opponent::getDeadlyLevel));
Opponent opponent = optionalOpponent.get(); // If you're sure there's at least one

Note: I am a committer for Eclipse Collections.

user4668606 · Accepted Answer · 2015-04-16 23:06:16Z

4

Create a Comparator that compares the levels of the oponents and use Collections.max(oponentList , theComparator).

answered Apr 16, 2015 at 23:06

user4668606

Comments

Bohemian · Accepted Answer · 2015-04-17 04:03:46Z

3

Use Stream#max() providing a function for the relevant attribute:

List<Fighter> list; // given a list of Fighters
Fighter deadliest = list.stream()
    .max((a,b) -> a.getDeadlyLevel() - b.getDeadlyLevel())
    .get();

edited Apr 17, 2015 at 4:03

answered Apr 16, 2015 at 23:11

Bohemian♦

427k103 gold badges603 silver badges750 bronze badges

2 Comments

Craig P. Motlin Over a year ago

The example doesn't compile.

Bohemian Over a year ago

@CraigP.Motlin oops - thumbing code on train (coded a Function not a BiFunction). Fixed now - thx.

zawhtut · Accepted Answer · 2015-04-17 08:33:31Z

1

Use Comparator.comparing

import java.util.Arrays;
import java.util.Comparator;
import java.util.List;


public class DeathMatch {
    public static void main(String[] arg){
        List<Opponent> list = Arrays.asList(new Opponent("ZZ",10),new Opponent("WW",50),new Opponent("MM", 30));
        Opponent deadliest = list.stream().max(Comparator.comparing(p->p.getLevel())).get();
        System.out.println(deadliest.getName()+","+ deadliest.getLevel());
    }
}

answered Apr 17, 2015 at 8:33

zawhtut

8,6015 gold badges55 silver badges78 bronze badges

Collectives™ on Stack Overflow

Return object from arraylist with highest value?

4 Answers 4

Comments

Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related