Java multiple way sorting - Comparator example .

Compare multiple fields using Comparator:

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

class SortByAnimalByName implements Comparator<Animal> {

@Override
public int compare(Animal o1, Animal o2) {
return o1.name.compareTo(o2.name);
}

}

class SortByAnimalByColor implements Comparator<Animal> {

@Override
public int compare(Animal o1, Animal o2) {
return o1.color.compareTo(o2.color);
}

}

class SortByAnimalByWeight implements Comparator<Animal> {

@Override
public int compare(Animal o1, Animal o2) {
if (o1.weight > o2.weight) {
return 1;
}
if (o1.weight < o2.weight) {
return -1;
}
return 0;
}

}

class SortByAllAnimal implements Comparator<Animal> {
List<Comparator<Animal>> com;

SortByAllAnimal(Comparator<Animal>... all) {
this.com = Arrays.asList(all);

}

@Override
public int compare(Animal o1, Animal o2) {
for (Comparator<Animal> x : com) {
int res = x.compare(o1, o2);
if (res != 0) {
return res;
}
}
return 0;
}

}

class Animal {
String color;
String name;
int weight;

Animal(String c, String n, int w) {
this.color = c;
this.name = n;
this.weight = w;

}

public String toString() {
return this.color + " " + this.name + " " + this.weight;
}
}

public class ComparatorMultipleData {
public static void main(String[] args) {
List<Animal> l = new ArrayList();
Animal a1 = new Animal("black", "dog", 20);
Animal a2 = new Animal("white", "cat", 15);
Animal a3 = new Animal("black", "elephant", 120);
Animal a4 = new Animal("white", "horse", 80);
l.add(a1);
l.add(a2);
l.add(a3);
l.add(a4);
System.out.println(l);
Collections.sort(l,
new SortByAllAnimal(new SortByAnimalByName(), new SortByAnimalByColor()));

System.out.println(l);
}

}

---

Output:

[black dog 20, white cat 15, black elephant 120, white horse 80] 
[white cat 15, black dog 20, black elephant 120, white horse 80]