How to implement the Java comparable interface?
You just have to define that Animal implements Comparable<Animal>
i.e. public class Animal implements Comparable<Animal>
. And then you have to implement the compareTo(Animal other)
method that way you like it.
@Override
public int compareTo(Animal other) {
return Integer.compare(this.year_discovered, other.year_discovered);
}
Using this implementation of compareTo
, animals with a higher year_discovered
will get ordered higher. I hope you get the idea of Comparable
and compareTo
with this example.
You need to:
- Add
implements Comparable<Animal>
to the class declaration; and - Implement a
int compareTo( Animal a )
method to perform the comparisons.
Like this:
public class Animal implements Comparable<Animal>{
public String name;
public int year_discovered;
public String population;
public Animal(String name, int year_discovered, String population){
this.name = name;
this.year_discovered = year_discovered;
this.population = population;
}
public String toString(){
String s = "Animal name: "+ name+"\nYear Discovered: "+year_discovered+"\nPopulation: "+population;
return s;
}
@Override
public int compareTo( final Animal o) {
return Integer.compare(this.year_discovered, o.year_discovered);
}
}