Classes in Java implement the comparable interface for sorting

Import Java.util.Arrays;

public class Sortapp {
public static void Main (string[] args) {
student[] Stus = new Student[3];
Stus[0] = new Student (11, 99);
STUS[1] = new Student (13, 92);
STUS[2] = new Student (13, 89);
Arrays.sort (Stus);
for (Student student:stus) {
System.out.println ("age=" + student.getage () + ";" + "score="
+ Student.getscore ());
}
}

Static Class Student implements Comparable<student> {
private int age;
private int score;

Public Student () {
}

Public Student (int age, int score) {
This.age = age;
This.score = score;
}

public int Getscore () {
return score;
}

public void SetScore (int score) {
This.score = score;
}

public int getage () {
return age;
}

public void Setage (int.) {
This.age = age;
}

public int compareTo (Student o) {
int result = this.age-o.age;//O indicates that the object to be compared will be sorted in descending order when the result is in ascending order as negative
if (Result! = 0) {
return result;
} else {
Return this.score-o.score;//If result=0 compares the second column
}
}

}
}

In the example above we sort the row as a key in Hadoop, because the default sort for Hadoop is only for key,value, and if you want to sort the value, we need to customize the collation to use KeyValue as key

Classes in Java implement the comparable interface for sorting