07 Compare

Collections.sort(list); // sort() is an abstract function

Collections.sort( list, new NameComparator() );

// Comparable
class Student implements Comparable<Student>
{
  String name;
  int age;

  Student(String n, int a)
  {
    name = n;
    a = age
  }

  public int compareTo(Student s)
  {
    if(age < s.age)
      return -1;
    else if(age > s.age)
      return 1;
    else
      return 0;
  }
}

// ArrayList

Collections.sort(al); // sorting based on age
//display

// Comparable
class Student implements Comparable<Student>
{
  String name;
  int age;

  Student(String n, int a)
  {
    name = n;
    a = age
  }
}

class AgeComparator implements Comparator<Student>
{
  public int compare(Student s1, Student s2)
    {
    if(s1.age < s2.age)
      return -1;
    else if(s1.age > s2.age)
      return 1;
    else
      return 0;
    }
}

class NameComparator implements Comparator<Student>
{
  public void compare(Student s1, Student s2)
  {
    return s1.name.compareTo(s2.name);
  }
}

// ArrayList

Collections.sort(al, new AgeComparator());
// display

Collections.sort(al, new NameComparator());
// display