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Question: How do you sort by Student name or age ?

We can use Comparable, and the Custom class should extend "Comparable" class and override the compareTo method.

# Comparable

Comparable class has only one method:

a
public int compareTo(){
	return 0 ; // <- return -ve or +ve;
}
public int compareTo(){
	return a - b ; 
// b > a, so if sorted in order ,
// then it will return a negative 
// output : ab

# Sort by custom class

  1. your custom class implement Comparable <YourClass>
  2. override comparaTo(), something like below
a
return - this.getName().compareTo(obj.getName()) ;

3 in the main(), use Collections.sort()`

a
ArrayList<Student> classroom = new ArrayList<>();  
    classroom.add(new Student("Tony", 12));  
    classroom.add(new Student("hanyu", 9));  
    classroom.add(new Student("tiff", 10));  
    classroom.add(new Student("Alice", 6));  
    classroom.add(new Student("Kelly",15));  
  
       Collections.sort(classroom);  
  
    classroom.forEach(student -> {  
        System.out.println(student);  
    });  
}

remember to Override : toString()

public String toString() {  
    return "Student{" +  
            "name='" + name + '\'' +  
            ", age=" + age +  
            '}';