In order to sort first by ID and if the Id’s are same then sort by name. Please follow the code

Example

package collections;

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

class Student implements Comparable<Student> {
	int ID;
	String name;
	char grade;

	public Student(int iD, String name, char grade) {
		super();
		ID = iD;
		this.name = name;
		this.grade = grade;
	}

	@Override
	public String toString() {
		return "Student [ID=" + ID + ", name=" + name + ", grade=" + grade + "]";
	}

	@Override
	public int compareTo(Student o) {
		int result = this.ID - o.ID; // Sorting by ID

		if (result == 0) { // if both the integer values are same, then sort by name
			result = this.name.compareTo(o.name); // comparing strings
		}

		return result;
	}
}

public class StudentSort {

	public static void main(String[] args) {

		List<Student> stu = new ArrayList<>();
		stu.add(new Student(10, "General Motors", 'A'));
		stu.add(new Student(100, "Ferrari", 'B'));
		stu.add(new Student(5, "Mustang", 'C'));
		stu.add(new Student(5, "Ford", 'F'));

		System.out.println("Before");
		printCollections(stu);
		Collections.sort(stu);
		System.out.println("After");
		printCollections(stu);
	}

	private static void printCollections(List<Student> stu) {
		for (Student s : stu)
			System.out.println(s);
	}
}

Output

Before
Student [ID=10, name=General Motors, grade=A]
Student [ID=100, name=Ferrari, grade=B]
Student [ID=5, name=Mustang, grade=C]
Student [ID=5, name=Ford, grade=F]
After
Student [ID=5, name=Ford, grade=F]
Student [ID=5, name=Mustang, grade=C]
Student [ID=10, name=General Motors, grade=A]
Student [ID=100, name=Ferrari, grade=B]