Example of Using TreeSet with User-Defined Objects

The following program demonstrates an Example of Using TreeSet with User-Defined Objects.

Since here we are creating our TreeSet object with the user-defined objects, we must implement the Comparable interface in the class that will serve as the source to create user-defined objects. In this example, we have a class Emp that contains certain attributes along with the getter and setter methods. The Emp class implements the Comparable interface and defines the compareTo() method.

import java.util.Iterator;
import java.util.TreeSet;

public class TreesetEmpDemo {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		TreeSet<Emp> ts=new TreeSet<Emp>();
		ts.add(new Emp(11, "A", 12000));
		ts.add(new Emp(12, "B", 17700));
		ts.add(new Emp(13, "C", 18700));
		ts.add(new Emp(14, "D", 14500));
		ts.add(new Emp(15, "E", 11400));
		ts.add(new Emp(16, "F", 12000));
		ts.add(new Emp(17, "G", 16700));
		
		System.out.println("Elements in TreeSet: ");
		Iterator it=ts.iterator();
		while(it.hasNext())
		{
			System.out.println(it.next().toString());
		}
		
		System.out.println("First Element of the TreeSet: "+ts.first());
		System.out.println("Last Element of the TreeSet: "+ts.last());
	}

}
class Emp implements Comparable<Emp>
{
	int emp_id;
	String ename;
	int salary;
	
	public int compareTo(Emp e2)
	{
		if (salary==e2.getSalary())
			return 0;
		else
			if(salary>e2.getSalary())
				return 1;
			else
				return -1;
	}
	public Emp() {
		super();
	}
	
	public Emp(int emp_id, String ename, int salary) {
		super();
		this.emp_id = emp_id;
		this.ename = ename;
		this.salary = salary;
	}

	public int getEmp_id() {
		return emp_id;
	}
	public void setEmp_id(int emp_id) {
		this.emp_id = emp_id;
	}
	public String getEname() {
		return ename;
	}
	public void setEname(String ename) {
		this.ename = ename;
	}
	public int getSalary() {
		return salary;
	}
	public void setSalary(int salary) {
		this.salary = salary;
	}
	@Override
	public String toString() {
		return "Employee Details: [emp_id=" + emp_id + ", ename=" + ename + ", salary=" + salary + "]";
	}
	
}

Output

**Demonstrating Example of Using TreeSet with User-Defined Objects**

Further Reading