Java Utility Library

Java TreeSet - first() Method

The java.util.TreeSet.first() method returns the first (lowest) element currently in this set.

Syntax

public E first()

Here, E is the type of element maintained by the container.

Parameters

No parameter is required.

Return Value

Returns the first (lowest) element currently in this set.

Exception

Throws NoSuchElementException, if this set is empty.

Example:

In the example below, the java.util.TreeSet.first() method is used to get the value of first (lowest) element of the treeset.

import java.util.*;

public class MyClass {
  public static void main(String[] args) {
    //creating a treeset
    TreeSet<Integer> MySet = new TreeSet<Integer>();

    //populating the set
    MySet.add(40);
    MySet.add(20);
    MySet.add(10);
    MySet.add(30);

    //printing the set
    System.out.println("MySet contains: " + MySet); 

    //printing the first element
    System.out.println("First Element of the Set: " + MySet.first());
  }
}

The output of the above code will be:

MySet contains: [10, 20, 30, 40]
First Element of the Set: 10

❮ Java.util - TreeSet