AbstractSet clear() method in Java with Example

Last Updated : 24 Dec, 2018
The clear() method of AbstractSet in Java is used to remove all the elements from a set. The set will be empty after this call returns. Syntax: 
public void clear()
Parameters: This function has no parameters. Returns: The method does not return any value. It removes all the elements in the set and makes it empty. Below examples illustrates the AbstractSet.clear() method: Example 1: Java 
// Java code to demonstrate the working of
// clear() method in AbstractSet

import java.util.*;

public class GFG {
    public static void main(String[] args)
    {
        // creating an AbstractSet
        AbstractSet<Integer> arr
            = new TreeSet<Integer>();

        // using add() to initialize values
        // [1, 2, 3, 4]
        arr.add(1);
        arr.add(2);
        arr.add(3);
        arr.add(4);

        // set initially
        System.out.println("The set initially: "
                           + arr);

        // clear function used
        arr.clear();

        // set after clearing all elements
        System.out.println("The set after "
                           + "using clear() method: "
                           + arr);
    }
}
Output: 
The set initially: [1, 2, 3, 4]
The set after using clear() method: []
Example 2: Java 
// Java code to demonstrate the working of
// clear() method in AbstractSet

import java.util.*;

public class GFG {
    public static void main(String[] args)
    {
        // creating an AbstractSet
        AbstractSet<String> arr
            = new TreeSet<String>();

        // using add() to initialize values
        // [Geeks, For, ForGeeks, GeeksForGeeks]
        arr.add("Geeks");
        arr.add("For");
        arr.add("ForGeeks");
        arr.add("GeeksForGeeks");

        // set initially
        System.out.println("The set initially: "
                           + arr);

        // clear function used
        arr.clear();

        // set after clearing all elements
        System.out.println("The set after "
                           + "using clear() method: "
                           + arr);
    }
}
Output: 
The set initially: [For, ForGeeks, Geeks, GeeksForGeeks]
The set after using clear() method: []
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