The clear() method of AbstractQueue removes all of the elements from this queue. The queue will be empty after this call returns.
Syntax:
public void clear()
Parameters: This method does not accept any parameters.
Returns: The method does not returns anything.
Below programs illustrate clear() method:
Program 1:
// Java program to illustrate the// AbstractQueue clear() methodimport java.util.*;import java.util.concurrent.LinkedBlockingQueue;  public class GFG1 {    public static void main(String[] argv)        throws Exception    {        // Creating object of AbstractQueue<Integer>        AbstractQueue<Integer>            AQ1 = new LinkedBlockingQueue<Integer>();          // Populating AQ1        AQ1.add(10);        AQ1.add(20);        AQ1.add(30);        AQ1.add(40);        AQ1.add(50);          // print AQ        System.out.println("AbstractQueue1 contains : " + AQ1);          AQ1.clear();        System.out.println("AbstractQueue1 : " + AQ1);    }} |
Output:
AbstractQueue1 contains : [10, 20, 30, 40, 50] AbstractQueue1 : []
Program 2:
// Java program to illustrate the// AbstractQueue clear() methodimport java.util.*;import java.util.concurrent.LinkedBlockingQueue;  public class GFG1 {    public static void main(String[] argv)        throws Exception    {        // Creating object of AbstractQueue<String>        AbstractQueue<String>            AQ1 = new LinkedBlockingQueue<String>();          // Populating AQ1        AQ1.add("gopal");        AQ1.add("gfg");        AQ1.add("java");          // print AQ        System.out.println("AbstractQueue1 contains : " + AQ1);          AQ1.clear();        System.out.println("AbstractQueue1 : " + AQ1);    }} |
Output:
AbstractQueue1 contains : [gopal, gfg, java] AbstractQueue1 : []
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/AbstractQueue.html#clear–
