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Java ArrayDeque clear() Method
Description
The Java ArrayDeque clear() method removes all of the elements from this deque. This method is very useful when we want to reuse a queue or reset the queue.
Declaration
Following is the declaration for java.util.ArrayDeque.clear() method
public void clear()
Parameters
NA
Return Value
This method does not return any value.
Exception
NA
Clearing an ArrayDeque of Integers Example
The following example shows the usage of Java ArrayDeque clear() method. In this example, we're using Integers. As first step, we're populating the arraydeque object and printing it. Then we're print the size of the arraydeque object and perform clear operation. After clearing, we're printing the size of the arraydeque object which is 0 now.
package com.tutorialspoint; import java.util.ArrayDeque; import java.util.Deque; public class ArrayDequeDemo { public static void main(String[] args) { // create an empty array deque Deque<Integer> deque = new ArrayDeque<>(); // use add() method to add elements in the deque deque.add(20); deque.add(30); deque.add(10); // let us print all the elements available in deque System.out.println("ArrayDeque = " + deque); // finding size of this deque int retval = deque.size(); System.out.println("Deque consists of "+ retval +" elements"); System.out.println("Performing clear operation !!"); deque.clear(); retval = deque.size(); System.out.println("Now, deque consists of "+ retval +" elements"); } }
Output
Let us compile and run the above program, this will produce the following result −
ArrayDeque = [20, 30, 10] Deque consists of 3 elements Performing clear operation !! Now, deque consists of 0 elements
Clearing an ArrayDeque of Strings Example
The following example shows the usage of Java ArrayDeque clear() method. In this example, we're using Strings. As first step, we're populating the arraydeque object and printing it. Then we're print the size of the arraydeque object and perform clear operation. After clearing, we're printing the size of the arraydeque object which is 0 now.
package com.tutorialspoint; import java.util.ArrayDeque; import java.util.Deque; public class ArrayDequeDemo { public static void main(String[] args) { // create an empty array deque Deque<String> deque = new ArrayDeque<>(); // use add() method to add elements in the deque deque.add("A"); deque.add("B"); deque.add("C"); // let us print all the elements available in deque System.out.println("ArrayDeque = " + deque); // finding size of this deque int retval = deque.size(); System.out.println("Deque consists of "+ retval +" elements"); System.out.println("Performing clear operation !!"); deque.clear(); retval = deque.size(); System.out.println("Now, deque consists of "+ retval +" elements"); } }
Output
Let us compile and run the above program, this will produce the following result −
ArrayDeque = [A, B, C] Deque consists of 3 elements Performing clear operation !! Now, deque consists of 0 elements
Clearing an ArrayDeque of Objects Example
The following example shows the usage of Java ArrayDeque clear() method. In this example, we're using Student objects. As first step, we're populating the arraydeque object and printing it. Then we're print the size of the arraydeque object and perform clear operation. After clearing, we're printing the size of the arraydeque object which is 0 now.
package com.tutorialspoint; import java.util.ArrayDeque; import java.util.Deque; public class ArrayDequeDemo { public static void main(String[] args) { // create an empty array deque Deque<Student> deque = new ArrayDeque<>(); // use add() method to add elements in the deque deque.add(new Student(1, "Julie")); deque.add(new Student(2, "Robert")); deque.add(new Student(3, "Adam")); // let us print all the elements available in deque System.out.println("ArrayDeque = " + deque); // finding size of this deque int retval = deque.size(); System.out.println("Deque consists of "+ retval +" elements"); System.out.println("Performing clear operation !!"); deque.clear(); retval = deque.size(); System.out.println("Now, deque consists of "+ retval +" elements"); } } class Student { int rollNo; String name; Student(int rollNo, String name){ this.rollNo = rollNo; this.name = name; } @Override public String toString() { return "[ " + this.rollNo + ", " + this.name + " ]"; } }
Output
Let us compile and run the above program, this will produce the following result −
ArrayDeque = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]] Deque consists of 3 elements Performing clear operation !! Now, deque consists of 0 elements