Java PriorityQueue clear() method

The clear() method of PriorityQueue class Removes all the elements from this priority queue. After calling this method, the queue will be empty.

Syntax

Parameter

Specified By

The clear() method of class PriorityQueue is specified by clear() method in interface Collection<E>.

Override

The clear() method of class PriorityQueue overrides the clear() method of class AbstractQueue<E>.

Example 1

import java.util.PriorityQueue;

public class JavaPriorityQueueclearMethodExample1 {
public static void main(String[] args) {
PriorityQueue<String> pQueue = new PriorityQueue<String>();
// Adding items to the pQueue using add()

pQueue.add("C");
pQueue.add("C++");
pQueue.add("Java");
pQueue.add("Python");

// Printing the elements

System.out.println("Course : " + pQueue);

//deleting the elements

pQueue.clear();

System.out.println("After clearing the queue : ");
System.out.println(pQueue);

    }
}

Output:

Course : [C, C++, Java, Python]
After clearing the queue :
[]

Example 2

import java.util.PriorityQueue;

class Student extends Object implements Comparable< Student>{
    String rollNo, name,course;
int age;

public Student(String rollNo, String name, String course,int age) {

this.rollNo= rollNo;
this.name = name;
this.course= course;
this.age= age;
    }

@Override

public int compareTo(Student o) {

return 0;
    }
}

public class JavaPriorityQueueclearMethodExample2 {
static int i =1;
public static void main(String[] args) {

PriorityQueue<Student>pQueue = new PriorityQueue<>();

        Student val1 = new Student("2","ravi","C",21);
        Student val2 = new Student("1","Geetanjali","Java",21);
        Student val3 = new Student("3","Himanshu Bhardwaj","C++",21);

pQueue.add(val1);
pQueue.add(val2);
pQueue.add(val3);

for(Student xyz:pQueue){

System.out.println(i++ +" Roll No = "+xyz.rollNo+"\n Name = "+xyz.name +"\n Course = "

+xyz.course+"\n Age = "+xyz.age+"\n");
        }
pQueue.clear();

System.out.println("After clearing the queue :\n "+pQueue);

     }
}         

Output:

1 Roll No = 2
 Name = ravi
 Course = C
 Age = 21

2 Roll No = 1
 Name = Geetanjali
 Course = Java
 Age = 21

3 Roll No = 3
 Name = HimanshuBhardwaj
 Course = C++
 Age = 21

After clearing the queue :
 []

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