{"id":1261,"date":"2022-02-26T07:05:25","date_gmt":"2022-02-26T07:05:25","guid":{"rendered":"https:\/\/mdr.foobrdigital.com\/?p=1261"},"modified":"2022-02-26T07:05:25","modified_gmt":"2022-02-26T07:05:25","slug":"queue-interface","status":"publish","type":"post","link":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/2022\/02\/26\/queue-interface\/","title":{"rendered":"Queue Interface"},"content":{"rendered":"\n

In this tutorial, we will learn about the Java Queue interface and its methods.<\/p>\n\n\n\n

The Queue<\/code> interface of the Java collections framework provides the functionality of the queue data structure. It extends the Collection<\/code> interface.<\/p>\n\n\n\n

\n\n\n\n

Classes that Implement Queue<\/h2>\n\n\n\n

Since the Queue<\/code> is an interface, we cannot provide the direct implementation of it.<\/p>\n\n\n\n

In order to use the functionalities of Queue<\/code>, we need to use classes that implement it:<\/p>\n\n\n\n

  • ArrayDeque<\/li>
  • LinkedList<\/li>
  • PriorityQueue<\/li><\/ul>\n\n\n\n
    \"ArrayDeque,<\/figure>\n\n\n\n
    \n\n\n\n

    Interfaces that extend Queue<\/h2>\n\n\n\n

    The Queue<\/code> interface is also extended by various subinterfaces:<\/p>\n\n\n\n

    • Deque<\/code><\/li>
    • BlockingQueue<\/code><\/li>
    • BlockingDeque<\/code><\/li><\/ul>\n\n\n\n
      \"Deque,<\/figure>\n\n\n\n
      \n\n\n\n

      Working of Queue Data Structure<\/h2>\n\n\n\n

      In queues, elements are stored and accessed in First In, First Out<\/strong> manner. That is, elements are added from the behind<\/strong> and removed from the front<\/strong>.<\/p>\n\n\n\n

      \"Working<\/figure>\n\n\n\n
      \n\n\n\n

      How to use Queue?<\/h2>\n\n\n\n

      In Java, we must import java.util.Queue<\/code> package in order to use Queue<\/code>.<\/p>\n\n\n\n

      \/\/ LinkedList implementation of Queue\nQueue<String> animal1 = new LinkedList<>();\n\n\/\/ Array implementation of Queue\nQueue<String> animal2 = new ArrayDeque<>();\n\n\/\/ Priority Queue implementation of Queue\nQueue<String> animal 3 = new PriorityQueue<>();\n<\/code><\/pre>\n\n\n\n
      Here, we have created objects animal1<\/var>, animal2<\/var> and animal3<\/var> of classes LinkedList<\/code>, ArrayDeque<\/code> and PriorityQueue<\/code> respectively. These objects can use the functionalities of the Queue<\/code> interface.<\/p>\n\n\n\n
      \n\n\n\n
      Methods of Queue<\/h2>\n\n\n\n
      The Queue<\/code> interface includes all the methods of the Collection<\/code> interface. It is because Collection<\/code> is the super interface of Queue<\/code>.<\/p>\n\n\n\n
      Some of the commonly used methods of the Queue<\/code> interface are:<\/p>\n\n\n\n
      • add()<\/strong> – Inserts the specified element into the queue. If the task is successful, add()<\/code> returns true<\/code>, if not it throws an exception.<\/li>
      • offer()<\/strong> – Inserts the specified element into the queue. If the task is successful, offer()<\/code> returns true<\/code>, if not it returns false<\/code>.<\/li>
      • element()<\/strong> – Returns the head of the queue. Throws an exception if the queue is empty.<\/li>
      • peek()<\/strong> – Returns the head of the queue. Returns null<\/code> if the queue is empty.<\/li>
      • remove()<\/strong> – Returns and removes the head of the queue. Throws an exception if the queue is empty.<\/li>
      • poll()<\/strong> – Returns and removes the head of the queue. Returns null<\/code> if the queue is empty.<\/li><\/ul>\n\n\n\n
        Implementation of the Queue Interface<\/h2>\n\n\n\n
        1. Implementing the LinkedList Class<\/strong><\/p>\n\n\n\n
        import java.util.Queue;\nimport java.util.LinkedList;\n\nclass Main {\n\n    public static void main(String[] args) {\n        \/\/ Creating Queue using the LinkedList class\n        Queue<Integer> numbers = new LinkedList<>();\n\n        \/\/ offer elements to the Queue\n        numbers.offer(1);\n        numbers.offer(2);\n        numbers.offer(3);\n        System.out.println(\"Queue: \" + numbers);\n\n        \/\/ Access elements of the Queue\n        int accessedNumber = numbers.peek();\n        System.out.println(\"Accessed Element: \" + accessedNumber);\n\n        \/\/ Remove elements from the Queue\n        int removedNumber = numbers.poll();\n        System.out.println(\"Removed Element: \" + removedNumber);\n\n        System.out.println(\"Updated Queue: \" + numbers);\n    }\n}\n<\/code><\/pre>\n\n\n\n
        Output<\/strong><\/p>\n\n\n\n
        Queue: [1, 2, 3]\nAccessed Element: 1\nRemoved Element: 1\nUpdated Queue: [2, 3]\n<\/samp><\/code><\/pre>\n\n\n\n
        <\/p>\n\n\n\n
        2. Implementing the PriorityQueue Class<\/strong><\/p>\n\n\n\n
        import java.util.Queue;\nimport java.util.PriorityQueue;\n\nclass Main {\n\n    public static void main(String[] args) {\n        \/\/ Creating Queue using the PriorityQueue class\n        Queue<Integer> numbers = new PriorityQueue<>();\n\n        \/\/ offer elements to the Queue\n        numbers.offer(5);\n        numbers.offer(1);\n        numbers.offer(2);\n        System.out.println(\"Queue: \" + numbers);\n\n        \/\/ Access elements of the Queue\n        int accessedNumber = numbers.peek();\n        System.out.println(\"Accessed Element: \" + accessedNumber);\n\n        \/\/ Remove elements from the Queue\n        int removedNumber = numbers.poll();\n        System.out.println(\"Removed Element: \" + removedNumber);\n\n        System.out.println(\"Updated Queue: \" + numbers);\n    }\n}\n<\/code><\/pre>\n\n\n\n
        Output<\/strong><\/p>\n\n\n\n
        Queue: [1, 5, 2]\nAccessed Element: 1\nRemoved Element: 1\nUpdated Queue: [2, 5]<\/samp><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
        In this tutorial, we will learn about the Java Queue interface and its methods. The Queue interface of the Java collections framework provides the functionality of the queue data structure. It extends the Collection interface. Classes that Implement Queue Since the Queue is an interface, we cannot provide the direct implementation of it. In order to use the functionalities of Queue, we […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[291],"tags":[],"_links":{"self":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1261"}],"collection":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/comments?post=1261"}],"version-history":[{"count":0,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1261\/revisions"}],"wp:attachment":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/media?parent=1261"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/categories?post=1261"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/tags?post=1261"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}