{"id":1265,"date":"2022-02-26T07:09:14","date_gmt":"2022-02-26T07:09:14","guid":{"rendered":"https:\/\/mdr.foobrdigital.com\/?p=1265"},"modified":"2022-02-26T07:09:14","modified_gmt":"2022-02-26T07:09:14","slug":"deque-interface","status":"publish","type":"post","link":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/2022\/02\/26\/deque-interface\/","title":{"rendered":"Deque Interface"},"content":{"rendered":"\n

In this tutorial, we will learn about the Deque interface, how to use it, and its methods.<\/p>\n\n\n\n

The Deque<\/code> interface of the Java collections framework provides the functionality of a double-ended queue. It extends the Queue<\/code> interface.<\/p>\n\n\n\n

\n\n\n\n

Working of Deque<\/h2>\n\n\n\n

In a regular queue, elements are added from the rear and removed from the front. However, in a deque, we can insert and remove elements from both front and rear<\/strong>.<\/p>\n\n\n\n

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

Classes that implement Deque<\/h2>\n\n\n\n

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

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

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

    In Java, we must import the java.util.Deque<\/code> package to use Deque<\/code>.<\/p>\n\n\n\n

    \/\/ Array implementation of Deque\nDeque<String> animal1 = new ArrayDeque<>();\n\n\/\/ LinkedList implementation of Deque\nDeque<String> animal2 = new LinkedList<>();\n<\/code><\/pre>\n\n\n\n
    Here, we have created objects animal1<\/var> and animal2<\/var> of classes ArrayDeque<\/var> and LinkedList<\/var>, respectively. These objects can use the functionalities of the Deque<\/code> interface.<\/p>\n\n\n\n
    \n\n\n\n
    Methods of Deque<\/h2>\n\n\n\n
    Since\u00a0Deque<\/code>\u00a0extends the\u00a0Queue<\/code>\u00a0interface, it inherits all the methods of\u00a0the Queue interface.<\/p>\n\n\n\n
    Besides methods available in the Queue<\/code> interface, the Deque<\/code> interface also includes the following methods:<\/p>\n\n\n\n
    • addFirst()<\/strong> – Adds the specified element at the beginning of the deque. Throws an exception if the deque is full.<\/li>
    • addLast()<\/strong> – Adds the specified element at the end of the deque. Throws an exception if the deque is full.<\/li>
    • offerFirst()<\/strong> – Adds the specified element at the beginning of the deque. Returns false<\/code> if the deque is full.<\/li>
    • offerLast()<\/strong> – Adds the specified element at the end of the deque. Returns false<\/code> if the deque is full.<\/li>
    • getFirst()<\/strong> – Returns the first element of the deque. Throws an exception if the deque is empty.<\/li>
    • getLast()<\/strong> – Returns the last element of the deque. Throws an exception if the deque is empty.<\/li>
    • peekFirst()<\/strong> – Returns the first element of the deque. Returns null<\/code> if the deque is empty.<\/li>
    • peekLast()<\/strong> – Returns the last element of the deque. Returns null<\/code> if the deque is empty.<\/li>
    • removeFirst()<\/strong> – Returns and removes the first element of the deque. Throws an exception if the deque is empty.<\/li>
    • removeLast()<\/strong> – Returns and removes the last element of the deque. Throws an exception if the deque is empty.<\/li>
    • pollFirst()<\/strong> – Returns and removes the first element of the deque. Returns null<\/code> if the deque is empty.<\/li>
    • pollLast()<\/strong> – Returns and removes the last element of the deque. Returns null<\/code> if the deque is empty.<\/li><\/ul>\n\n\n\n
      \n\n\n\n
      Deque as Stack Data Structure<\/h2>\n\n\n\n
      The Stack<\/code> class of the Java Collections<\/code> framework provides the implementation of the stack.<\/p>\n\n\n\n
      However, it is recommended to use\u00a0Deque<\/code>\u00a0as a stack instead of\u00a0the Stack class. It is because methods of\u00a0Stack<\/code>\u00a0are synchronized.<\/p>\n\n\n\n
      Here are the methods the Deque<\/code> interface provides to implement stack:<\/p>\n\n\n\n
      • push()<\/code> – adds an element at the beginning of deque<\/li>
      • pop()<\/code> – removes an element from the beginning of deque<\/li>
      • peek()<\/code> – returns an element from the beginning of deque<\/li><\/ul>\n\n\n\n
        \n\n\n\n
        Implementation of Deque in ArrayDeque Class<\/h2>\n\n\n\n
        import java.util.Deque;\nimport java.util.ArrayDeque;\n\nclass Main {\n\n    public static void main(String[] args) {\n        \/\/ Creating Deque using the ArrayDeque class\n        Deque<Integer> numbers = new ArrayDeque<>();\n\n        \/\/ add elements to the Deque\n        numbers.offer(1);\n        numbers.offerLast(2);\n        numbers.offerFirst(3);\n        System.out.println(\"Deque: \" + numbers);\n\n        \/\/ Access elements of the Deque\n        int firstElement = numbers.peekFirst();\n        System.out.println(\"First Element: \" + firstElement);\n\n        int lastElement = numbers.peekLast();\n        System.out.println(\"Last Element: \" + lastElement);\n\n        \/\/ Remove elements from the Deque\n        int removedNumber1 = numbers.pollFirst();\n        System.out.println(\"Removed First Element: \" + removedNumber1);\n\n        int removedNumber2 = numbers.pollLast();\n        System.out.println(\"Removed Last Element: \" + removedNumber2);\n\n        System.out.println(\"Updated Deque: \" + numbers);\n    }\n}\n<\/code><\/pre>\n\n\n\n
        Output<\/strong><\/p>\n\n\n\n
        Deque: [3, 1, 2]\nFirst Element: 3\nLast Element: 2\nRemoved First Element: 3\nRemoved Last Element: 2\nUpdated Deque: [1]\n<\/samp><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
        In this tutorial, we will learn about the Deque interface, how to use it, and its methods. The Deque interface of the Java collections framework provides the functionality of a double-ended queue. It extends the Queue interface. Working of Deque In a regular queue, elements are added from the rear and removed from the front. However, in a deque, […]<\/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\/1265"}],"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=1265"}],"version-history":[{"count":0,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/posts\/1265\/revisions"}],"wp:attachment":[{"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/media?parent=1265"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/categories?post=1265"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mudassirbackup.infinitycodestudio.com\/index.php\/wp-json\/wp\/v2\/tags?post=1265"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}