CODEWITHSUNDEEP
javastackqueue
user3251142
user3251142

Reputation: 175

Method to modify content of a queue by having it reversed, using only a stack and standard API classes?

Ok, so I'm trying to modify a queue to have its content reversed using a stack. I'm a bit lost. I know it shouldn't take much code to write it so I'm hoping someone can help and make this a bit more clear. The inputted queue is random, I'm just using [1,2,3,4] to visualize.

The methods I can use are here:
http://docs.oracle.com/javase/7/docs/api/java/util/Queue.html
http://docs.oracle.com/javase/7/docs/api/java/util/Stack.html

Thanks.

Just from writing this I am getting an error at stack.push(queue) which is
The method push(java.lang.Integer) in the type java.util.Stack<java.lang.Integer> is not applicable for the arguments (java.util.Queue)

  public static void main(String[] args) {
    Queue<Integer> q = new LinkedList<Integer>();
    q.add(1);
    q.add(2);
    q.add(3);
    q.add(4);
    ReverseQueue(q);
  }

  public static void ReverseQueue(Queue queue) {
    Stack<Integer> stack = new Stack<Integer>();
    stack.push(queue);
    System.out.println(queue);
  }

Upvotes: 0

Views: 186

Answers (1)

ethanfar
ethanfar

Reputation: 3778

  public static void main(String[] args) {
    Queue<Integer> q = new LinkedList<Integer>();
    q.add(1);
    q.add(2);
    q.add(3);
    q.add(4);
    reverseQueue(q);
  }

  public static void reverseQueue(Queue<Integer> queue) {
    Stack<Integer> stack = new Stack<Integer>();
    while (!queue.isEmpty()) {
        stack.push(queue.remove());
    }
    while (!stack.isEmpty()) {
        queue.add(stack.pop());
    }
    System.out.println(queue);
  }

Upvotes: 1

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