Implemented queue in java

Author: PaddyKe

contents/stacks_and_queues/code/java/Queue.java

@@ -0,0 +1,71 @@
+import java.util.List;
+import java.util.ArrayList;
+
+public class QueueTest {
+    
+    public static void main(String[] args) {
+	IQueue<Integer> intQueue = new Queue<>();
+
+	intQueue.enqueue(4);
+	intQueue.enqueue(5);
+	intQueue.enqueue(9);
+	
+	System.out.println(intQueue.dequeue());
+	System.out.println(intQueue.size());
+	System.out.println(intQueue.peek());
+    }
+
+}
+
+
+interface IQueue<T> {
+
+   /*
+    * 'dequeue' removes the first element from the queue and returns it
+    */
+    T dequeue();
+
+   /*
+    * 'enqueue' adds an element at the end of the queue and returns the new size
+    */
+    int enqueue(T element);
+    
+
+   /*
+    * 'size' returns the size of the queue
+    */
+    int size();
+
+   /*
+    * 'peek' returns the first element of the queue without removing it
+    */
+    T peek();
+}
+
+
+public class Queue<T> implements  IQueue<T> {
+
+    private List<T> list;
+
+    public Queue() {
+	this.list = new ArrayList();
+    }
+
+    public T dequeue() {
+	return this.list.remove(0);
+    }
+
+    public int enqueue(T element) {
+	this.list.add(element);
+	return this.size();
+    }
+
+    public int size() {
+	return this.list.size();
+    }
+
+    public T peek() {
+	return this.list.get(0);
+    }
+
+}