Java--Using the Deque Interface

1.working with the ArrayDeque Class

package self;

import java.util.ArrayDeque;

//import java.util.Hashtable;

public class ArrayDequeDemo {
    public static void main(String args[]) {
        ArrayDeque<Double> obj = new ArrayDeque<Double>();
        Double dobj1 = new Double(7.5);
        Double dobj2 = new Double(8.5);
        Double dobj3 = new Double(9.5);
        Double dobj4 = new Double(10.5);

        System.out.println("Size of ArrayDeque is :" + obj.size());

        obj.add(dobj1);
        obj.add(dobj2);

        System.out.println("\nArrayDeque after adding the objects：" + obj);
        System.out.println("Size of ArrayDeque after adding objects " + obj.size());

        obj.addFirst(dobj3);
        obj.addFirst(dobj4);

        System.out.println("ArrayDeque after adding the objects at first and last  " + obj);
        System.out.println("Size of ArrayDeque after adding objects at first and last " + obj.size());

        obj.removeFirst();
        System.out.println("\nArrayDeque after removing the first object:" + obj);
        System.out.println("Size of ArrayDeque after removing the first objects " + obj.size());

    }
}

测试结果：