| 9. 16. 1. The Collections Framework New Types |
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New types in Collections Framework |
- Deque
- BlockingDeque
- NavigableMap
- NavigableSet
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The Deque Interface |
Deque [pronounced "deck"] is short for double-ended queue. |
java.util.Deque is a subinterface of Queue. |
A deque is a queue that supports element insertion and removal at both ends. |
You can also restrict the maximum number of elements in a Deque. |
Deque can also be used as a stack. |
Methods are available for adding, removing, and inspecting elements. |
The ArrayDeque class is an implementation of Deque that does not impose capacity restriction. |
ArrayDeque always grows as necessary to support new elements. |
Using Deque as a stack |
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import java.util.ArrayDeque;
import java.util.Deque;
public class IntegerStack {
private Deque<Integer> data = new ArrayDeque<Integer>();
public void push(Integer element) {
data.addFirst(element);
}
public Integer pop() {
return data.removeFirst();
}
public Integer peek() {
return data.peekFirst();
}
public String toString() {
return data.toString();
}
public static void main(String[] args) {
IntegerStack stack = new IntegerStack();
for (int i = 0; i < 5; i++) {
stack.push(i);
}
System.out.println("After pushing 5 elements: " + stack);
int m = stack.pop();
System.out.println("Popped element = " + m);
System.out.println("After popping 1 element : " + stack);
int n = stack.peek();
System.out.println("Peeked element = " + n);
System.out.println("After peeking 1 element : " + stack);
}
}
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After pushing 5 elements: [4, 3, 2, 1, 0]
Popped element = 4
After popping 1 element : [3, 2, 1, 0]
Peeked element = 3
After peeking 1 element : [3, 2, 1, 0] |