Java/DataStructures/Queues/GenericArrayListQueue.java at master · lstarby/Java · GitHub

42 lines (36 loc) · 1.13 KB

import java.util.ArrayList;

public class GenericArrayListQueue<T> {

ArrayList<T> _queue = new ArrayList<T>();

private boolean hasElements() {

return !_queue.isEmpty();

}

public T peek() {

T result = null;

if(this.hasElements()) { result = _queue.get(0); }

return result;

}

public boolean add(T element) {

return _queue.add(element);

}

public T poll() {

T result = null;

if(this.hasElements()) { result = _queue.remove(0); }

return result;

}

public static void main(String[] args) {

GenericArrayListQueue<Integer> queue = new GenericArrayListQueue<Integer>();

System.out.println("Running...");

assert queue.peek() == null;

assert queue.poll() == null;

assert queue.add(1) == true;

assert queue.peek() == 1;

assert queue.add(2) == true;

assert queue.peek() == 1;

assert queue.poll() == 1;

assert queue.peek() == 2;

assert queue.poll() == 2;

assert queue.peek() == null;

assert queue.poll() == null;

System.out.println("Finished.");

}

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