java : Saya sedang mengikuti tes masuk kerja, dan soalnya adalah program dibawah ini :

import java.util.List;

import java.util.ArrayList;



public class Test {

 public static void main(String... args) throws Exception {

 Deque queue = new Deque();



 int random = (int)(Math.random() * 100);



 queue.addLast(10);

 queue.addLast(20);

 queue.addLast(random);

 queue.addLast(40);

 queue.addLast(50);

 

 for(int i = 0; i < 2; i++) {

 assertTrue(get(queue, 0) == 10);

 assertTrue(get(queue, 1) == 20);

 assertTrue(get(queue, 2) == random);

 assertTrue(get(queue, 3) == 40);

 assertTrue(get(queue, 4) == 50);



 try {

 get(queue, 5);

 assertTrue(false);

 } catch(Exception e) {

 assertTrue(true);

 }

 }

 }



 public static void assertTrue(boolean v) {

 if(!v) {

 Thread.dumpStack();

 System.exit(0);

 }

 }



 public static int get(Deque queue, int index) throws Exception {

 // 1) Only fill in your code in this method

 // 2) Do not modify anything else

 // 3) Use of 'new' keyword is not allowed

 // 4) Do not use reflection

 // 5) Do not use string concatenation

 // 6) If your code cannot compile or fails the test case in 'main()', you will NOT receive a response from us

 }

}



class Deque {

 private List<Integer> items;



 public Deque() {

 items = new ArrayList<Integer>();

 }



 public void addFirst(int item) {

 items.add(0, item);

 }



 public void addLast(int item) {

 items.add(item);

 }



 public int removeFirst() {

 if(isEmpty()) throw new RuntimeException();

 return items.remove(0);

 }



 public int removeLast() {

 if(isEmpty()) throw new RuntimeException();

 return items.remove(items.size() - 1);

 }



 public boolean isEmpty() {

 return items.size() == 0;

 }

}

Pertanyaan saya adalah :
1. Setelah baca soalnya, keluaran apa yang diinginkan dari soal tersebut ?
2. Apa saja yang harus saya pelajari supaya bisa menjawab soal tersebut ?