Question

In Java, you can iterate an ArrayList in different ways. Write the following methods to print Integers in an ArrayList iterating in different ways:

1. // Using basic while / for loop
void printArrayListBasicLoop(ArrayList<Integer> al);

2. // Using enhanced for loop (:)
void printArrayListEnhancedLoop(ArrayList<Integer> al);

3. // Using basic for loop with iterator
void printArrayListForLoopListIterator(ArrayList<Integer> al);

4. // Using basic while loop with iterator

void printArrayListWhileLoopListIterator(ArrayList<Integer>

al);

Answer 1

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;

public class LoopArrayLists {

    // Using basic while / for loop
    void printArrayListBasicLoop(ArrayList<Integer> al) {
        for (int i = 0; i < al.size(); i++) {
            System.out.println(al.get(i));
        }
    }

    // Using enhanced for loop (:)
    void printArrayListEnhancedLoop(ArrayList<Integer> al) {
        for (Integer num : al) {
            System.out.println(num);
        }
    }

    // Using basic for loop with iterator
    void printArrayListForLoopListIterator(ArrayList<Integer> al) {
        for (Iterator<Integer> it = al.iterator(); it.hasNext(); ) {
            System.out.println(it.next());
        }
    }

    // Using basic while loop with iterator
    void printArrayListWhileLoopListIterator(ArrayList<Integer> al) {
        Iterator<Integer> it = al.iterator();
        while (it.hasNext()) {
            System.out.println(it.next());
        }
    }

    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<>(Arrays.asList(3, 8, 1, 9));
        new LoopArrayLists().printArrayListBasicLoop(list);
        System.out.println();
        new LoopArrayLists().printArrayListEnhancedLoop(list);
        System.out.println();
        new LoopArrayLists().printArrayListForLoopListIterator(list);
        System.out.println();
        new LoopArrayLists().printArrayListWhileLoopListIterator(list);
        System.out.println();
    }
}