adojos

public static void convertUsingForLoop(){
List<Integer> inputList = Arrays.asList(2,4,6,8,10);
int[] outputArray = new int[inputList.size()];
for(int i = 0; i < inputList.size();i++){
		outputArray[i] = inputList.get(i);
	}
	//print the elements in the array
	for (int num : outputArray) {
		System.out.print(num + " ");
	}

adojos

public static void convertUsingStream() {
List<Integer> inputList = Arrays.asList(2, 4, 6, 8, 10);
	Stream<Integer> inputStream = inputList.stream();
	Object[] objArray = inputStream.toArray();

//print the elements in the array
	for (Object num : objArray) {
		System.out.print(num + " ");
	}
}

adojos

public static void convertUsingStream2() {
List<Integer> inputList = Arrays.asList(2, 4, 6, 8, 10);
Stream<Integer> inputStream = inputList.stream();
	Integer[] intArray = inputStream.toArray((num) -> new Integer[num]);
	
//print the elements in the array
	for (int num : intArray) {
		System.out.print(num + " ");
	}
}

adojos

public static void convertUsingToArray() {
List<Integer> inputList = Arrays.asList(2, 4, 6, 8, 10);
	Object[] objArray = inputList.toArray();

//print the elements in the array
	for (Object num : objArray) {
		System.out.print(num + " ");
	}
} 

adojos

public static void convertUsingToArray2() {

List<Integer> inputList = Arrays.asList(2, 4, 6, 8, 10);
	Integer[] outputArray = inputList.toArray(new Integer[inputList.size()]);
	
//print the elements in the array
	for (int num : outputArray) {
		System.out.print(num + " ");
	}
}

adojos

public static void usingForLoop(){
List<Integer> input = Arrays.asList(5,10,15,20,10,5,35,40,10,25);
List<Integer> output = new ArrayList<Integer>();
for(Integer num:input){
if(!output.contains(num)){
  		output.add(num);
  		}
}
for(Integer num:output){
  		System.out.print(num+" ");

adojos

public static void usingHashSet(){
List<Integer> input = Arrays.asList(5,10,15,20,10,5,35,40,10,25);
Set<Integer> output = new HashSet<Integer>(input);
for(Integer num:output){
System.out.print(num+" ");
}
}

adojos

public static void usingLinkedHashSet(){
List<Integer> input = Arrays.asList(5,10,15,20,10,5,35,40,10,25);
	Set<Integer> output = new LinkedHashSet<Integer>(input);
	for(Integer num:output){
		System.out.print(num+" ");
	}
}

adojos

public static void usingSetAddAll(){
List<Integer> input = Arrays.asList(5,10,15,20,10,5,35,40,10,25);
Set<Integer> output = new LinkedHashSet<Integer>();
output.addAll(input);
for(Integer num:output){
System.out.print(num+" ");
  }
}

adojos

public static void usingStream(){
List<Integer> input = Arrays.asList(5,10,15,20,10,5,35,40,10,25);
Stream<Integer> streamWithDuplicates = input.stream();
Stream<Integer> streamWithoutDuplicates = streamWithDuplicates.distinct();
List<Integer> output = streamWithoutDuplicates.collect(Collectors.toList());
	for(Integer num:output){
		System.out.print(num+" ");
	}
}