Java – Convert int[] to Integer[] example

By mkyong | Updated: February 22, 2014

Viewed: 2,825 (+47 pv/w)

Tags: convert

Examples show you how to convert between int[] and its’ wrapper class Integer[].

1. Convert int[] to Integer[]

	public static Integer[] toObject(int[] intArray) {

		Integer[] result = new Integer[intArray.length];
		for (int i = 0; i < intArray.length; i++) {
			result[i] = Integer.valueOf(intArray[i]);
		}
		return result;
	}

2. Convert Integer[] to int[]

	public static int[] toPrimitive(Integer[] IntegerArray) {

		int[] result = new int[IntegerArray.length];
		for (int i = 0; i < IntegerArray.length; i++) {
			result[i] = IntegerArray[i].intValue();
		}
		return result;
	}

The theory is simple, create a new array, and dump the old value inside.

1. Full Example

Review a full example to show you how it works.

package com.mkyong.test;

public class ArrayConvertExample {

	public static void main(String[] args) {

		int[] obj = new int[] { 1, 2, 3 };
		Integer[] newObj = toObject(obj);

		System.out.println("Test toObject() - int -> Integer");
		for (Integer temp : newObj) {
			System.out.println(temp);
		}

		Integer[] obj2 = new Integer[] { 4, 5, 6 };
		int[] newObj2 = toPrimitive(obj2);

		System.out.println("Test toPrimitive() - Integer -> int");
		for (int temp : newObj2) {
			System.out.println(temp);
		}

	}

	// Convert int[] to Integer[]
	public static Integer[] toObject(int[] intArray) {

		Integer[] result = new Integer[intArray.length];
		for (int i = 0; i < intArray.length; i++) {
			result[i] = Integer.valueOf(intArray[i]);
		}
		return result;

	}

	// Convert Integer[] to int[]
	public static int[] toPrimitive(Integer[] IntegerArray) {

		int[] result = new int[IntegerArray.length];
		for (int i = 0; i < IntegerArray.length; i++) {
			result[i] = IntegerArray[i].intValue();
		}
		return result;
	}

}

Output

Test toObject() - int -> Integer
1
2
3
Test toPrimitive() - Integer -> int
4
5
6

2. ArrayUtils Example

To save you time, uses the ArrayUtils class from the Apache common library, it does the same thing.

package com.mkyong.test;

import org.apache.commons.lang3.ArrayUtils;

public class ArrayConvertExample {

	public static void main(String[] args) {

		int[] obj = new int[] { 1, 2, 3 };
		Integer[] newObj = ArrayUtils.toObject(obj);

		System.out.println("Test toObject() - int -> Integer");
		for (Integer temp : newObj) {
			System.out.println(temp);
		}

		Integer[] obj2 = new Integer[] { 4, 5, 6 };
		int[] newObj2 =	ArrayUtils.toPrimitive(obj2);

		System.out.println("Test toPrimitive() - Integer -> int");
		for (int temp : newObj2) {
			System.out.println(temp);
		}

	}

Test toObject() - int -> Integer
1
2
3
Test toPrimitive() - Integer -> int
4
5
6

References

1. Apache ArrayUtils JavaDoc
2. Primitive wrapper class