How to Convert String Array Into Int Array in Java

1. Convert string Array to int Array by Using the parseInt() Method in Java
2. Convert string Array to int Array by Using the Stream API in Java
3. Convert string Array to int Array by Using the Stream API in Java

This tutorial introduces how to convert string arrays to int arrays in Java. You’ll see some example programs so that you can understand this concept better.

An array that holds string values is a string array; similarly, an int array contains only integer values. In this article, you’ll learn how to convert a string array into an int array by using some built-in methods in Java, such as the parseInt() function and the Stream API.

Convert string Array to int Array by Using the parseInt() Method in Java

In this example, we use the parseInt() method of the Integer class that returns the integer after the conversion. Since it works with a single value, we use a for loop to convert all the elements of the string array into int and assign them to an int array simultaneously. We used the second loop to check if the conversion taking place is fine. See the example below:

public class SimpleTesting {
  public static void main(String[] args) {
    String[] arr = new String[] {"2", "34", "55"};
    int[] arr2 = new int[3];
    for (int i = 0; i < arr.length; i++) {
      arr2[i] = Integer.parseInt(arr[i]);
    }
    for (int i = 0; i < arr2.length; i++) {
      System.out.println(arr2[i]);
    }
  }
}

Output:

2
34
55

Convert string Array to int Array by Using the Stream API in Java

If you’re working with Java 8 or a higher version and familiar with the Stream API, you can use the code below. In this example, we used the toArray() method, which returns an integer array. Here’s the sample program:

import java.util.stream.Stream;
public class SimpleTesting {
  public static void main(String[] args) {
    String[] arr = new String[] {"2", "34", "55"};
    Integer[] arr2 = Stream.of(arr).mapToInt(Integer::parseInt).boxed().toArray(Integer[] ::new);
    for (int i = 0; i < arr2.length; i++) {
      System.out.println(arr2[i]);
    }
  }
}

Output:

2
34
55

Convert string Array to int Array by Using the Stream API in Java

This example is similar to the code block above, except that it returns an array of the primitive int value. The previous example returns an array of integers(wrapper class).

import java.util.Arrays;
public class SimpleTesting {
  public static void main(String[] args) {
    String[] arr = new String[] {"2", "34", "55"};
    int[] arr2 = Arrays.stream(arr).mapToInt(Integer::parseInt).toArray();
    for (int i = 0; i < arr2.length; i++) {
      System.out.println(arr2[i]);
    }
  }
}

Output:

2
34
55