How to Convert an `int[]` to `Integer[]` for Mapping in Java?

Bridging int[] to Integer[] for Mapping in Java: A Comprehensive Guide

When grappling with large datasets, sometimes you need to count the frequency of specific combinations of values. This is akin to counting word frequencies in a document.

To delve into this task effectively, you can employ a Map where the keys represent int[] arrays, and the values are running counts. However, Java's Map collection does not accept primitive types as keys, necessitating a conversion to their wrapper classes, like Integer[].

To seamlessly perform this conversion, you can leverage the power of Java 8 streams. Here's how:

Native Java 8 (One Line)

With Java 8's stream API, you can convert int[] to Integer[] concisely:

<code class="java">int[] data = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

// Option 1: To boxed array
Integer[] what = Arrays.stream(data).boxed().toArray(Integer[]::new);

// Option 2: To boxed list
List<Integer> you = Arrays.stream(data).boxed().collect(Collectors.toList());</code>

Remember, using Integer[] as map keys is generally not recommended due to potential performance limitations. However, for conversion purposes, Java 8 streams offer a robust solution.

The above is the detailed content of How to Convert an `int[]` to `Integer[]` for Mapping in Java?. For more information, please follow other related articles on the PHP Chinese website!