How to Sort a Java List Based on the Order of Another List?

Sorting One Java List Based on Another

When reordering elements in a list (listA), users may desire to retain the new order upon retrieval. Due to constraints, it may be necessary to sort listA after retrieval based on another list (listB) that defines the desired order.

To achieve this sorting, you can leverage Java's Collections.sort method with a custom comparator. The comparator function should compare elements based on their indices in listB.

Java 8 Solution

<code class="java">Collections.sort(listToSort, Comparator.comparing(item -> listWithOrder.indexOf(item)));</code>

Improved Java 8 Solution

<code class="java">listToSort.sort(Comparator.comparingInt(listWithOrder::indexOf));</code>

This improved solution uses comparingInt instead of comparing, providing enhanced performance.

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