How do I Sort Java Collections by Custom Fields?

Sorting Java Collections by Custom Field

You have a Java collection that you desire to sort by a field. Here's how you can accomplish this:

Using a Comparator

If your collection elements don't implement Comparable, you can utilize a Comparator to specify the sorting criteria:

Comparator<CustomObject> comparator = (left, right) -> left.getId() - right.getId();
Collections.sort(list, comparator);
System.out.println(list);

Using Comparable Interface (Java 8 )

If your CustomObject implements Comparable, you can directly apply Collections.sort():

Collections.sort(list);

Advanced Sorting Options

For more convenient syntax in Java 8 , consider the following options:

Collections.sort(list, (left, right) -> left.getId() - right.getId());
list.sort((left, right) -> left.getId() - right.getId());
list.sort(Comparator.comparing(CustomObject::getId));

Remember, the initial code used for the comparator approach can be applied to Java 8 as well.

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