Quick Answer

Order collections in Java.

Understanding the Issue

Java provides multiple ways to sort lists using Comparator and natural ordering.

The Problem

This code demonstrates the issue:

Java Error 
List<String> names = Arrays.asList("Bob", "Alice", "Charlie");

The Solution

Here's the corrected code:

Java Fixed 
// Natural order:
Collections.sort(names);

// Custom comparator:
names.sort(Comparator.comparing(String::length));

// Reverse order:
names.sort(Comparator.reverseOrder());

// Java 8+ syntax:
names.sort((a, b) -> a.compareTo(b));

// Object sorting:
persons.sort(Comparator
    .comparing(Person::getLastName)
    .thenComparing(Person::getAge));

Key Takeaways

Use Comparator for flexible sorting criteria.