How to sort a HashMap in Java 8 by keys and values using Stream and Lambda Expressions

Technically, you cannot sort a HashMap in Java because it doesn't guarantee any order. So, even if you add entries in sorted order they will be placed randomly and you won't be able to iterate over map in sorted order of keys or values. Though, if you want to process keys, values or entries of an HashMap in sorted order, you can get the data from the HashMap and then potentially use a TreeMap (when you want to sort a HashMap by key) or LinkedHashMap (when you want to sort a HashMap by value) to store entries in sorted order. This is also the way, we used to sort HashMap before Java 8. 

Java 8 Comparator comparing() and thenComparing() Example - Tutorial

Hello Java programmers, you may know that the JDK 8 has added a lot of new methods into the Comparator interface which makes comparing and sorting objects in Java really easy. Two such methods are called comparing() and thenComparing() which was added in the java.util.Comparator interface. These methods accept a key extractor function and return a Comparator that can compare to that key. The key must be Comparable though like String, Integer, or any Java class which implements java.lang.Comparable interface, I mean the key must implement Comparable interface. 

7 Examples of Comparator and Comparable in Java 8

Hello guys, you may know that Java 8 introduced a number of features to simplify the code and make it more readable. One such feature is enhancements of Comparator and Comparable interfaces. The Comparator interface provides a way to compare two objects and sort them based on specific criteria. The Comparable interface is used to compare the objects of the same class and sort them based on their natural order. In this article, we'll explore 7 different examples of Comparator and Comparable in Java 8. We'll see how we can use them to sort objects based on various criteria, such as alphabetical order, length, age, and salary. These examples will give you a better understanding of how Comparator and Comparable work and how you can use them to improve your code.