Arrays and lists are fundamental data structures in Java that allow you to store collections of elements: Arrays: In Java, an array is a fixed-size, ordered collection of elements of the same type. It provides a contiguous block of memory to store the elements and allows direct access to each element using an index. Arrays…
Read More Convert an Array to a List in JavaAccessing elements from an ArrayList is a fundamental operation in Java programming. ArrayLists are commonly used to store and manage collections of objects dynamically. Being able to retrieve elements enables you to work with the data stored within the ArrayList effectively. Whether you need to display elements, perform calculations, or manipulate the data in any…
Read More How to Get an Element from an ArrayList in Java?JSON (JavaScript Object Notation) is a widely used data interchange format that allows for easy data sharing and communication between systems. In the context of Java, JSON manipulation is crucial because it enables developers to seamlessly handle JSON data within their applications. Whether you are working with APIs, databases, or external data sources, being able…
Read More Java Jackson: Convert JSON Array to Java ListWant to learn how to merge two ArrayLists in Java? In this post, we will cover the following ways: Using the List.addAll() method Using the Java 8 Streams Using the ListUtils.union() method Merge two ArrayLists in Java using the List.addAll() method There is addAll() method from the List interface that appends all of the elements in…
Read More How to merge two ArrayLists in Java?In this post, you will learn how to Serialize and Deserialize an ArrayList in Java using the FileOutputStream and FileInputStream classes. How to Serialize an ArrayList in Java? Serialization is the process of changing the state of an object into a byte stream. For example, we use it to write some Java objects into a file. In…
Read More Serialize and Deserialize an ArrayList in JavaIn one of the previous examples, we covered how to sort an ArrayList in ascending order. In this post, you will learn how to sort ArrayList in descending order in Java. We will explore the following ways: Using the sort() method Using the Collections.sort() and Collections.reverse() methods Sort ArrayList in descending order in Java using the…
Read More Sort ArrayList in descending order in JavaWe often need to compare two ArrayList in Java. In this post, you will learn how to do that in two ways: Using the ArrayList.equals() method Using the CollectionUtils.isEqualCollection() method Compare two ArrayList in Java using the ArrayList.equals() method The ArrayList.equals() method compares two ArrayList. It compares the sizes of the lists, elements equality, and the…
Read More Compare two ArrayList in JavaIn this tutorial, you will learn how to convert ArrayList to an Array in Java using two methods: Using a for loop – I will show you how to use a ‘for loop’ to go through an ArrayList and move everything over to an Array. It’s like packing your things into a new suitcase one item at a…
Read More Convert ArrayList to Array in JavaWe often need to convert a list to a map in Java. In this lesson, you will learn how to do that with Java 8. If you are looking for more information on working with maps in Java, check out our tutorial on Map in Java. Let’s say we have a list of User objects. …
Read More Convert List to Map in Javapublic class Test {z public static void main(String[] args) { List<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)); Collections.reverse(numbers); System.out.println(numbers); } } Output: [10, 9, 8, 7, 6, 5, 4, 3, 2, 1] Reverse a List using List.add() and List.remove() methods public class Test { public static void main(String[]…
Read More Reverse a List in Javaimport java.util.*; public class Test { public static void main(String[] args) { List<String> names = new ArrayList<>(Arrays.asList(“Megan”, “Tom”, “Steve”, “Megan”, “Meliisa”, “Tom”, “John”)); Set<String> uniqueNames = new HashSet<>(names); // creating a Set from the List System.out.println(uniqueNames); } } Output: [Megan, Tom, Steve, John, Meliisa] Remove duplicates from a List in Java using the Java 8…
Read More Remove Duplicates from a List in Javaimport java.util.*; public class Test { public static void main(String[] args) { List<Integer> numbers = new ArrayList<>(Arrays.asList(7, 12, 5, 28, 97, 14, 2, 7, 8, 12, 19, 22)); Collections.sort(numbers); System.out.println(numbers); } } Output: [2, 5, 7, 7, 8, 12, 12, 14, 19, 22, 28, 97] Using the sort() method from ArrayList class public class Test…
Read More Sort a List in Javapublic class Test { public static void main(String[] args) { List<Integer> list = new ArrayList<>(Arrays.asList(7, 19, 14, 1, 12, 22, 18, 3, 28, 5)); System.out.println(“Maximum value: ” + Collections.max(list)); System.out.println(“Minimum value: ” + Collections.min(list)); } } Output: Maximum value: 28 Minimum value: 1 Finding the maximum and minimum values in List using the Java 8…
Read More Find Max and Min Values of a List in JavaLinkedList<String> list = new LinkedList<>(); List<Integer> list = new LinkedList<>(); class Test { public static void main(String[] args) { List<String> list = new LinkedList<>(); list.add(“Steve”); list.add(“Megan”); list.add(“Melissa”); list.add(“Ryan”); System.out.println(list); } } Output: [Steve, Megan, Melissa, Ryan] class Test { public static void main(String[] args) { List<String> list = new LinkedList<>(); list.add(“Steve”); list.add(“Megan”); list.add(“Melissa”); list.add(“Ryan”); List<String>…
Read More LinkedList in JavaArrayList<String> list = new ArrayList<>(); List<Integer> list = new ArrayList<>(); class Test { public static void main(String[] args) { List<String> list = new ArrayList<>(); list.add(“Steve”); list.add(“Megan”); list.add(“Melissa”); list.add(“Ryan”); System.out.println(list); } } Output: [Steve, Megan, Melissa, Ryan] Using the addAll() method, we can add all the elements of an existing list to the newly created…
Read More ArrayList in Java