“Core Java” is Sun’s term, used to refer to Java SE, the standard edition and a set of related technologies, like the Java VM, CORBA, etc. This is mostly to differentiate from others like Java ME or Java EE. “Core Java” is Oracle’s definition and refers to subset of Java SE technologies.
The Core Java technologies and application programming interfaces (APIs) are the foundation of the Java Platform, Standard Edition (Java SE). They are used in all classes of Java programming, from desktop applications to Java EE applications.
This Java tutorial will teach us how to invert a given Map using different techniques. We will learn to invert Maps with unique values and create Multimap when there are duplicate values. 1. What is an Inverted Map? An inverted Map <V, K> is an instance of the original Map<K, …
Learn to print formatted output in Java using the format() and printf() methods. Learn to format strings, date-time, floats with precision.
Learn the need and methods to join two threads in Java with examples. Learn to set wait expiration time and avoid thread deadlock conditions.
This XmlAssert tutorial teaches to create different types of XML sources and assert two XML documents for identical, similar and node values using xpath.
Collections.synchronizedMap() provides serial access to the backing Map, and ConcurrentHashMap is a thread-safe alternative to HashMap.
In XmlUnit 2.x tutorial, learn to create different XML sources, normalizing with decorators and comparing for identical, similar and XPaths.
Learn to write test result assertions using the JSONassert with easy-to-understand examples. We can use this tutorial as JSONassert cookbook for quick reference.
The HashMap, part of the Java Collections framework, is used to store key-value pairs for quick and efficient storage and retrieval operations.
The backbone of Java concurrency are threads. A thread is a lightweight process with its own call stack but can access shared data of others.
A collection is a group of objects. Java Collections framework consists of classes and interfaces to work with lists, sets, maps and queues.
This Java guide will take us through Java Collections framework. We will understand the core concepts and performing the basic operations.
Java ArrayList class represents a resizable array of objects which allows us to add, remove, find, sort and replace elements.
Lists are the core building blocks of the Collections framework. These tutorials will teach us the basics of different List classes in Java.
Maps in Java are the core building blocks of the Collections framework. These tutorials will teach the basics of working with different maps.
Learn to use Java TreeMap, Spring’s LinkedCaseInsensitiveMap and Apache common’s CaseInsensitiveMap for creating case-insensitive Maps.
Learn the different ways of creating and starting new threads using Thread class, Runnable interface, ExecutorService and virtual threads.
A submap is a portion or part of a map between the keys of a specific range. Learn how to get submap from map in Java with different ways.
Learned to create a web scrapper in Java. This demo application introduces various components needed to create a working web scrapper.
Learn to create and work with the Java EnumMap in detail, difference between EnumMap and HashMap and the practical usecases for the same.
Learn to set up and configure JsonPath with examples of extracting information from JSON documents by applying filters using the predicates.
Learn to make HTTP POST and PUT requests in tests with REST-assured including sending the request body, params, headers and authentication.
Learn to remove the last character from a String, either using the indices or only matching criteria. Learn to handle null and empty values.
Learn to send requests with XML request body (either from an XML file or using custom objects) using REST-assured APIs with examples.
Learn to use REST-assured library to write automated tests for REST API testing with examples, specially useful in BDD style development.
A nested Map is Map inside another Map. Learn to create a nested HashMap and add, remove and iterate over the elements with examples.
In this post, we are going to discuss thread priorities in detail and the different types of thread priorities in Java, and how a thread scheduler executes various threads based on their priorities. We will also see how we can set thread priority of a thread and how we can …
Learn to create immutable and unmodifiable maps in Java using Java collections APIs and Guava’s ImmutableMap class.
Learn to convert a Stream into immutable/unmodifiable collection using Stream methods such as stream() and Collectors.toUnmodifiableList().
Learn the differences between TreeMap and HashMap in Java as both implements the Map interface but differ in functionality and performance.
Learn to kill a running thread in Java using a boolean flag and sending interrupt message. Sending an interrupt is a much better approach.
Learn to use BlockingQueue drainTo() method for draining the queue items (polling all or specific number of elements) into a Collection.
Learn to prepare the data (to write) and then append the new rows after the last row in an existing sheet using Apache POI in Java.
Learn the different ways to set a custom name for a thread using Thread constructor and setName(). Also, learn to get the name of a thread.
Learn to read an excel file containing multiple sheets in Java using the Apache POI and SAX parser, and adding custom event handler functions.
IdentityHashMap implements the Map interface and has almost the same features as HashMap. It uses reference equality on key search operations.
ConcurrentMap is an interface in Java Collections and used to create a thread-safe Maps. It stores the key-value pairs in a synchronized way.
Debugging Java streams can be challenging. In this post, learn to debug streams as their elements are processed in the chained method calls.
Learn to make the main thread wait for other threads to finish using the ExecutorService or ThreadPoolExecutor methods and CountDownLatch.
Learn about the Java WeakHashMap, strong & weak references with examples. Also, learn the differences between WeakHashMap and HashMap.
Java ternary operator is a conditional operator and can be used as a replacement for a simple if-else statement or a switch statement.
Java 21 Structured concurrency (JEP-428) aims to simplify concurrency by treating multiple tasks running in different threads as a single unit of work.
In Java, Virtual threads (JEP-425) are JVM managed light-weight threads that will help in writing high throughput concurrent applications.
Learn to create and inject mocks, record expectations, verifications, and argument matching using the JMockit in JUnit tests with examples.
Learn to use EasyMock with JUnit 4 and 5 to create test mocks, record and replay the expectations and verify method invocations on mocks.
Learn to use MockWebServer to mock APIs, later consume these API in JUnit tests using WebClient, verifying responses and servers stats.
The microservices architecture allows us to develop, test and deploy different components of an application independently. Though such a component can be developed independently, testing this in isolation can be challenging. For a true integration testing of a microservice, we must test its interaction with other APIs. WireMock helps in …
Java Regex or regular expressions can add, remove, isolate, and generally fold, spindle, and mutilate all kinds of text and data.
A Java array is a container object that holds a fixed number of homogeneous values (of a single type) in a contiguous memory location.
Learn to copy or pipe the byte[] data from InputStream to OutputStream for small streams and also for large streams over 2 GB.
Learn to convert a Reader to InputStream and also convert InputStream to Reader in this short Java IO tutorial.
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