“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.
Learn what a Semaphore and a Reentrant Lock are along with practical examples. We will also explore some of the main differences between the two and the use cases where we can use these while working in a multithreaded application. 1. What is a Semaphore? A Semaphore is a Thread …
Learn to remove all the occurrences of an element from a given List using Java loops, list methods and Stream API.
Flattening a nested list may seem hard at the beginning, but it’s not. It can be easily done using only plain Java, streams, or external libraries.
Object-oriented programming (OOP) is a programming model that organizes software design around data or objects. Learn how Java supports OOP.
Learn to convert a List to a Map in Java using Streams, Commons collections, and Guava including Multimap class for duplicate list items.
Java Streams have gained a lot of awareness and being able to iterate through with indices can be helpful. Learn a few ways with examples.
Learn to remove and update elements of a Collection using Stream.filter() and Strea,map() methods in Java with examples.
Learn to create a List from array using Arrays.asList(array) and new ArrayList(Arrays.asList(array). Learn their differences with examples.
Learn to convert a given Java object into a Map using different solutions including Jackson ObjectMapper, Gson and Java reflection.
Learn to filter a Java HashMap by List of keys and collect the matching entries into a submap or matching values in a List.
Learn IllegalMonitorStateException, when it is thrown with examples. We will also see how we can prevent our code from raising this exception
Learn to round off a given floating point number to 2 decimal points in Java. As the best practice, always use the Decimal class with rounding mode set to HALF_EVEN.
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.
A Java Map stores unique keys with one value each. Quick put/get/merge/computeIfAbsent examples, a comparison of HashMap, LinkedHashMap, TreeMap, ConcurrentHashMap, EnumMap, Hashtable and Map.of(), and all our Map tutorials grouped by topic.
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.
Append rows to an existing Excel sheet with Apache POI 5.5.1. We find the next free row, keep the date and number formats, add rows before a totals row and save through a temp file so a failed write never empties the spreadsheet.
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.
HowToDoInJava provides tutorials and how-to guides on Java and related technologies.
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