The JDK 8 has added several useful methods in existing interfaces e.g. java.util.Map, java.util.Collection, and java.util.concurrent.ConcurrentMap. Thanks to default methods, the much-needed evolution of existing interfaces becomes possible. Out of many useful methods, one method which stands out to me is the compute() method, which allows you to update a value in ConcurrentHashMap atomically. As per Java documentation, The compute() function tries to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). The entire function is performed atomically.
How to use LinkedList in Java? Singly LinkedList and Doubly LinkedList Example Tutorial
Hello friends, we meet again on our journey to Java. I hope you guys are enjoying Java and are trying hands-on too. Today we are gonna discuss a very easy topic (yeah, I mean it :p). But, do not get carried away just by "easy", this is the hottest topic asked in various interviews, exams, and development purposes too. So, what's the wait? Let's start! As usual, let's start with a scenario. Let's say you want a data structure that stores data in a sequential manner, like an array. But, you don't know the size yet while initializing the data structure. Arrays don't support that, they need a size beforehand. So, what should we do? Do not worry, as Java is here to help us again. Let's explore it then!
How to get First and Last Element of LinkedList in Java [Example]
Hello guys, if you are wondering how to get the first and last element from Java LinkedList then you have come to the right place. Earlier, I have shared the best Data structure and algorithms courses and in today's post, I will teach you how to get the first and last element of a linked list in Java. This is one of the common coding problems but we will see it from different angles. In Java, you don't need to write and create your own LinkedList, there is a built-in class called java.util.LinkedIn and you can use that class whenever you need a linked list data structure.
Difference between Thread.yield and Thread.sleep in Java? Answer
Sleep vs yield in Java
Sleep and yield are two methods that are used to get CPU back from Thread to Thread Scheduler in java but they are completely different than each other. The major difference between Sleep vs yield is that sleep is more reliable than yield and it's advised to use sleep(1) instead of yield to relinquish CPU in multi-threaded Java applications to give an opportunity to other threads to execute. In this Java tutorial, we will what are the differences between yield and sleep in Java. But before seeing the difference between sleep and Yield let's see some similarities between yield and sleep in Java
Difference between Serializable vs Externalizable in Java - Interview Question
What is the difference between Serializable and Externalizable in Java is famous core Java interview questions and for some of them its one of those difficult Java question, which no one wants to see in Java interview. I was in that category until I read Effective Java and explored How Serialization works in Java and find out more about the Serialization process. What makes Serialization questions tricky is, Serialization as a persistence mechanism is not very popular. Many programmers prefer databases, memory-mapped files, or simple text files over Serialization. But Serialization has a distinguished advantage over these mechanisms.
How to delete multiple elements from a LinkedList in Java? SubList() Example
Hello guys, if you are looking for an easy way to remove a sub set of elements
from a LinkedList in Java then you have come to the right place. In the past,
I have shown you
how to sort a LinkedList in Java
and
how to create your own linked list implementation in Java
and in this article, I am going to introduce you with an interesting method
which can be used to delete a portion of LinkedList in Java in shot. Yes,
there is a method exists but not many Java developer knows about it. The
method is called subList() and you
can use this method with clear method in Java to delete a portion of linked
list in one shot.
What is TreeMap in Java? HashMap vs TreeMap Example Tutorial
Hello guys, I hope you all are doing well and having lots of fun reading and learning Java Collections together. Today we are here a meet again on our journey of Java. I hope you all have seatbelts buckled up as today it's gonna be an adventurous ride while learning something that is most used in many production applications, coding, and whatnot. Today's topic, TreeMap in Java is very important because it holds a very significant feature Java development kit provides. This is also one class which many Java developer doesn't pay attention but it is really used for many use cases. Most Java developer just keep their attention to ArrayList, HashSet, and HashMap and thus missing out on many cool Java collection classes like TreeMap, WeakHashMap, and LinkedHashMap which saw earlier.
How ThreadLocal variables works in Java? Explained
Hello guys, ThreadLocal variable is an interesting concept and class from Java API. Not many developer knows about it and very few know how to use it correctly. A couple of years ago it was also a popular Java interview questions for experienced developer but over the years, it lost the popularity as more and more people are now asking about Phaser, CompletableFuture, ForkJoinPool, and other newly added concurrency utilities. ThreadLocal variables, as name suggests is local to thread, which means every thread has there own copy. This means they don't need to look at the main memory when they want to use that variable and best thing is that the variable is not even shared between threads so no locking or synchronization is needed.
Difference between JIT and JVM in Java? Answered
The main difference between JIT and JVM is that JIT is part of JVM itself and its main function is to improve the performance of JVM by directly compiling some hot code (code that executes above a certain threshold) into native instruction. JIT stands for Just In time compilation and JVM stands for Java Virtual Machine. JVM is a virtual machine used in Java programming platforms to execute or run Java programs. The main advantage of JVM is that JVM makes Java platform-independent by executing bytecodes. Java source code is compiled into class files, which contain bytecode.
Visitor Design Patterns In Java Examples Tutorial
Hello guys, if you want to learn Visitor design pattern in Java then you have come to the right place. Earlier, I have covered many design patterns like Decorator, Strategy, State, Composite, Adapter, Command, Template, Factory, Observer and even few Microservice patterns like SAGA and Database per service and in this article, I will talk about Visitor Design Pattern and how to implement in Java. You will learn things like what is Visitor design pattern, what problem it solves, what are pros and cons of Visitor design pattern, when to use Visitor pattern as well as any alternatives of Visitor Pattern in Java. I will also show you a real world example of Visitor design pattern, but, before we get to the 5 best examples that will teach you all about design patterns in Java, let me tell you a little bit more about what it really is.
Difference between 32-bit vs 64-bit JVM in Java?
Hello Java Programmers, if you want to learn Java virtual Machine in-depth and wondering what is the difference between a 32-bit and 64-bit JVM and which one should you use and why? then you have come to the right place. Earlier, I have shared the best JVM books and online JVM courses and in this article, I am going to talk about 32-bit vs 64-bit JVM and their pros and cons. This is also a common Java interview question for beginners and intermediate Java programmers. I have tried to answer this question to the point that's why this article is a short but informative one. You will find out what they are, how they are different, how much heap size, and the pros and cons of each of them.
10 Examples Of Mockito + JUnit in Java for Unit Testing
Hello guys, if you are writing unit test in Java then you know how difficult it is to write especially if you are testing a class which is dependent upon other class like HttpClient and you cannot connect to actual server. At those time, a mocking library like Mockito comes to rescue. Given the increased focus on unit testing and code coverage, I have find myself using Mockito more and more along with JUnit in last a couple of years but I haven't written many articles on Mockito yet but that is chaging now. In this article, I am going to share 10 essential Mockito examples which I belive every Java programmer should know. But, before we get to the 10 best examples that will teach you everything there is to know about Mockito in Java, let me tell you a little bit more about what it really is.
How to convert Java 8 Stream to Array and ArrayList in Java? Example Tutorial
It's relatively easy to convert a Stream to an array in Java 8 by using the toArray() method of java.util.Stream class. By using this method you can convert any type of Stream to a corresponding array like a Stream of Strings can be converted into an array of String, or a Stream of integers can be converted into an array of Integers. The Stream.toArray() method is also overloaded, the one which doesn't take any parameter returns an Object[] which might not be very useful, particularly if you want to convert Stream of T to an array of T.
Array length vs ArrayList Size in Java [Example]
One of the confusing parts in learning Java for a beginner to understand how to find the length of array and ArrayList in Java? The main reason for the confusion is an inconsistent way of calculating the length between two. Calling size() method on arrays and length, or even length() on ArrayList is a common programming error made by beginners. The main reason for the confusion is the special handling of an array in Java. Java native arrays have built-in length attribute but no size() method while the Java library containers, known as Collection classes like ArrayList<>, Vector<>, etc, all have a size() method.
How to create an ArrayList from Array in Java? Arrays.asList() Example Tutorial
One of the common problems faced by junior and less experienced Java developers is converting an array to ArrayList e.g. they are getting an array from somewhere in their code and then want to create an ArrayList out of that so that they can add more elements and use other library methods which operate with ArrayList or List. The simplest way to convert an array to ArrayList is by using the Arrays.asList() method, which acts as a bridge between Collection classes and array data structure. This method returns a List that contains elements from an array.
Is it Possible to add static or private methods in Java interface?
Can you add a static or private method in an interface in Java? or is it possible to add a private or static method in Java interface? or can you add a non-abstract method on an interface in Java? are a couple of popular Java interview questions which often pop up during telephonic interviews. Well, prior to Java 8, it wasn't possible to add non-abstract methods in Java but nowadays you can add non-abstract static, default, and private methods in the Java interface. The static and default methods were supported as part of interface evolution in Java 8 and you can add private methods on an interface from Java 9 onwards.
10 Examples Of Scanner Class In Java
Hello guys, if you want to learn about Scanner class in Java, one of the most popular class to read input from command prompt or console then you have come to the right place. In this article, I will explain how to read input from command prompt, what is Scanner class and how you can use Scanner class to read various data types like String, int, long, boolean directly from console. You must have heard about famous nextInt(), nextDouble() methods which can read integer and double values from command prompt or console. But, before we get to the 10 best examples that will teach you everything you need to know about scanner class in Java, let me tell you a little bit more about what it really is.
What is Diamond operator in Java? Example Tutorial
Hello guys, if you are reading Java code and come across closed angle bracket with a diamond like shape and wondering what they are and what they do then you have come to the right place. They are known as Diamond operator in Java and I will explain you what they are and where should you use them in this article. The Diamond operator is a relatively new operator in Java which was first introduced in JDK 7 to improve type inference and reduce boilerplate Java coding. It is denoted with a closed angle bracket that resembles the shape of a diamond (<>) and that's why it's called the Diamond operator. If used correctly it can reduce typing and boilerplate coding in Java and result in much cleaner and readable code especially when you use Generics.
Parallel Array Sorting in Java - Arrays.parallelSort() Example
There are multiple ways to sort array in Java. For example, you can use Array.sort() method to sort any primitive or object array in Java but Java 8 presents a new feature that is useful to sort array’s elements. It can implemented by using the package “java.util.Arrays” which represents several methods to sort the array. The biggest benefit is that parallel array sorting is that its faster than any other sorting method due to usage of multithreading conception. So multiple threads can break the array into parts and work simultaneously to sort it.
Difference between Thread vs Process in Java? Example
Thread and Process are two closely related terms in multi-threading and the main difference between Thread and Process in Java is that Threads are part of the process. i.e. one process can spawn multiple
Threads. If you run
a Java program in UNIX based system e.g. Linux and if that program creates
10 Threads, it still one process and you can find that by using ps
-ef | grep identifier command which is one of the most popular
use of grep command in UNIX, Where identifier is UNIX the text which can be used as regular
expression to find that Java process.
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