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How to Convert a LinkedList to an Array in Java? Example

You can convert a LinkedList to an array in Java by using the toArray() method of the java.util.LinkedList class. The toArray() method accepts an array of relevant type to store contents of LinkedList. It stores the elements in the array in the same order they are currently inside the LinkedList. By using the toArray() method you can convert any type of LinkedList e.g. Integer, String or Float to any type of Array, only catch is this you cannot convert a LinkedList to an array of primitives i.e. a LinkedList of Integer cannot be converted into an array of ints by using toArray() method, but you can convert it to array of Integer objects, that's perfectly Ok.

5 ways to Compare String Objects in Java - Example Tutorial

here are many ways to compare String in Java e.g. you can use equals() and equalsIgnoreCase() for equality check and compare() and compareTo() for ordering comparison. You can even use the equality operator == to perform reference based comparison e.g. to check both the String reference variable points to the same object. In general, equals() is used to check whether the value of given String is same i.e. they contain same characters in the same sequence or not e.g. "Groovy".equals("Groovy") will be true if you compare them using equals() method. You can also use equalsIgnoreCase() to check if they are equal irrespective of case e.g. "Apple" and "apple" will be same if you compare them using equalsIgnoreCase() method.

How to Count number of 1s (Set Bits) in Given Bit Sequence in Java

Good morning folks, In today's article, we are going to discuss one of the frequently asked bit manipulation based interview question, how do you count the number of set bits in given bit sequence?  Bit Manipulation is an important topic on programming interview and a good programmer should have sufficient knowledge and skill to work with binary numbers. This kind of questions tests that skill of the programmer. Sometimes, it is also asked as for how to count the number of 1s (ones) in given number? Both are the same question because 1 is also known as set bit.  For example, if given input is 1000110010 than your program should return 4, as three are only four set bits in this bit sequence.

Can you Make a Class Static in Java? Interview Question

This is one of the tricky questions in Java because there is no straight forward Yes and No answer here. You cannot make a top level class static in Java but Yes, you can make a nested class static in Java. In fact, it is even advised (see Effective Java) to prefer a nested static class in Java than normal inner classes. Now, the question comes what is a top level class and what is a nested class in Java? Well, you can declare multiple classes in a single Java source file. A class is said to be top level if it is not inside any other class and a class which is inside another class is known as nested class. You can create nested class inside another top level or another nested class in Java. This is the class which can be static in Java.

Top 20 Hibernate Interview Questions for Java J2EE Programmers

Hibernate is one of the most popular persistent frameworks in Java world. Hibernate offers object to relational (ORM) solution which frees Java developers from writing tedious, hard to read and cluttered JDBC code converting SQL columns into Object properties. Apart from freeing Java developer from writing JDBC and database interaction code, Hibernate also offers the out-of-box solution on caching, proxying and lazy loading which drastically improves the performance of your Java Web application. Given it's important in Java Web application development field Hibernate has become of one of the most sought-after skill and goes hand in hand with Spring framework. That's why Spring and Hibernate interview questions are also very popular in Java interviews, particularly for web development positions.

3 Examples to Loop Through a List in Java 8

3 ways to Loop through a List in Java
There are multiple ways to traverse or loop through a List in Java e.g. by using an Iterator, by using an enhanced for loop of Java 5, and not the forEach() method of Java 8. Given a List is an index based collection if you know the index you can retrieve an object from List and because of this, you can also use traditional for loop which keeps count for iterating List. Now the question is whether should you use the Iterator or enhanced for loop, or the forEach() method of Java 8 for looping over List in Java. Well, it depends on what you are doing with the object, if you need to remove some objects from List than iterating using Iterator is best choice to avoid ConcurrentModificationExceptionbut if you are not removing any element and just doing some operation with each element than enhanced for loop is much cleaner ways to do that. 

How to Send HTTP Request from Java Program - Example Tutorial

If you are thinking is it possible to send an HTTP request from a Java program and if yes, how to send a simple HTTP GET request in Java, then you have come to the right place. In this article, I'll show you how you can use the HttpURLConnection class from java.net package to send a simple HTTP request in Java. But, first let me answer your first question, is it possible to send HTTP request in Java? Yes, it's possible and you can send any kind of HTTP request e.g. GET, POST, PUT, DELETE, HEAD, or PATCH. The java.net package provides a class called HttpURLConnection, which can be used to send any kind of HTTP or HTTPS request from Java program.

Is Java The best language to learn Programming/Coding for Beginners?

I often receive questions like which is a good programming language to learn first, Is Java a good programming language to start with,  how good Java is as a first programming language, which is the best programming language for beginners, or shall I start with Java or Python. Well, the answer to all these questions is, Java is one of the most popular programming languages and there are the lot of reasons to learn Java, starting with Job opportunity to leverage community support. In the context of starting programming or choosing Java as the first language, my biggest reason is that it's simpler to learn. The last generation of programmers started learning to programme using languages like BASIC and then grew up learning C and C++ with Java as their second or third programming language.

JDBC - Difference between PreparedStatement and Statement in Java

If you have worked with database interfacing with Java using JDBC API then you may know that the JDBC API provides three types of Statement for wrapping an SQL query and sending for execution to the database, they are aptly named as Statement, PreparedStatement, and CallableStatement. First one, Statement is used to execute normal SQL queries e.g. select count(*) from Courses. You can also use it to execute DDL, DML and DCL SQL statements. The second one, PreparedStatement is specialized to execute parameterized queries e.g. select * from Courses where courseId=?, you can execute this SQL multiple times by just changing the course parameters. They are compiled and cached at database end, hence quite fast for repeated execution.

Difference between ISNULL and COALESCE T-SQL Function in Microsoft SQL Server - Interview Questions

Even though both ISNULL() and COALESCE() function provides alternate values to NULL in T-SQL and Microsoft SQL Server e.g. replacing NULL values with empty String, there are some key differences between them, which is often the topic of SQL Server interview. In this article, you will not only learn the answer to this question but also learn how to use COALESCE and ISNULL function properly. One the main difference between them is that  COALESCE() is a standard SQL function but ISNULL() is a Microsoft SQL Server specific, which means it's not guaranteed to be supported by other database vendors like Oracle, MySQL or PostgreSQL.

How to Convert a Comma Separated String to an ArrayList in Java - Example Tutorial

Suppose you have a comma-separated list of String e.g. "Samsung, Apple, Sony, Google, Microsoft, Amazon" and you want to convert it into an ArrayList containing all String elements e.g. Samsung, Apple, Google etc. How do you do that? Well, Java doesn't provide any such constructor or factory method to create ArrayList from delimited String, but you can use String.split() method and Arrays.asList() method together to create an ArrayList from any delimited String, not just comma separated one. All you need to do is first split the given String on delimiter e.g. comma using the split() method, this will give you an array of String. Now, you can pass that array to Arrays.asList() method to create a List, but remember this would be fixed length list and not truly an ArrayList.

3 Books and Courses to Learn RESTful Web Services using Spring and Java

Even though the Spring in Action 4th Edition is a good book to learn Spring framework, its not enough to learn intricacies of developing RESTful Web Service using Spring Frameowrk. It does have a chapter on developing RESTful Web Services and nicely explains concepts like @RestController, @ResponseBody, @ResponseStatus, HTTP message converters, content negotation but that barely touch the surface of developing a production quality RESTFul Web Service. There are many other things e.g. filtering, pagination, error handling, and security of RESTful Web services using Spring and Spring security which is not covered.

10 Examples of Array Data Structure in Java - Tutorial

Along with the String, the array is the most used data structure in Java. In fact, String is also backed by a character array in Java and other programming languages. It's very important for a Java programmer to have good knowledge of array and how to do common things with array e.g. initialization, searching, sorting, printing array in a meaningful way, comparing array, converting an array to String or ArrayList and doing some advanced slicing and dicing operation with an array in Java. Like my previous tutorials 10 example of HashMap in Java, I'll show you some practical example of array in Java. If you think, any important operation is not included, you can suggest their examples and I'll add them to this list.

Top 5 Amazing Gifts for Programmers, Coders, and Software Developers

If you are planning for a surprise gift to your programmer boyfriend and husband on this holiday season e.g. Black Friday, on Christmas, or New Year or maybe on his next birthday, but not sure what to gift, then you have come to the right place. In this article, I am going to share some of the best gifts every programmer wish for. To be honest with you, buying a gift is easy but finding the right gift is very tough. I have spent countless hours on the internet to find a perfect gift for one of my colleague's husband and this article is a result of that research. The general perception of programmers is that they are a nerd, they love books, gadgets, cool stuff, music, but the perfect gift is something which not only provides the enjoyment but also the value.

Java Enum With Constructor Example

Java Enum with Constructor
Many Java developers don't know that Java Enum can have a constructor to pass data while creating Enum constants. This feature allows you to associate related data together. One example of passing arguments to enum Constructor is our TrafficLight Enum where we pass action to each Enum instance e.g. GREEN is associate with go, RED is associated with stop and ORANGE is associated with the slow down. This is really useful because it provides more context and meaning to your code. If you want, you can also provide one or more constructor to your Enum as it also supports constructor overloading like normal Java classes. This is very different from enum you have seen in C or C++, which is just a collection of fixed thing without any OOP power.

Top 5 Free jQuery Courses for Web Developers - Best of Lot

Hello guys, if you are thinking to learn jQuery and looking for some awesome free resources e.g. books, tutorials, and online courses then you have come to the right place. In this article, I am going to share some of the best free jQuery courses from Udemy and Pluarlsight which you can take to learn this awesome JavaScript library. In the past, I have also shared some free books and tutorials on jQuery, which complements these courses. You can also take a look at then while learning different parts of jQuery.
Before I share these free courses, let me brief you about what jQuery is and why you should learn it? Well, jQuery is a JavaScript library but unlike any other library it is very powerful and makes the client side scripting really easy.

10 Examples of Collectors in Java 8

As the name suggests, Collectors class is used to collect elements of a Stream into Collection. It acts as a bridge between Stream and Collection and you can use it to convert a Stream into different types of Collections e.g. List, Set, Map. Btw, it not just limited to that, it even provides functionalities to join String, group by, partition by and several other reduction operators to return a meaningful result. It's often used along with collect() method of Stream class which accepts a Collectors. In this article, we'll learn Collectors by following some hands-on examples.

How to Implement a Power Function in Java - Coding Interview Problems

Even though the Java library has a power function, Math.pow() to calculate the power of a given number in Java, it's a common programming exercise for Java programmer to implement a power function. If you have used the Math class then you know that the java.lang.Math.pow(double a, double b) returns the value of the first number raised to the power of the second number and you need to do the same. In other words, you need to write a Java function to calculate the power of integer numbers for simplicity. The original method accepts a double value but you are allowed to use just integer but beware that power function may overflow.

Effective Java 3rd Edition by Joshua Bloch – A Must Read Book for Java Developers

Hello guys, you might have heard about it that Effective Java 3rd Edition is finally available. After 10 years of the long wait by Java programmers from all over the world, finally, an updated version of, probably the most popular Java book on the planet is released now. This new version covers the features and paradigm introduced in JDK 7, 8, and 9.  Joshua Bloch has done a great job in also updating most of the items to keep it relevant to the newer version. Apart from that, there is a whole new chapter added to explain best practices around Java 8 features. I know you don't need any reason to read this book, given its huge popularity and acceptance. Many startups which use Java,  particularly in India, are also distributing copies of this book as a New Year Gift.

Java 8 Default Methods FAQ - Frequently asked Questions and Answers

In last a couple of articles, I have to talk about default methods introduced in JDK 8. First, we have learned what is default method and why it is introduced in Java. Then we have seen the example of how you can use default methods to evolve your interface. After that we have analyzed does Java really support multiple inheritances now in JDK 8 (see here) and how will Java handle the diamond problem that will arise due to default methods. For example, what will happen if a class extend a class and implement an interface and both contain a concrete method with same method signature? Will a diamond problem arise? How will Java handle that and how you can solve it, and the difference between abstract class and interface in Java 8?  Once you went through those articles, you would have a good knowledge of default methods in Java 8.

Difference between wait() and join method in Java thread

Though both wait() and join() methods are used to pause the current thread and have a lot of similarities they have different purposes. One of the most obvious differences between the wait() and join() method is that former is declared in java.lang.Object class while join() is declared in java.lang.Thread class. This means that wait() is related to the monitor lock which is held by each instance of an object and join method is related to Thread itself. The wait() method is used in conjunction with notify() and notifyAll() method for inter-thread communication, but join() is used in Java multi-threading to wait until one thread finishes its execution.

Top 10 Java 8 Stream and Functional Programming Interview Questions Answers

The JDK 8 release has changed the way we write Java. With new functional programming idioms and a powerful Stream API, most of the new Java code is written in functional style. This also means that Stream and Functional programming related questions are increasing on Java interviews. If you are not familiar with Java 8 changes then it's difficult to crack a Java interview nowadays. Though it's not stated anywhere most of the companies now expect Java developers to know at least Java 8, which is also good right? Java 11 is already out and we are looking forward to Java 12 in a couple of months, it makes sense to know at least Java 8 changes.  Since more and more of my readers are asking about Java 8 interview questions to me, I have started a series where I take one or two topics and share 15 to 20 interview questions.

Difference between @SpringBootApplication vs @EnableAutoConfiguration annotations in Spring Boot

Even though both @SpringBootApplication and @EnableAutoConfiguration can be used to enable the auto-configuration feature of Spring Boot there is a subtle difference between them. The @SpringBootApplication does much more than what @EnableAutoConfiguration do. It's actually a combination of three annotations: @Configuration which is used in Java-based configuration on Spring framework, @ComponentScan to enable component scanning of components you write e.g. @Controller classes, and @EnableAutoConfgiuration itself, which is used to enable auto-configuration in Spring Boot application. Spring Boot designers realize that these three annotations are frequently used together so they bundled them into @SpringBootApplicaiton. Now, instead of three annotations you just need to specify one annotation on your Main class.

How to use Callable Statement in Java to call Stored Procedure? JDBC Example

The CallableStatement of JDBC API is used to call a stored procedure from Java Program. Calling a stored procedure follows the same pattern as creating PreparedStatment and than executing it. You first need to create a database connection by supplying all the relevant details e.g. database URL, which comprise JDBC protocol and hostname, username, and password. Make sure your JDBC URL is acceptable by JDBC driver you are using to connect to the database. Every database vendor uses different JDBC URL and they have different driver JAR which must be in your classpath before you can run the stored procedure from Java Program.

Top 5 Free React JS Courses for Web Developers to Learn Online

React JS is one of the most popular frameworks or Javascript library for building user interfaces. It's backed by Facebook and it's often viewed as an alternative to the Angular framework by Google. React is also very flexible, fast, easy to learn and fun to work with. It is designed to make the process of building modular, reusable user interface components simple and intuitive and that's why most of the modern GUI and web applications are build using React framework. It is developed at Facebook and focuses on the 'View' aspect of MVC in web applications. React was built for the purpose of developing applications that are large in nature and have to deal with time changing data.  So if you need fast refresh i.e. updating individual component without updating whole DOM then React is the right framework.

10 High Paying Technologies Programmers Can Learn in 2018

Since last a couple of the week, I have been doing some research about what to learn in 2018 when I stumbled about StackOverflow's Developer Survey for 2017. It's one of the best surveys for software developers, which provides useful insights about programming and IT world. One of the things I really like about this survey was its several lists e.g. the list of top 10 programming languages and the most loved frameworks by programmers, but the one I found most useful was the list of top paying technologies. This is a great list and allow you to choose what you can learn in 2018 to go to the next level in your career in terms of both financial and career growth.

A Beginners Guide to Package in Java

If you are learning Java then you might have come across package concept and if you are wondering what is package and why should we use it then you have come to the right place. In this article, I will explain what is package in Java and other stuff around the package, including some best practices which using the package in Java. In the simplest form, a package is a way to organize related functionality or code in single place in Java. If you look from File System perspective then a package in Java just represent a directory where Java source file is stored in compilation and class files are stored after compilation. For example, if you create a class HelloWorld in a package called com.java67.welcome; then it will reside under directory com/java67/welcome in the source tree and you can view that in your IDE like Eclipse or Netbeans or even by navigating to file system.

Java CountDownLatch Example - Multithreading and Concurrency Tutorial

The CountDownLatch is an important concurrency utility class which was added in JDK 1.5 but unfortunately, many Java developers still struggle to understand and use this powerful tool. You can use CountDownLatch if you are spawning multiple threads to do different jobs and want to know when exactly all tasks are finished so that you can move to next stage. In other words, you can block a thread until other threads complete their task. One of the good examples where you can use CountDownLatch is an application which downloads data from a database or another application. For example, we are creating a Java program to download all Udemy courses. Since Udemy has thousands of courses, you create different threads to download different categories e.g. technology, development etc.

5 Free Python Courses for Beginners to Learn Online

Hello guys, If you are a beginner looking for some Free Python resources to start your programming journey then you have come to the right place. Earlier, I have shared a couple of free Python Programming eBooks sand today I'll share a couple of good Python programming courses which are absolutely FREE!! You can take these online courses to learn Python at your own pace, at your own time, and at your place. This is a great advantage of online learning, the flexibility it provides is just awesome.  You just need a laptop or a smartphone with an internet connection and you can learn anything. Btw, before to start with the list of courses to learn Python programming I want to congratulate you for making the right decision to start your programming journey with Python.

Difference between Abstract class and Interface in Java 8

Ever since JDK 8 has allowed concrete (non-abstract) methods on the interface like default and static methods, many of my readers have asked me how should they answer the classical abstract class vs interface questions. Earlier, an interface cannot have any concrete methods and that was the main difference between abstract class and interface but now that is not the case. In this post, I'll revisit this hugely popular Java interview question in light of Java 8 changes. As I said, before JDK 8, the level of abstraction was the clear-cut difference between abstract class and interface i.e. interface was the purest form of abstraction which only defines what interface is supposed to do without specifying how they should be implemented, in other words, it only declares API methods and leaves implementation to its subclasses.

5 Free Ruby and Rails Courses to Learn Online

Hello guys, welcome to this post, here you will find some of the best free courses to learn Ruby programming language and Ruby on Rails framework online. If you don't know what is Ruby and what is Rails framework then let me tell you that its one of the simplest programming language with little to no syntax. If you are new to programming or never coded before then also developing a Ruby application will be much easier than choosing any other programming language like Python or Java. When it comes to developing web development, the Ruby on Rails also makes your job easy by making several useful assumptions based upon convention, which means you can do more by writing less code.

Top 10 Free Java Courses for Beginners and Experienced Programmers

The Internet is full of useful resources and no matter what you want to learn there is something useful available for free. You just need to commit your time and effort. But at the same time, it's difficult to choose in the huge sea of free tutorials and courses on the internet. If you are not careful, you will spend most of your time browsing and changing courses without learning anything. That's where a curated list helps. Curation is my hobby and passion. I love to read books and courses which allows me to curate useful resources and share with you guys.

How to work with Files and Directories in Java

The File API is one of the important parts of any programming language or API and even though Java's file API both new and old, are powerful, they are not intuitive enough compared to other languages e.g. Python. Apart from knowing the essential classes and abstractions e.g. File, InputStream, OutputStream, Reader, Writer, Channel etc, you also need to know and remember some nitty gritty detail to avoid subtle issues. There are many articles out there on the internet which can teach you how to read and write data from the file but there are very few which will tell you to do it in right way.

How to implement Radix Sort in Java - Algorithm Example

The radix sort, like counting sort and bucket sort, is an integer based algorithm (i.e. the values of the input array are assumed to be integers). Hence radix sort is among the fastest sorting algorithms around, in theory. It is also one of the few O(n) sorting algorithm along with a bucket and counting sort. The particular distinction for radix sort is that it creates a bucket for each cipher (i.e. digit); as such, similar to bucket sort, each bucket in radix sort must be a growable list that may admit different keys.

Top 5 Free R Programming Courses for Data Scientists and ML Programmers

More and more people are learning R programming language to become a Data Scientist, one of the hottest and high paying technical jobs on the planet. Though, I am from Python camp when it comes on choosing between Python and R for Data Science, Machine Learning, and Artificial Intelligence, mainly because of the awesome libraries Python offers, I had tried R for a short time. If you are also on the same boat and want to try or learn R programming for Data Science and machine learning purpose and looking for some awesome free courses to start your journey then you can take some ideas from this article.

How to convert primitive int value to a Long object in Java?

Suppose you have an int variable but the part of the application is expecting a Long object, how do you convert a primitive int to a Long object in Java? It shouldn't be a problem, right? after all long is a bigger data type than int, so all int values are acceptable as long, but we also need a Long object, not just the long primitive value. Now, the problem is reduced to converting a long primitive to Long object, which is not really a problem if you are running on JRE version higher than Java 5. But, sometimes autoboxing is not efficient e.g. when you have to convert multiple long values into the Long object in a loop. A better way to convert your long primitive to the Long object is by using static factory methods like Long.valueOf(long l), which was originally meant to convert long primitive values to a Long object, prior to Java 5, but, also works fine with int primitive.

Top 10 Data Science and Machine Learning Certification Courses to Learn Online - Best of Lot

If you work in the technology field today like you are a programmer or software engineer then I am sure you have heard about terms like Data Science, Machine Learning, Deep Learning, Artificial Intelligence etc. They are the latest technologies which are impacting every single sector just like IT does it when it comes the first time. It doesn't matter if you are working for a bank or insurance sector, airspace or defense, all fields were impacted by IT and in near future, they will be impacted by machine learning and artificial intelligence. If you are wondering, let me give you a brief overview. Machine learning is all about training machines to do the job which was only possible by humans before, for example seeing a photo and recognizing what is the object like a car, a human or a cucumber.