When to use intern() method of String in Java?

The String.intern() method can be used to deal with the String duplication problem in Java. By carefully using the intern() means you can save a lot of heap memory consumed by duplicate String objects. A String object is said to be duplicate if it contains the same content as another string but occupied different memory location e.g. str1 != str2 but str1.equals(str2) is true. Since the String object consumes a large amount of heap memory in the average Java application, it makes sense to use the intern() method to reduce duplication and take advantage of the String pool feature provided by Java. You can use the intern() method to intern a String object and store them into the String pool for further reuse.

How to use EXISTS Clause in SQL? A Real World SQL Query Example using EXISTS

Hello Guys, you might have heard about how useful the EXISTS clause is helpful in writing sophisticated queries. Still, at the same time, I have also seen that many programmers struggle to understand and use EXISTS and NOT EXISTS clause while writing SQL queries.  If you are one of them, then you have come to the right place. Today you will learn how to use the EXISTS clause in SQL by picking up a real-world example and an excellent SQL exercise from the LeetCode. Suppose that a website contains two tables, the Customers table, and the Orders table. Can you write an SQL query to find all customers who have never ordered anything?

What is the best Book to Learn Java for C and C++ Programmer?

In the last 2 decades, many Java programmers started programming with C and C++, but the situation is changed now, you have more choices like you can choose Python, or you can even start with Java. It seems Academia prefers Python in the USA and Java in India, but there are still many programmers who know C and C++ and want to learn Java for one or other reasons. I often receive emails from my readers about book recommendation, and recently, a couple of them asked me to suggest the best Java books for C and C++ programmers. I can relate those beginners to myself because I have also gone through the same phase, but those days, the university textbooks are our only source to learn new things. We didn't have broadband, and unlimited access to the Internet and eBooks was not popular at that time, but things have changed.

What is a Functional interface in Java 8? @FunctionalInterface Annotation Examples Tutorial

The Functional interface is one of the most important concepts of Java 8 which actually powers lambda expression but many developers don't put enough effort to understand it and spend time learning lambda expression and Stream API without first understanding the role of the functional interface in Java 8. Unless you know what is a functional interface and how lambda is related to it, you can't use powerful features of Java 8 like Lambda expression and Stream API. Without knowledge of functional interface, you won't be able to understand where you can use a lambda in the code but also you will struggle to write lambda expression the method is expecting, hence, it's important to have a good understanding of functional interface in Java 8.

How to Convert a Lambda Expression to Method Reference in Java 8?

If you have been coding in Java 8 then you may know that using method reference in place of lambda expression makes your code more readable, hence it is advised to replace lambda expression with method reference wherever possible. But, the big question is, how do you find whether you can replace a lambda with method reference? Yes, it's not that easy, especially if you have been using Java 8 only for a couple of months and struggling to get the functional programming concepts and idioms sorted in your head. Sometimes, IDEs like IntelliJ IDEA and Eclipse does offer some hints to convert lambda expression to method reference but it does make sense to learn the logic behind it, otherwise, it won't make sense.

The OCAJP 1Z0-808 - Best Books and Mock Exams for Java 8 OCA Certification

From the last couple of months, I have been helping a few developers to prepare for Java 8 associate certification with exam code 1Z0-808, also known as OCAJP 8. From my experience, both for preparing for Sun certification and helping other developers to get Java certified, I can say that two keys to be successful in Oracle Java SE certification are choosing an excellent study guide/course and buying one or two top quality mock exam simulators. When I say success, it doesn't mean just passing the exam but scoring above 90% because passing score 65% is not very difficult to achieve and anybody can pass OCAJP 8 by just a couple of month of practice but to score 90% and above is not that easy, you need to prepare and prepare hard.

How to Compare Date in SQL Server Query? Finding All Rows Between Two Dates

It's tricky to use dates in the SQL server query, especially if you don't have good knowledge of how DateTime type works in the SQL server. For example, one of the frequently asked SQL queries on the interview is to "select all rows where the date is 20151007?" How would you do that? Does the following SQL Query will work correctly

select * from table where date = '20151007'

It may or may not, it entirely depends on upon data in your table. When you only provide date part of a DateTime variable, it uses '00:00:00.000' for the time part.