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How to Remove Entry (key/value) from HashMap while Iterating? Example Tutorial

Can you remove a key while iterating over HashMap in Java? This is one of the interesting interview questions as well as a common problem Java developer face while writing code using HashMap. Some programmer will say No, you cannot remove elements from HashMap while iterating over it. This will fail fast and throw concurrent modification exception. They are right but not completely. It's true that the iterator of HashMap is a fail-fast iterator but you can still remove elements from HashMap while iterating by using Iterator's remove() method. This is the same technique which we have used in past to remove elements while iterating over a List in Java. The key here is not to use the remove() method from Map or List interface to avoid java.util.ConcurrentModfiicationException in Java.

Top 40 Advanced Java/J2EE Interview Questions Answers for Experienced - 3 to 5 Years

I have shared many posts about Java interview question in the past but nothing, particularly for support engineer perspective. Since there are a lot of L1 and L2 support job exists in BFSI (Banking, Finance, and Insurance Industry) and they are also for the longer term, I decided to write this post. When you go for a support engineer role, especially for Java application be it to core Java or Java EE application, Interviewer expects you know basics of Java and can start/stop the application, see log files, alert developers, and other aspects of the support e.g. opening conference bridge to solve production issues, communicating to stakeholders, and involving right peoples. In this article, I will share questions to help with technical aspects e.g. the essential skills you need to clear a support engineer interview.

99 Angular JS Interview Questions for JavaScript Web Developers

The AngularJS is one of the popular JavaScript frameworks, I think most popular after jQuery, with the core goal of simplification. It allows building dynamic, single page web apps (SPAs) using JavaScript and supports the Model View Controller (MVC) programming structure. It has used widely and even big companies like Google, Virgin America, and HBO are using Angular JS to build their site. The demand for web developers is on all time high and there is a huge demand for developers who understand modern JavaScript frameworks e.g. Angular JS, jQuery, Facebook's React JS etc. The Angular JS is Open-source, front-end JavaScript framework which is developed by Google, it mainly competes with Facebook's ReactJS framework.

How to convert String to char in Java? Example

Earlier, we have seen how to convert a character to String in Java and today we'll learn opposite i.e. converting String to a character. Suppose, you have a String with value "s", how do you convert that to a char 's' in Java (FYI, string literal are quoted inside double quotes in Java e.g. "c" and character literals are quoted inside single quotes e.g. 'c' in J)? Well, if you know, Java String is made of a character array and java.lang.String class provides a method toCharArray() to retrieve that character array. If your String contains just one character then, the only element in character array is what you are looking after. Though that's not the only way to convert a String to char in Java.

Difference between Correlated and Non-Correlated Subquery in SQL

The correlated subquery is one of the tricky concepts of SQL. It's similar to recursion in programming which many programmers struggle to understand, but like recursion, it also offers the unique capability to solve many SQL query based problems e.g. second highest salary problem where you need to compare one row of the table to another row. It gives you a different kind of power. The main difference between a regular, non-correlated and correlated subquery in SQL is in their working, a regular subquery just run once and return a value or a set of values which is used by outer query, but correlated subquery runs for each row returned by the outer query because the output of the whole query is based upon comparing the data returned by one row to the all other rows of the table. That's why it is also very slow and generally avoided until you don't know any other way to solve the problem.

10 points about final modifier in Java

Here are some important details about final modifier in Java:

1) The final is a modifier in Java, which can be applied to a variable, a method or a class.

2) When a final modifier is used with a class then the class cannot be extended further. This is one way to protect your class from being subclassed and often sensitive classes are made final due to security reason. This is also one of the reasons why String and wrapper classes are final in Java.

3) When the final keyword is used with a method that it cannot be overridden in Java, which means you cannot override the logic of the method in the subclass. This is also done to protect the original logic of method.