Core Java interview

Armstrong number is a 3 digit number which is equal to sum of cube of its digits. For example: 371,153 In this post,  we will see how to check for Armstrong number in java. [crayon-69f04dadaf8bc180693396/] When you run above program, you will get following output. [crayon-69f04dadaf8c4119510961/] Please go through Frequently asked java interview Programs for more such […]

You might have noticed Object class has three final method called wait, notify and notifyAll. These methods are used for inter thread communication.  Java 5 has introduced executor framework which takes care of inter thread communication for you and internally uses wait, notify and notifyAll but you still require basic understanding of these methods and […]

One of the common interview question is “What is difference between ArrayList and LinkedList”.Before we actually see differences,let me give you brief introduction of both. ArrayList ArrayList is implementation of list interface. ArrayList is not synchonized(so not thread safe) ArrayList is implemented using array as internal data structure.It can be dynamically resized . LinkedList LinkedList […]

In this post, we will see about Java thread join method. Thread class’s join() method can be used to stop current execution of thread until thread it joins, completes its task. So basically, it waits for the thread on which join method is getting called, to die.For example: Here when you call t1.join(), main thread […]

Sleep method of java.lang.Thread is used to pause current execution of thread for specific period of time. Some important points about sleep method are : It causes current executing thread to sleep for specific amount of time. Its accuracy depends on system timers and schedulers. It keeps the monitors it has acquired, so if it […]

Thread can be called as light weight process. Java supports multithreading , so it allows your application to perform two or more task concurrently.  Multithreading can be of advantage specially when now a days, machine has multiple CPUs, so multiple tasks can be executed concurrently. Whenever we call main method in java, it actually creates […]

In this post, we will see about Hashset in java Java HashSet: [crayon-69f04dadb2751784837101/] This is one of the frequently asked question in core java interview so in this post, we will see how HashSet works in java.We have already seen How hashMap works in java and also difference between HashMap and HashSet. Lets first see […]

One of the common interview question is “What is difference between sleep and wait in java”.Before we actually see differences,let me give you brief introduction of both. sleep It causes current executing thread to sleep for specific amount of time. Its accuracy depends on system timers and schedulers. It keeps the monitors it has acquired, […]

This is easy question. It may not be asked you directly, but you can use this program to create many other complex program. A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Program logic: If any number which is not divisible by any other […]