Top 50 Java Programming Interview Questions

That’s why it’s better to have null check in place for early validation. We can run the shuffling code inside another for loop to shuffle multiple rounds. We can use Character.isWhitespace() method to remove whitespaces from the string.

It is used for runtime polymorphism and to implement the interface methods. Yes, It is possible to use this keyword to refer static members because this is just a reference variable which refers to the current class object. However, as we know that, it is unnecessary to access static variables through objects, therefore, it is not the best practice to use this to refer static members. The Object is the real-time entity having some state and behavior. In Java, Object is an instance of the class having the instance variables as the state of the object and the methods as the behavior of the object.

Q 80. Identify the output of the below Java program and Justify your answer.

Asking the candidate to enumerate and expound on the common features of Java programming language helps examine the range of their knowledge. This question is most commonly asked to Java developers with more than three years of experience. Through this straightforward question, you can probe the applicant’s technical knowledge. Also, this question helps get to know the candidate better, whether they are an eager learner or a stagnant developer. Both methods serve as a hint to the JVM to start a garbage collection. However, it’s up to the JVM to start the collection right away or later. HashMap is constructed using the hash table data structure.

JDK has tools that are required to write Java Programs and uses JRE to execute them. It has a compiler, Java application launcher, and an applet viewer. An Exception handling in Java is considered an unexpected event that can disrupt the program’s normal flow. These events can be fixed through the process of Exception Handling. Neither the Local Variables nor any primitives and Object references have any default value stored in them. A classloader in Java is a subsystem of Java Virtual Machine, dedicated to loading class files when a program is executed; ClassLoader is the first to load the executable file. In Java, the source code is the compiled output is a platform-independent byte code.

Question 15 : Find the number occurring odd number of times in an array

Composition is again a specialized form of Aggregation and we can call this as a “death” relationship. Child object does not have their lifecycle and if parent object deletes all child object will also be deleted. Let’s take again an example of a relationship between House and rooms. House can contain multiple rooms there is no independent life of room and any room can not belongs to two different houses if we delete the house room will automatically delete. If a child class inherits the property from multiple classes is known as multiple inheritance. In Method Overloading, Methods of the same class shares the same name but each method must have a different number of parameters or parameters having different types and order.

• Moreover, since JVM is responsible for implicit memory allocation, thus in order to avoid direct access to memory by the user, pointers are discouraged in Java.
• That’s why this tutorial might benefit you a lot, at least giving you the core directions to recall from your personal database.
• Singleton class control object creation, limiting the number to one but allowing the flexibility to create more objects if the situation changes.
• We can use Scanner class to read the file contents line by line.
• You need to write push and pop methods to demonstrate Stack behavior.

Generic methods and classes help programmers specify a single method declaration, a set of related methods, or related types with an available class declaration. A collection of how to become a java developer strings in Java’s Heap memory is referred to as Java String Pool. In case you try to create a new string object, JVM first checks for the presence of the object in the pool.