Most Commonly Asked Java Interview Questions

Java is an object-oriented programming language. For Android development, it is the most widely used programming language. It may also be used to develop desktop applications, web applications, and web services. As a consequence, we've put up a list of the most important Java Interview Questions you'll need to answer in order to obtain your dream IT job.

1.Is it possible to revive a dormant thread?

ANS:In Java, a thread that has reached the end of its life cycle cannot be restarted. A thread cannot be restarted in any way.

2.What sorts of exceptions are captured at build time?

ANS:Checked exceptions can be caught during the compilation of a programme. To build the code properly, checked exceptions must be handled via a try catch block.

3.Is it possible to utilise a class's default function Object() { [native code] } even if an explicit function Object() { [native code] } is defined?

ANS:If no explicit function Object() { [native code] } has been provided in a Java class, Java provides a default no argument function Object() { [native code] }. However, if an explicit function Object() { [native code] } is specified, the default function Object() { [native code] } is disabled, and the developer may only use the constructors described in the class.

4.Is it possible to override a method with the same name and parameters but distinct return types?

ANS:The primary criteria for method overriding is that the method parameters, name, and return type must be identical to the method being overridden. As a result, overriding a method with a different return type is not possible.

5.Is it possible to invoke a non-static method from within a static method?

ANS:To invoke non-static methods from a static block, a class object must first be generated. Non-static methods are owned by objects of a class and have object level scope. These methods can then be called using an object reference.

6.Mention the two environment variables that must be set before any Java programme can be run.

ANS:It's one of the most popular Java Interview Questions that's been asked in the past. Only if the two environment variables are properly configured can Java applications be implemented in a machine: variable PATH variable CLASSPATH Is it possible to utilise a variable in Java without first initialising it?

Because no default value is assigned to variables in Java, when a variable is utilised in a code without prior initialization by a valid value, the programme does not compile and produces an error.

7.In Java, may a function Object() { [native code] } have a different name than the class name?

ANS:In Java, the function Object() { [native code] } should have a name that is comparable to the class name; otherwise, it will not work as a function Object() { [native code] }, and the compiler will treat it as a regular method.

8.What will the outputs of Round(3.7) and Ceil(3.7) be?

ANS:Round(3.7) and Ceil(3.7) both return 4.

9.Is it possible for a Java class to inherit from several classes?

ANS:In Java, a class can only be derived from one other class, not from many classes. Java does not allow multiple inheritances.

10.Is it possible to use goto in Java to go to a specific line?

ANS:There is no goto keyword in Java, and the capability of moving to a specific labelled line is not supported.

11.Is it possible to revive a dormant thread?

ANS:In Java, a thread that has reached the end of its life cycle cannot be restarted. A thread cannot be restarted in any way.

12.Is the Java Development Kit (JDK) required on each workstation to run a Java programme?

ANS:JDK stands for Java Development Kit, and it is just required for development. It is not required to run a Java application on a system. However, just the Java Runtime Environment (JRE) is necessary.

13.Is it feasible to specify a method in a Java class but implement it in a different language, such as C?

ANS:Yes, we can use native techniques to do this. In native method oriented programming, we write public static methods in our Java class without executing them, and then we execute them independently in another language like C.

14.Is it possible for a variable to be both static and local at the same time?

ANS:No, it's not feasible; a variable cannot be both static and local at the same time. A compilation error occurs when a local variable is declared as static.

15.Is it possible to have static methods in an interface?

ANS:When any methods in an interface are by default abstract, which is expected to be implemented in the classes executing the interface, static methods cannot be modified in any of the classes. As a result, it's pointless to include static methods in an interface in Java.

16.In Java, how are destructors defined?

ANS:There are no destructors declared in Java classes since they are not required. Java has its own garbage collection system that handles the work for you by removing things that are no longer in use.

17.Is it true that a Java application never runs out of memory because of Java's garbage collection feature?

ANS:It does not guarantee that a Java application will not run out of memory, but Java provides automated garbage collection since there is a chance that java objects are created at a faster rate than garbage collection, resulting in the use of all available memory resources. As a result, trash collection aids in reducing the likelihood of the application running out of memory, but it does not guarantee it.

18.Is it possible to modify the value of any interface variable in a class that implements an interface?

ANS:No, we can't modify the value of any interface variable in the implementing class since all interface variables are by default static, public, Final, and final variables, which are identical to constants that can't be modified afterwards. These are what we have to give you.

19.In Java, how are destructors defined?

ANS:There are no destructors declared in Java classes since they are not required. Java has its own garbage collection system that handles the work for you by removing things that are no longer in use.

20.Is it true that a Java application never runs out of memory because of Java's garbage collection feature?

ANS:It does not guarantee that a Java application will not run out of memory, but Java provides automated garbage collection since there is a chance that java objects are created at a faster rate than garbage collection, resulting in the use of all available memory resources. As a result, trash collection aids in reducing the likelihood of the application running out of memory, but it does not guarantee it.

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