Java Interview Questions (Part-2) | Read Now

Java Interview Questions (Part-2) will contain some more core previously asked questions by the interviewers in internships or jobs that can help you pass your test.

21] Can you implement any piece of written code before the main method?

Yes, we can perform that task by utilizing the static code block.

22] What types of polymorphism exist in Java? Briefly elaborate on them.

In Java, Polymorphism is of two types. They are run-time and compile-time.

Run-time: The run-time polymorphism calls the method that is overridden at run time. Also known as late/dynamic binding. It takes more time to be executed and is more adjustable.

Compile-time: The compile-time polymorphism calls the method that is overridden at compile time. Also known as early/static binding. It takes less time to be executed and is less adjustable.

23] Can you define a “platform” in Java?

A platform is the software/hardware infrastructure in which a set of instructions is deployed. There are two sorts of platforms: software platforms and hardware platforms. Java is available in the software relied platform.

24] What procedure does Java utilize for its high performances?

Java has the capability of accurate performance due to the JIT-Just in Time compiler. JIT basically transforms the directions to its matching bytecodes.

25] Can you point out some merits of packages in Java?

• Packages restrict identifiers from clashing.
• The package allows for effective data access.
• We’ll also have the package’s secret class, which aren’t viewable externally.
• It’s pretty easy to find the related classes.

26] Can you list the unique access modifiers in Java?

Yes, Java programming solely contains four sorts of accessibility modifiers and they are as mentioned:

1. Public modifier: It means one can globally access the public defined classes, variables or any methods.
2. Private modifier: It means one can only have the access to a class, variable or method within the defined area.
3. Protected modifier: It means one can have access to a class, variable or method in the similar package or under the similar class.
4. Default modifier: It means one can have access to a class, variable or method just within the defined package and not out of that package.

27] In what ways you can achieve overloading in Java computer language?

Method overloading is a polymorphism strategy that promotes the creation of multiple procedures with similar names but distinct identities. There are two means of achieving procedure overloading:

• Alteration to the number of calls
• Altering the type of gain
• Increasing the set of techniques in a software enhances its usefulness. To quickly figure out the framework, method overloading is often used

28] Can you define the operator namely “instanceOf”?

The “instanceOf” operator is referred to as an operator that is a sort of type comparison because it compares the instances in Java with their own types. It lastly returns the Boolean values that are True or False. Refer to the following illustration:

class demo{  
 public static void main(String args[]){  
 demo d=new demo();  
 System.out.println(d instanceof demo); //true  
 }  
} 

29] What one can understand by the name “Abstraction” in the Java computer language?

Abstraction methodology in Java is the procedure in which the in-depth details of a code are stored secretive and only the functionalities are being shown to the user. It is more like showing the output of a successful game without revealing its strategy.

30] Do you know the default value of data type namely “byte”?

Yes, the default value for data type “byte” is 0.

31] What does the interface in Java computer language mean?

The interface is the key to gaining abstraction. That means it is the blueprint of a class that contains abstract methodologies with static constants. Only abstraction methodologies are allowed in the interface. The methodology body is totally restricted.

32] Are you capable of building up a class that is read-only?

Yes, class read-only can be constructed by making all the fields inside it “private”. The user won’t be able to modify the method, instead can only see it and have an idea of what is written in it.

33] Can you restrict inheritance for some defined class?

Yes, one can achieve that case if implemented the following ideas:

1. Utilize the keyword “final” to not override methods.
2. Utilize the private defined constructors
3. Utilize the comments of JAVA doc that are illustrated as “//”.

34] Can you import packages thrice or multiple times?

Yes, one can import the preferred packages at the time he/she wants to. No run-time or compile-time errors are displayed.

35] Can you elaborate on a class singleton in Java computer language?

Class singleton is the defined class that possesses the feature of the creation of only 1 instance at a preferred time in 1 Java Virtual Machine-JVM. Class singleton can be gained by building up a private constructor.

36] What is the meaning of handling an exception?

Handling an exception is the primary key to resolving the run-time obstacles/errors. The central aim behind handling exceptions is to preserve the normal workflow of a code. This strategy to handle exceptions occurs with “unchecked obstacles/errors”. “Throwable” is the super/base/parent class for exceptions and its followed errors.

37] What does the concept of “exception propagation” refer to?

“Exception propagation” represents the key to catching an exception in the flow of stacks if not caught in the previous stacks. In a simpler sentence, if an exception is not caught in one stack then it’ll be dropped down to another stack and the procedure will carry on until that exception will be finally caught.

38] What comes to your mind with the word “Immutable”?

Immutable primarily mean the denial of change. That is, no change or alteration can be done in an immutable string if it’s once declared and then implemented.

39] Can you accurately guess the number of objects built in the following code?

String s1="VTUloop";  
String s2="VTUloop";  
String s3="VTUloop";  

Here, only one object will be constructed as Java’s strings have the uniqueness of Immutability.

40] What is the exact explanation for “Nested classes”?

In Java computer language, Nested classes refers to the classes that re built under or within a child or parent class. It is done to enhance the readability of a script and to maintain it in a better way.