100+ Java Interview Questions You Must Prepare In 2021

At the beginning of the years, JavaScript had taken the market in the popular programming language. It is very used to make websites on the Internet. JavaScript is used, all the popularity of the world has increased a lot from the date. The purpose of using JavaScript is different from one and another JavaScript is also used to create cookies by undertaking browsers. Completing courses in JavaScript I am and professional in JavaScript language helps develop and maintain dynamic web pages that are very popular in the digital market. Now, JavaScript has been compatible with Google Chrome Microsoft Edge Mozilla Firefox Safari and Internet Explorer and other browsers as well. Java scripts are for beginners, but today, most programmers are using JavaScript, since it is very suitable and programming it becomes much easier than other programming languages. 

Coding on the JavaScript page Just like playing games in childhood Once a person understands the programming code, then we can make the website very easily. Java is one of the cross platform object oriented programming language and it was originated by the organisation in the year 1995. In the current programming java is essential to run different games, social media application, audio and the video application. Java has been developed by James Gosling with other team support. Java interview questions are very much helpful in the career also. 


1. Explain Public Static Void Main (String args) in java.

Ans: Main() in Java is the first entry point which is the entry point for any java program. It is mandatorily written in void main (String[] args).

Public: Public is an access modifier, which is used to specify who was the last user had access this method. Public means that this method will be accessible by any of the user. 

Static: It is a keyword in java which identifies it is in a class-based. Main() is made static in the java so that it can be accessed without the creation for the instance of any classs. In this case the main program is not made in the static manner and it can be compiled afterwards. The main problems arises as the JVM of any objects are made and the static methods can be easily directed through the class. 

Void: It is the type of the method which used to get back or the return. Void is defined as the function which will not return any of the value.

Main: The name of this method which is researched by JVM as a starting point for an execution with the use of any other application. It is mainly used in the process of huge data transfer.

2. Why java is platform independent?

Ans: Java is called platform which is independent because of the byte codes which can run on any of the system which doesn’t requires any of the particular specification. It is underlying operation system which helps to get the application done properly. 

3. Why java is not 100% Object- oriented?

Ans: Java is not 100% Object oriented because the reason behind it that it makes the use of different data types and they are very much important in this. Those data types are Boolean, Byte, char, int, float, double, long, short and these all not objects. So, it the main reason why it is some not coming under the 100% Object-orientated. 

4. What are wrapper classes in Java?

Ans: Wrapper classes convert the Java primitives into the reference types (Objects). Every small and essential data are linked with it. The large data are formed by the small ones and it can be found at any of the file in the large one. It is referred as the wrap one since it wrap the large files into the small ones. 

5. What are the different types of constructor which are used in Java?

Ans: In Java, constructor is known to block of code which is used in the starting of the codes. Then the main file is changed in the new one as it is not required any more. There are two different types of Construtors:

1. Default constructor: Default constructor is the one which takes the input from the user and doesn’t let the user to take any more changes in it. If the user puts some of the fault codes then it will make into the normal ones. The main purpose is to initialize the instance variable with the real ones. It is used mostly in the Object creation. 

2. Parameterized Constructor: The parameterised constructor tool is used to take away the main data into the input section and initialize the process the further action.

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