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- Core Java Multiple Choice Questions With Answers 2021
- Core Java MCQ Questions – Java Online Challenge
- Java Multiple Choice Questions and Answers
Core Java Multiple Choice Questions With Answers 2021
Download PDF We have compiled the most frequently asked Java Interview Questions and Answers that will help you prepare for the Basic Java interview questions that an interviewer might ask you during your interview. In this list of Basic Java interview questions, we have covered all commonly asked basic and advanced Core Java interview questions with detailed answers to help you clear the job interview. The following list contains important Core Java interview questions for freshers as well as Java interview questions and answers for experienced programmers to help them prepare for the interview.
This detailed guide of interview questions for Java Programming will help you to crack your Job interview easily. What is the difference between an Inner Class and a Sub-Class?
Ans: An Inner class is a class which is nested within another class. An Inner class has access rights for the class which is nesting it and it can access all variables and methods defined in the outer class.
A sub-class is a class which inherits from another class called super class. Sub-class can access all public and protected methods and fields of its super class. What are the various access specifiers for Java classes? Ans: In Java, access specifiers are the keywords used before a class name which defines the access scope. The types of access specifiers for classes are: 1.
Public : Class,Method,Field is accessible from anywhere. Protected:Method,Field can be accessed from the same class to which they belong or from the sub-classes,and from the class of same package,but not from outside. Default: Method,Field,class can be accessed only from the same package and not from outside of it's native package. Private: Method,Field can be accessed from the same class to which they belong. What's the purpose of Static methods and static variables?
Ans: When there is a requirement to share a method or a variable between multiple objects of a class instead of creating separate copies for each object, we use static keyword to make a method or variable shared for all objects.
What is data encapsulation and what's its significance? Ans: Encapsulation is a concept in Object Oriented Programming for combining properties and methods in a single unit. Encapsulation helps programmers to follow a modular approach for software development as each object has its own set of methods and variables and serves its functions independent of other objects.
Encapsulation also serves data hiding purpose. What is a singleton class? Give a practical example of its usage. A singleton class in java can have only one instance and hence all its methods and variables belong to just one instance.
Singleton class concept is useful for the situations when there is a need to limit the number of objects for a class. The best example of singleton usage scenario is when there is a limit of having only one connection to a database due to some driver limitations or because of any licensing issues.
What are Loops in Java? What are three types of loops? Ans: Looping is used in programming to execute a statement or a block of statement repeatedly. There are three types of loops in Java : 1 For Loops For loops are used in java to execute statements repeatedly for a given number of times. For loops are used when number of times to execute the statements is known to programmer.
In while loops, condition is checked first before execution of statements. Hence in case of do while loop, statements are executed at least once. Q7: What is an infinite Loop? How infinite loop is declared? Ans: An infinite loop runs without any condition and runs infinitely. An infinite loop can be broken by defining any breaking logic in the body of the statement blocks.
What is the difference between continue and break statement? Ans: break and continue are two important keywords used in Loops. When a break keyword is used in a loop, loop is broken instantly while when continue keyword is used, current iteration is broken and loop continues with next iteration.
In below example, Loop is broken when counter reaches 4. What is the difference between double and float variables in Java? Ans: In java, float takes 4 bytes in memory while Double takes 8 bytes in memory. Float is single precision floating point decimal number while Double is double precision decimal number. What is Final Keyword in Java?
Give an example. Ans: In java, a constant is declared using the keyword Final. Value can be assigned only once and after assignment, value of a constant can't be changed.
This method are faster than any other method,because they are resolved at complied time. When a class is declares as final,it cannot be subclassed. Example String,Integer and other wrapper classes. What is ternary operator? Ans: Ternary operator , also called conditional operator is used to decide which value to assign to a variable based on a Boolean value evaluation. It's denoted as? In the below example, if rank is 1, status is assigned a value of "Done" else "Pending".
Ans: Using Math. What is default switch case? Give example. Ans: In a switch statement , default case is executed when no other switch condition matches. Default case is an optional case. It can be declared only once all other switch cases have been coded. In the below example, when score is not 1 or 2, default case is used. What's the base class in Java from which all classes are derived? Ans: java. Can main method in Java can return any data? Ans: In java, main method can't return any data and hence, it's always declared with a void return type.
What are Java Packages? What's the significance of packages? Ans: In Java, package is a collection of classes and interfaces which are bundled together as they are related to each other. Use of packages helps developers to modularize the code and group the code for proper re-use. Once code has been packaged in Packages, it can be imported in other classes and used.
Can we declare a class as Abstract without having any abstract method? Ans: Yes we can create an abstract class by using abstract keyword before class name even if it doesn't have any abstract method. However, if a class has even one abstract method, it must be declared as abstract otherwise it will give an error. What's the difference between an Abstract Class and Interface in Java? Ans: The primary difference between an abstract class and interface is that an interface can only possess declaration of public static methods with no concrete implementation while an abstract class can have members with any access specifiers public, private etc with or without concrete implementation.
Another key difference in the use of abstract classes and interfaces is that a class which implements an interface must implement all the methods of the interface while a class which inherits from an abstract class doesn't require implementation of all the methods of its super class. A class can implement multiple interfaces but it can extend only one abstract class.
What are the performance implications of Interfaces over abstract classes? Ans: Interfaces are slower in performance as compared to abstract classes as extra indirections are required for interfaces. Another key factor for developers to take into consideration is that any class can extend only one abstract class while a class can implement many interfaces.
Use of interfaces also puts an extra burden on the developers as any time an interface is implemented in a class; developer is forced to implement each and every method of interface. Does Importing a package imports its sub-packages as well in Java? Ans: In java, when a package is imported, its sub-packages aren't imported and developer needs to import them separately if required.
For example, if a developer imports a package university. To load the classes from its sub-package say department , developer has to import it explicitly as follows: Import university. Can we declare the main method of our class as private?
Ans: In java, main method must be public static in order to run any application correctly. If main method is declared as private, developer won't get any compilation error however, it will not get executed and will give a runtime error. How can we pass argument to a function by reference instead of pass by value? Ans: In java, we can pass argument to a function only by value and not by reference. How an object is serialized in java?
Ans: In java, to convert an object into byte stream by serialization, an interface with the name Serializable is implemented by the class. All objects of a class implementing serializable interface get serialized and their state is saved in byte stream. When we should use serialization? Ans: Serialization is used when data needs to be transmitted over the network.
Using serialization, object's state is saved and converted into byte stream. The byte stream is transferred over the network and the object is re-created at destination.
Core Java MCQ Questions – Java Online Challenge
Explanation: The output of the Java compiler is bytecode, which leads to the security and portability of the Java code. It is a highly developed set of instructions that are designed to be executed by the Java runtime system known as Java Virtual Machine JVM. The Java programs executed by the JVM that makes the code portable and secure. Because JVM prevents the code from generating its side effects. The Java code is portable, as the same byte code can run on any platform. Explanation: The Java language does not support pointers; some of the major reasons are listed below:.
These section include questions with answers on basic theory of Java to test knowledge of fundamental concept of Java programming language. If you are going to apply for an entry-level positions in Java related job , then you are not expected to answer the tricky java interview questions , rather you should have solid understating of Java basics - the fundamental concept and feature of Java as object oriented programming language. These Java mcq sets will get you acquainted with the nature of questions you may encounter during your Java interview or competitive exams for popular programming language Java related career. Here you will find a list of common important questions on java programming in MCQ quiz style with answer for competitive exams and interviews. These frequently asked sample questions on Java are given with correct choice of answer that you can check instantly. Presently we have added total 5 sets of questions on java programming for you to practice. We will keep adding more questions and provide this question bank in PDF format, so that you can download them instantly in E-book style.
These multiple choice questions(MCQs) on Java Programming (25+ We will keep adding more questions and provide this question bank in PDF format.
Java Multiple Choice Questions and Answers
Which one of the following is true for Java A Java is object-oriented and interpreted B Java is efficient and faster than C C Java is the choice of everyone. D Java is not robust. The command javac is used to A debug a java program B compile a java program C interpret a java program D execute a java program.
Download PDF We have compiled the most frequently asked Java Interview Questions and Answers that will help you prepare for the Basic Java interview questions that an interviewer might ask you during your interview. In this list of Basic Java interview questions, we have covered all commonly asked basic and advanced Core Java interview questions with detailed answers to help you clear the job interview. The following list contains important Core Java interview questions for freshers as well as Java interview questions and answers for experienced programmers to help them prepare for the interview. This detailed guide of interview questions for Java Programming will help you to crack your Job interview easily. What is the difference between an Inner Class and a Sub-Class?
JAVA Questions and Answers has been designed with a special intention of helping students and professionals preparing for various Certification Exams and Job Interviews. This section provides a useful collection of sample Interview Questions and Multiple Choice Questions MCQs and their answers with appropriate explanations.
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