Generally, technical interviews are conducted to assess candidates for technical or specialist job positions. These interviews test your field-specific technical knowledge. You need to be well-versed with the basic knowledge of Core JAVA.
List of Technical Questions based on Core JAVA
What is the most important feature of Java?
Explain platform independence
What is a JVM?
Are JVMs platform independent?
Differentiate between a JDK and a JVM?
What is a pointer? Does Java support pointers?
Name the base class of all classes
Is multiple inheritance supported by Java?
Is Java a purely object oriented language?
What are primitive data types in Arrays?
What is the difference between a Path and a Classpath?
What are local variables?
What are instance variables?
In Java, how is a constant variable defined?
Is it compulsory to use a main() method in all java classes?
What is the return type of the main() method?
What is the reason behind declaring the main() method static?
What is the argument of main() method?
Can we overload a main() method?
Can we declare a main() method final?
Does the order of public and static declaration matter in main() method?
Can a source file contain more than one class declaration?
What is a package?
Which package is imported by default?
Can a class that has been declared as private be accessed outside its package?
Can a class be declared as protected?
Elaborate the access scope of a protected method?
Elaborate the purpose of declaring a variable as final?
Explain impact of declaring a method as final?
If we do not want our class to be inherited by any other class what should we do?
Can you give few examples of final classes defined in Java API?
Differentiate final from finally and finalize()?
Can we declare a class as static?
When can a method be defined as static?
What are the restrictions imposed on a static method or a static block of code?
If you want to to print "Hello" even before main() is executed, how will you achieve that?
Explain the significance of static variable?
Can a static variable be declared inside a method?
What is an Abstract Class and what is its purpose?
Can an abstract class be declared final?
What is the use of an abstract variable?
Can you create an object of an abstract class?
Can an abstract class be defined without any abstract methods?
Class C implements Interface I containing method m1 and m2 declarations. Class C has provided implementation for method m2. Can i create an object of Class C?
Can a method inside an Interface be declared as final?
Can an Interface implement another Interface?
Can an Interface extend another Interface?
Can a Class extend more than one Class?
Why an Interface is able to extend more than one Interface but a Class cannot extend more than one Class?
Can an Interface be final?
Can a class be defined inside an Interface?
Can an Interface be defined inside a class?
What is a Marker Interface?
Overloading and Overriding achieve which all object oriented concepts?
Why is operator overloading not supported by JAVA?
Can private and protected modifiers be defined for variables in interfaces?
What is Externalizable?
What are the modifiers allowed for methods in an Interface?
What is a local, member and a class variable?
What is an abstract method?
What value does read() return when it reaches the end of a file?
Can you cast a Byte object to a double value?
Differentiate between a static and a non-static inner class?
What is an object's lock and which objects have locks?
What is the % operator?
When can an object reference be cast to an interface reference?
Which class is extended by all other classes?
Which non-Unicode letter characters may be used as the first character of an identifier?
What are the restrictions placed on method overloading?
What is casting?
What is the return type of a program's main() method?
Where can the variable be accessed when it is declared as private?
What do you understand by private, protected and public?
Explain Downcasting.
What modifiers may be used with an inner class that is a member of an outer class?
How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
What are the restrictions placed on the location of a package statement within a source code file?
What is a native method?
What are order of precedence and associativity and how are they used?
Can an anonymous class be declared as implementing an interface and extending a class?
What is the range of the char type?
What is the range of the short type?
Why doesn't operator overloading exist?
What does it mean when we say that a method or field is "static"?
Is null a keyword?
Which characters may be used as the second but not as the first character of an identifier?
Is the ternary operator written x : y ? z or x ? y : z ?
How is rounding performed under integer division?
If a class is declared without any access modifiers, where may the class be accessed?
Does a class inherit the constructors of its superclass?
Name the eight primitive Java types.
What are the restrictions that are placed on the values of each case of a switch statement?
Differentiate between a while statement and a do while statement?
What all modifiers can be used with a local inner class?
When does the compiler supply a default constructor for a class?
Where may a method be accessed if it is declared as protected?
Elaborate the legal operands of the instance of operator?
Are true and false keywords?
What happens when you add a double value to a String?
Differentiate between inner class and nested class.
Can an abstract class be final?
What is numeric promotion?
Differentiate between a public and a non-public class?
To what value is a variable of the boolean type automatically initialized?
Differentiate between the prefix and postfix forms of the ++ operator.
What are the restrictions that are placed on method overriding?
What is a Java package and how is it used?
What modifiers may be used with a top-level class?
Differentiate between an if statement and a switch statement?
What are the practical benefits, if any, of importing a specific class rather than an entire package (e.g.
import java.net.* versus import java.net.Socket)?
Can we overload a method based on different return type but same argument type?
What happens to a static variable that is defined within a method of a class?
How many static initializers are there?
Differentiate between method overriding and overloading?
What is constructor chaining and how is it achieved in Java?
What is the difference between the Boolean & operator and the && operator?
Which Java operator is right associative?
Can a double value be cast to a byte?
What is the difference between a break statement and a continue statement?
Can a for statement loop indefinitely?
To what value is a variable of the String type automatically initialized?
Differentiate between a field variable and a local variable.
How are this() and super() used with constructors?
What does it mean that a class or member is final?
What does it mean that a method or class is abstract?
What is a transient variable?
How does Java handle integer overflows and underflows?
What is the difference between the >> and >>> operators?
Is size of a keyword?
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