30+ NISA Global Interview Questions and Answers

In Java, == compares memory addresses while .equals() compares the actual values of objects.

• == compares memory addresses of objects

• .equals() compares the actual values of objects

• Use == for comparing primitive data types

• Use .equals() for comparing objects like Strings

In Java, == compares memory addresses while .equals() compares the actual content of objects.

• == compares memory addresses of objects, while .equals() compares the actual content of objects.

• == is used to compare primitive data types, while .equals() is used to compare objects.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true.

The '==' operator compares memory addresses of objects, while the .equals() method compares the content or value of objects.

• Use '==' for comparing memory addresses of objects.

• Use .equals() for comparing the content or value of objects.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will return false, but str1.equals(str2) will return true.

The question is asking to create a class with certain restrictions like being final, having private and final fields, and no setter methods.

• Declare the class as final to prevent it from being subclassed.

• Make all fields private and final to ensure encapsulation and immutability.

• Provide no setter methods to enforce read-only access to the fields.

The question explains the difference between == and .equals() in Java for comparing object references and content.

• Use == to compare object references (memory location)

• Use .equals() to compare the actual content or values of the objects

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true

The final keyword in Java is used to restrict the user from changing the value of a variable, making a method not overrideable, or preventing a class from being subclassed.

• Final variables cannot be reassigned once initialized

• Final methods cannot be overridden in subclasses

• Final classes cannot be subclassed

• Final parameters in a method cannot be modified within the method

The static keyword in Java is used to create class-level variables and methods that can be accessed without creating an instance of the class.

• Static variables are shared among all instances of a class.

• Static methods can be called without creating an instance of the class.

• Static blocks are used to initialize static variables.

• Static keyword can also be used to create static nested classes.

Immutable class in Java cannot be modified after creation, ensuring data integrity.

• Make the class final so it cannot be extended

• Make all fields private and final so they cannot be modified

• Do not provide setter methods, only getter methods to access the fields

• If the class contains mutable objects, make sure to return a deep copy of them in getter methods

The final keyword in Java is used to restrict the user from changing the value of a variable, making a method not overrideable, or making a class not inheritable.

• Final variables cannot be reassigned once initialized.

• Final methods cannot be overridden in subclasses.

• Final classes cannot be extended by other classes.

No, a Java class cannot extend multiple classes.

• Java does not support multiple inheritance for classes.

• A class can only extend one other class, but can implement multiple interfaces.

• Example: class MyClass extends ParentClass implements Interface1, Interface2

The default value of an int in Java is 0.

• In Java, when an int variable is declared but not initialized, it is automatically assigned the default value of 0.

• For example, int num; // num is assigned the default value of 0.

High level languages are closer to human language, mid level languages are a mix of high and low level, and low level languages are closer to machine language.

• High level languages are easier to read and write, like Java or Python.

• Mid level languages provide a balance between high and low level, like C++.

• Low level languages are closer to machine language, like Assembly.

The final keyword is used to declare final variables, final methods, and final classes in Java.

• Final variables cannot be reassigned once initialized.

• Final methods cannot be overridden in subclasses.

• Final classes cannot be extended.

There are three main types of programming languages: high-level, low-level, and middle-level.

• High-level languages are closer to human language and easier to understand, like Java, Python, and Ruby.

• Low-level languages are closer to machine language and harder to understand, like Assembly and Machine Code.

• Middle-level languages, like C and C++, combine elements of both high-level and low-level languages.

The difference between == and equals() in Java for comparing object references and values.

• Use == to compare object references (memory location)

• Use equals() to compare object values

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true

The size of an int in Java is 4 bytes.

• An int in Java is a 32-bit signed integer.

• It can hold values ranging from -2,147,483,648 to 2,147,483,647.

• The size of an int is fixed at 4 bytes on all platforms.

In Java, == compares object references, while .equals() compares object values.

• Use == to compare if two object references point to the same memory location.

• Use .equals() to compare if two objects have the same values.

• Example: String str1 = new String("hello"); String str2 = new String("hello"); str1 == str2 will be false, but str1.equals(str2) will be true.

Yes, the size of an int in Java is indeed 4 bytes (32 bits).

• An int in Java can hold values ranging from -2,147,483,648 to 2,147,483,647.

• The size of an int can be confirmed using the 'Integer.SIZE' constant in Java.

• Using 'Integer.BYTES' will give the size of an int in bytes.

Java related frameworks are tools that provide pre-written code to help developers build applications more efficiently.

• Frameworks like Spring, Hibernate, and Struts are commonly used in Java development.

• They provide libraries, APIs, and tools to simplify the development process.

• Frameworks help with tasks like database access, security, and dependency injection.

• Popular Java frameworks include Spring Boot, JavaServer Faces (JSF), and Apache Wicket.

JAVA is a high-level programming language known for its portability, security, and object-oriented features.

• JAVA is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM)

• It is object-oriented, allowing for modular and reusable code

• JAVA is known for its security features, such as sandboxing and encryption

• It is widely used for developing web applications, mobile apps, and enterprise software

Java stands for Just Another Virtual Machine

• Java stands for Just Another Virtual Machine

• It is a high-level programming language developed by Sun Microsystems

• Java code is compiled into bytecode that runs on any Java Virtual Machine (JVM)

Java is a high-level, object-oriented programming language known for its portability and versatility.

• Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM)

• It is object-oriented, allowing for modular and reusable code

• Java is known for its robust standard library, which includes tools for networking, data structures, and more

JAVA stands for Java Virtual Machine

• JAVA stands for Java Virtual Machine

• It is a virtual machine that enables a computer to run Java programs

• It provides a platform-independent execution environment for Java applications

Java is a high-level programming language known for its portability, security, and object-oriented features.

• Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM).

• It is known for its robust security features, such as sandboxing and encryption.

• Java is object-oriented, allowing for the creation of reusable code through classes and objects.

Yes, the default value of an int in Java is 0.

• In Java, when an int variable is declared but not initialized, it will have a default value of 0.

• For example, int num; will have a default value of 0.

• This default value is assigned by the Java Virtual Machine (JVM) when memory is allocated for the variable.

Java is a high-level, object-oriented programming language known for its portability, security, and versatility.

• Java is platform-independent, meaning it can run on any device with a Java Virtual Machine (JVM)

• It is object-oriented, allowing for modular and reusable code

• Java is known for its strong security features, such as sandboxing and encryption

• Popular Java frameworks include Spring, Hibernate, and Apache Struts

Java program to check if a number is prime

• Create a function that takes an integer as input

• Check if the number is less than 2, return false

• Iterate from 2 to the square root of the number, check for divisibility

• If the number is divisible by any number, return false

• Otherwise, return true

A prime number is a number greater than 1 that can only be divided by 1 and itself.

• Prime numbers are integers greater than 1

• They have only two factors: 1 and the number itself

• Examples of prime numbers: 2, 3, 5, 7, 11, 13

Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

• Abstract class can have constructors, member variables, and methods, while interface cannot.

• A class can implement multiple interfaces but can only extend one abstract class.

• Abstract classes are used to define a common behavior among subclasses, while interfaces are used to define a contract for classes to implement.

• Example: Abstract class - Animal with abstract metho...read more

JVM stands for Java Virtual Machine, which is an abstract machine that enables a computer to run Java programs.

• JVM is responsible for converting Java bytecode into machine code that can be executed by the computer's operating system.

• It provides a platform-independent execution environment for Java programs.

• JVM manages memory, handles garbage collection, and provides security features for Java applications.

• Examples of JVM implementations include Oracle HotSpot, OpenJ9, and Gra...read more