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50 Programming Interview Questions-Java Methods

Updated: Dec 17, 2023


Programming Interview Questions Java - Methods

In this comprehensive blog post, we have compiled a curated list of challenging Java coding questions and answers, programming interview questions in Java, designed to test your coding skills, problem-solving abilities, and knowledge of Java fundamentals.


Q1: What is a method in Java?

A1: A method in Java is a block of code that performs a specific task. It can be called or invoked to execute its defined functionality.


Q2: How are methods defined in Java?

A2: Methods are defined with the following syntax: returnType methodName(parameter1Type parameter1Name, parameter2Type parameter2Name, ...) {

// Method body

}


Q3: What is the purpose of the return statement in a method?

A3: The return statement is used to specify the value that a method should return to the caller. It also exits the method's execution.


Q4: Can a Java method have multiple return statements?

A4: Yes, a method can have multiple return statements. The appropriate return statement is executed based on the condition.


Q5: What is a method's return type?

A5: The return type of a method defines the data type of the value that the method will return when it is called. It is specified before the method name in the method declaration.


Q6: How do you call or invoke a method in Java?

A6: To call a method, you use the method's name followed by parentheses, passing any required arguments inside the parentheses.


Q7: What is method overloading in Java?

A7: Method overloading is the ability to define multiple methods in the same class with the same name but different parameter lists (different number or types of parameters).


Q8: What is a constructor method in Java?

A8: A constructor is a special type of method used to initialize objects when they are created. It has the same name as the class and does not specify a return type.


Q9: What is method overriding in Java?

A9: Method overriding is the process of providing a new implementation for a method that is already defined in the superclass (parent class). It allows a subclass (child class) to provide its own version of a method.


Q10: What is the void return type in a method declaration?

A10: The void return type indicates that a method does not return any value. It is used for methods that perform an action but do not produce a result.


Q11: What are access modifiers in Java, and how do they affect methods?

A11: Access modifiers (e.g., public, private, protected, package-private) determine the visibility and accessibility of methods. They control which classes can access and call a method.


Q12: What is a static method in Java?

A12: A static method belongs to the class rather than an instance of the class. It can be called using the class name and does not require an instance of the class to be created.


Q13: What is a non-static method (instance method) in Java?

A13: A non-static method, also known as an instance method, belongs to an instance of a class. It is called on an object created from the class.


Q14: Can you have a method with the same name in both the superclass and subclass?

A14: Yes, you can have a method with the same name in both the superclass and subclass. This is called method overriding, where the subclass provides its own implementation of the method.


Q15: What is the purpose of the this keyword in a method?

A15: The this keyword refers to the current instance of the class and is often used to distinguish between instance variables and method parameters with the same name.


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Java Back-End Development


Q16: What is the purpose of the super keyword in a method?

A16: The super keyword is used to call a method or access a field from the superclass (parent class) when there is a method or field with the same name in the subclass.


Q17: What is a method signature in Java?

A17: A method signature consists of the method's name and its parameter list (number and types of parameters). It does not include the return type.


Q18: What is the difference between a method declaration and a method invocation?

A18: A method declaration defines the method's name, return type, and parameters. A method invocation is when the method is called or executed with specific arguments.


Q19: What is a parameterized method in Java?

A19: A parameterized method is a method that accepts one or more parameters (input values) to perform its task. The parameters are specified in the method's parameter list.


Q20: What is a method's scope in Java?

A20: A method's scope defines where in the code the method can be called or accessed. It is determined by the access modifier and the class in which the method is defined.


Q21: What is method chaining in Java?

A21: Method chaining is a technique where multiple method calls are chained together in a single line, typically on the same object, to perform a series of operations.


Q22: How do you pass arguments to a method in Java?

A22: Arguments are passed to a method by specifying their values or references within the parentheses when calling the method.


Q23: What is method visibility?

A23: Method visibility refers to whether a method can be accessed or called from other classes. It is controlled by access modifiers (e.g., public, private, protected, package-private).


Q24: What is the final keyword used for in method declarations?

A24: The final keyword, when applied to a method, indicates that the method cannot be overridden by subclasses. It provides method-level immutability.


Q25: What is a recursive method in Java?

A25: A recursive method is a method that calls itself to solve a problem. It often involves breaking down a problem into smaller, similar sub-problems.


Q26: What is method abstraction in Java?

A26: Method abstraction is the concept of defining method signatures in an interface or abstract class without providing the implementation. Subclasses must implement these methods.


Q27: What is the static keyword used for in Java method declarations?

A27: The static keyword in a method declaration indicates that the method belongs to the class rather than an instance of the class. It can be called using the class name.


Q28: How do you define a method that accepts a variable number of arguments in Java?

A28: You can use varargs (variable-length argument lists) by specifying an ellipsis (...) after the parameter type in the method declaration. For example: void printNumbers(int... numbers).


Q29: What is method signature overloading in Java?

A29: Method signature overloading is a form of method overloading where multiple methods in a class have the same name but different parameter lists, including a different number or types of parameters.


Q30: What is the purpose of the throws clause in a method declaration?

A30: The throws clause is used to declare checked exceptions that a method may throw during its execution. It informs the caller about the possible exceptions that need to be handled.


Core Java Programming

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Q31: What is a static initializer block in Java, and how is it different from a constructor?

A31: A static initializer block is a block of code within a class that is executed when the class is loaded into memory, regardless of whether any instances of the class are created. It is different from a constructor, which is called when an object is instantiated.


Q32: What is method visibility and access control in Java?

A32: Method visibility and access control refer to the rules that determine which classes and methods can access and call a particular method. Access modifiers (public, private, protected, package-private) control method visibility.


Q33: How is method overloading different from method overriding?

A33: Method overloading involves defining multiple methods in the same class with the same name but different parameter lists. Method overriding occurs when a subclass provides its own implementation for a method that is already defined in the superclass.


Q34: Can you have a method with the same name and parameter list in two different classes?

A34: Yes, you can have methods with the same name and parameter list in two different classes. This is not considered method overloading or overriding because the methods are in separate classes.


Q35: What is a default method in an interface in Java?

A35: A default method in an interface is a method that provides a default implementation. It allows adding new methods to interfaces without breaking existing classes that implement the interface.


Q36: What is method abstraction in the context of interfaces?

A36: Method abstraction in interfaces refers to declaring method signatures without providing implementations. Concrete classes that implement the interface must provide their own implementations of these methods.


Q37: What is the purpose of the @Override annotation in Java method declarations?

A37: The @Override annotation is used to indicate that a method in a subclass is intended to override a method in the superclass. It helps catch errors at compile-time if the method signature doesn't match.


Q38: What is method composition in Java?

A38: Method composition is the practice of combining multiple methods to perform a more complex operation. It promotes code reuse and modular design.


Q39: What are static import statements, and how are they used with methods?

A39: Static import statements allow you to use static methods and fields from a class without specifying the class name. They make it easier to use methods without prefixing them with the class name.


Q40: What is the purpose of method synchronization in Java?

A40: Method synchronization is used to control access to a method by multiple threads. It ensures that only one thread can execute the synchronized method at a time, preventing concurrent access issues.


Q41: What is method chaining, and how is it achieved in Java?

A41: Method chaining is a technique where multiple method calls are chained together in a single line, typically on the same object. It is achieved by having each method return the object itself (this) to allow further method calls.


Q42: What is the difference between instance methods and class methods in Java?

A42: Instance methods operate on an instance of a class (an object) and can access instance variables. Class methods (static methods) belong to the class itself and do not operate on specific instances. They can only access static members of the class.


Q43: What is the purpose of the final modifier in a method declaration?

A43: The final modifier, when applied to a method, indicates that the method cannot be overridden by subclasses. It provides method-level immutability.


Q44: What is method hiding in Java?

A44: Method hiding occurs when a subclass defines a static method with the same name as a static method in the superclass. The subclass's method "hides" the superclass's method.


Q45: How can you prevent a method from being overridden in Java?

A45: You can prevent a method from being overridden by using the final modifier in the method declaration or by declaring the entire class as final to prevent any method overrides.


Q46: What is a lambda expression, and how can it be used with methods in Java?

A46: A lambda expression is a concise way to represent an anonymous function. It can be used to define methods in functional interfaces or to pass behavior as an argument to other methods.


Q47: What is method reference in Java, and how does it work?

A47: Method reference is a shorthand notation for invoking a method. It is used to simplify the lambda expressions when the lambda body calls an existing method.


Q48: What is a method handle in Java?

A48: A method handle is a typed, directly executable reference to a method, constructor, field, or similar low-level operation. It provides more flexibility and control than method references.


Q49: What is a default method in an interface, and why was it introduced in Java 8?

A49: A default method in an interface is a method with a default implementation. It was introduced in Java 8 to allow interfaces to evolve without breaking existing implementations.


Q50: How is method recursion different from regular method calls?

A50: Method recursion involves a method calling itself, either directly or indirectly. It is used for solving problems that can be divided into smaller, similar sub-problems. Regular method calls involve calling methods other than the caller itself.

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