Java Software Engineer Interview Questions and Answers for Freshers

Yes, we can pass values during object creation using constructors.

• Constructors are special methods that are called when an object is created.

• They can take parameters to initialize the object's state.

• Values passed during object creation are used to initialize instance variables.

• Example: public class Person { String name; int age; public Person(String name, int age) { this.name = name; this.age = age; } }

• Example usage: Person person = new Person("John", 30);

Exceptions are errors that occur during program execution. There are two types: checked and unchecked.

• Exceptions are objects that represent errors or exceptional conditions that occur during program execution.

• Checked exceptions are checked at compile time and must be handled or declared in the method signature.

• Unchecked exceptions are not checked at compile time and can be handled or left to propagate up the call stack.

• Examples of exceptions include NullPointerException, Arra...read more

OOP concepts in Java with real time examples

• Encapsulation - hiding implementation details of a class. Example: private variables in a class

• Inheritance - creating a new class from an existing class. Example: subclass extending a superclass

• Polymorphism - ability of an object to take many forms. Example: method overloading and overriding

• Abstraction - showing only necessary details to the user. Example: abstract classes and interfaces

Array is a fixed-size data structure while Array list is a dynamic data structure.

• Array has a fixed size while Array list can grow dynamically.

• Array can store only homogeneous data types while Array list can store heterogeneous data types.

• Array is faster than Array list in terms of accessing elements.

• Array list provides more functionality like add, remove, and search.

• Example of Array: int[] arr = new int[5]; Example of Array list: ArrayList<String> list = new ArrayList<>();

Static keyword is used to create class-level variables and methods.

• 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 import is used to import static members of a class

Collection framework is a set of classes and interfaces that provide a way to store and manipulate groups of objects.

• Collection framework is part of Java's core libraries.

• It includes interfaces like List, Set, and Map, and their respective implementations like ArrayList, HashSet, and HashMap.

• Collections can be sorted, searched, and filtered using various methods.

• Iterators are used to traverse through collections.

• Collections can also be synchronized for thread safety.

• Example: ...read more

Method overloading is having multiple methods with the same name but different parameters. Method overriding is having a method in child class with the same name and signature as in parent class.

• Method overloading is compile-time polymorphism

• Method overriding is run-time polymorphism

• Method overloading is used to provide different ways of calling the same method

• Method overriding is used to provide a specific implementation of a method in a child class

• Method overloading can hav...read more