Progressive Infotech Interview Questions and Answers

Checked exceptions are checked at compile-time while unchecked exceptions are not.

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

• Unchecked exceptions are those that are not checked at compile-time and do not need to be handled or declared in the method signature.

• Examples of checked exceptions include IOException, ClassNotFoundException, and SQLException.

• Examples of unchecked exceptions include NullPointerE...read more

An object is an instance of a class. A class is a blueprint or template for creating objects.

• A class defines the properties and behaviors of objects

• An object is created from a class using the 'new' keyword

• Multiple objects can be created from a single class

• Classes can inherit properties and behaviors from other classes

• Example: Class - Car, Object - Honda Civic

String buffer is synchronized and thread-safe while string builder is not.

• String buffer is slower than string builder due to synchronization.

• String builder is faster but not thread-safe.

• String buffer is preferred for multi-threaded applications.

• String builder is preferred for single-threaded applications.

• Both classes are used for manipulating strings efficiently.

try-catch-finally is used for handling exceptions in code.

• try block contains the code that may throw an exception

• catch block catches the exception thrown by try block

• finally block contains code that will be executed regardless of exception

• Multiple catch blocks can be used for handling different types of exceptions

ArrayList is a dynamic data structure while Array is a static data structure.

• ArrayList can grow or shrink dynamically while Array has a fixed size.

• ArrayList can store objects of any type while Array can only store elements of the same data type.

• ArrayList provides built-in methods for insertion, deletion, and searching while Array does not.

• Example: ArrayList names = new ArrayList(); String[] namesArray = new String[5];

• Example: names.add("John"); names.add("Jane"); namesArray[0...read more

Encapsulation and Inheritance are two important OOPs concepts.

• Encapsulation is the process of binding data and functions that manipulate that data together in a single unit, called a class.

• Inheritance is the process of creating a new class by inheriting properties and methods from an existing class.

• Encapsulation helps in data hiding and abstraction, which makes the code more secure and easy to maintain.

• Inheritance helps in code reusability and saves time and effort in writing...read more