TCS Java Developer Interview Questions and Answers for Freshers

Polymorphism allows methods to do different things based on the object that it is acting upon, enhancing flexibility in code.

• Polymorphism is a core concept in Object-Oriented Programming (OOP).

• It allows methods to be defined in multiple forms.

• Example: A method 'draw()' can behave differently for 'Circle' and 'Square' classes.

• There are two types: compile-time (method overloading) and runtime (method overriding).

• Ove...read more

A classLoader in Java is a part of the Java Runtime Environment that loads classes into memory.

• ClassLoaders are responsible for finding and loading class files into the Java Virtual Machine (JVM).

• There are three main types of ClassLoaders: Bootstrap, Extension, and Application ClassLoader.

• The Bootstrap ClassLoader loads core Java classes from the JDK's rt.jar file.

• The Extension ClassLoader loads classes from the J...read more

Compile time polymorphism is achieved through method overloading, while runtime polymorphism is achieved through method overriding.

• Compile time polymorphism is also known as static polymorphism.

• It is achieved by having multiple methods in the same class with the same name but different parameters.

• Example: method overloading in Java.

• Runtime polymorphism is also known as dynamic polymorphism.

• It is achieved by having...read more

Truncate is a SQL command used to delete all rows from a table without logging the individual row deletions.

• Truncate is a DDL (Data Definition Language) command in SQL.

• It is used to quickly delete all rows from a table, but it does not log individual row deletions.

• Truncate is faster than using the DELETE command, as it does not generate individual row deletion logs.

• Truncate also resets any auto-incrementing keys i...read more

Exceptions in Spring Boot can be handled using try-catch blocks, @ExceptionHandler annotation, and global exception handling.

• Use try-catch blocks to handle exceptions within a specific method.

• Use @ExceptionHandler annotation to handle exceptions at the controller level.

• Implement a global exception handler using @ControllerAdvice and @ExceptionHandler annotations.

• Customize error responses using ResponseEntityExcept...read more

Constructor is a special method that is used to initialize objects in Java.

• Constructor has the same name as the class name

• It does not have a return type

• It can be overloaded

• It is called automatically when an object is created

• Example: public class Car { public Car() { // constructor code here } }