Capgemini Java Developer Interview Questions, Process, and Tips

JDK is a development kit, JRE is a runtime environment, and JVM is a virtual machine for executing Java code.

• JDK includes JRE and development tools like compiler and debugger

• JRE includes JVM and necessary libraries to run Java applications

• JVM is responsible for interpreting Java bytecode and executing it

• JDK is used for developing Java applications, JRE is used for running them

• Example: JDK 8 includes JRE 8 and tools lik...read more

Entry point for Java programs.

• public: Access modifier that allows the method to be called from anywhere.

• static: Method belongs to the class and not to any instance of the class.

• void: Method does not return any value.

• main: Method name that is recognized by JVM as the entry point for the program.

• String args[]: Command line arguments passed to the program as an array of strings.

Yes, Java is platform-independent because of its 'write once, run anywhere' principle.

• Java programs are compiled into bytecode, which can be executed on any platform with a Java Virtual Machine (JVM).

• The JVM acts as an interpreter, translating the bytecode into machine code specific to the underlying platform.

• This allows Java programs to run on different operating systems and hardware architectures without modification...read more

Constructors are special methods used to initialize objects in Java.

• Constructors have the same name as the class they belong to.

• They are called automatically when an object is created.

• They can be overloaded to accept different parameters.

• Example: public class Car { public Car(String make, String model) { ... } }

• Example: Car myCar = new Car("Toyota", "Camry");

The final keyword in Java is used to declare a constant variable or to prevent method overriding and class inheritance.

• Final variables cannot be reassigned once initialized

• Final methods cannot be overridden by subclasses

• Final classes cannot be inherited by other classes

• Example: final int MAX_VALUE = 100;

• Example: final void printMessage() { System.out.println("Hello World!"); }

• Example: final class MyClass { ... }

Java String Pool is a cache of String objects stored in heap memory.

• String literals are automatically added to the pool.

• String objects created using the 'new' keyword are not added to the pool.

• String.intern() method can be used to add a String object to the pool.

• String pool helps in saving memory by reusing common String literals.

Java Strings are immutable to ensure data integrity and security.

• Immutable strings prevent accidental modification of data.

• String pooling optimizes memory usage by reusing existing strings.

• Immutable strings are thread-safe, simplifying concurrent programming.

• String immutability allows for efficient caching and hashing.

• Immutable strings enable safe sharing of string references.