What is the purpose of garbage collection in Java?

Vaibhav Kothia May 26, 2023 0 Comments

Garbage collection is an important part of Java that helps to manage memory. It is the process of reclaiming memory from objects that are no longer in use. Garbage collection is an automatic process in Java that runs in the background and frees up memory by deleting objects that are no longer being used.

An example of garbage collection in Java would be when a program creates an instance of an object. After the object is no longer needed, the memory allocated to it is freed up by the garbage collector. This allows the memory to be used for other objects.

What is a Java applet?

Vaibhav Kothia May 26, 2023 0 Comments

A Java applet is a small application written in the Java programming language that can be embedded in a web page. It runs inside the web browser and works at client side.

An example of a Java applet is an animation or a game that can be played within a web page. Another example is a calculator, which can be used to perform calculations within a web page.

What is the difference between JDK, JRE, and JVM?

Vaibhav Kothia May 26, 2023 0 Comments

JDK (Java Development Kit): A JDK is an implementation of the Java SE platform that is used to develop Java applications. The JDK includes the JRE as well as tools for developing, debugging, and monitoring Java applications. For example, the JDK includes the javac compiler, which is used to compile Java source code into Java bytecode.

JRE (Java Runtime Environment): A JRE is an implementation of the Java SE platform that is used to run Java applications. The JRE includes the Java Virtual Machine (JVM), class libraries, and other components necessary for running a Java application. For example, the JRE includes the java command, which is used to launch Java applications.

JVM (Java Virtual Machine): A JVM is a virtual machine that runs Java bytecode. The JVM is responsible for interpreting and executing Java bytecode. It also provides runtime services such as memory management, threading, and garbage collection.

What is the purpose of the final keyword in Java?

Vaibhav Kothia May 26, 2023 0 Comments

The final keyword in Java is used to indicate that a variable, method, or class cannot be changed. This helps to prevent any accidental changes to the code that could affect its functionality.

For example, if you wanted to create a class that could not be modified, you could use the final keyword in the class declaration:

public final class MyClass {
// class code here
}

What is the difference between an interface and an abstract class in Java?

Vaibhav Kothia May 26, 2023 0 Comments

An interface is a collection of abstract methods, meaning that they are not implemented in the interface itself. Interfaces can also contain constants, default methods, static methods, and nested types. An example of an interface in Java is:

public interface Animal {
public void eat();
public void sleep();
}

An abstract class is a class that contains both abstract and non-abstract methods. Abstract classes can also contain constants, default methods, static methods, and nested types. An example of an abstract class in Java is:

public abstract class Animal {
public abstract void eat();
public void sleep(){
System.out.println(“Sleeping…”);
}
}

What is the concept of Object-Oriented Programming (OOP) in Java?

Vaibhav Kothia May 26, 2023 0 Comments

Object-Oriented Programming (OOP) is a programming paradigm based on the concept of objects, which contain data and methods that operate on that data. OOP is used to structure a program into classes and objects, which can be used to create a more intuitive and organized code structure. In Java, OOP is used to create classes that contain both data and methods. These classes are then used to create objects that can be used to interact with the data and methods of the class.

For example, a class called Car could contain data such as make, model, year, and color. It could also contain methods such as start, stop, and accelerate. This class could then be used to create a Car object called myCar, which could be used to access and manipulate the data and methods of the Car class.

What is the difference between JDK, JRE, and JVM?

Vaibhav Kothia May 26, 2023 0 Comments

JDK: The Java Development Kit (JDK) is a software development environment used for developing Java applications and applets. It includes the Java Runtime Environment (JRE), an interpreter/loader (Java), a compiler (javac), an archiver (jar), a documentation generator (Javadoc) and other tools needed in Java development. Example: Eclipse, NetBeans, IntelliJ IDEA

JRE: The Java Runtime Environment (JRE) is a set of software tools for developing Java applications. It consists of a Java Virtual Machine (JVM) and a set of libraries and other files that provide the class libraries and other resources needed to run Java programs. Example: Java Runtime Environment 8

JVM: The Java Virtual Machine (JVM) is the virtual machine that runs Java bytecode. It is the code execution component of the Java platform. It converts Java bytecode into machine language and executes it. Example: Hotspot JVM, JRockit JVM

What is the purpose of the Java Virtual Machine (JVM)?

Vaibhav Kothia May 26, 2023 0 Comments

The Java Virtual Machine (JVM) is a virtual machine that enables a computer to run a Java program. It provides the runtime environment in which Java bytecode can be executed. It is the component of the Java Runtime Environment (JRE) that interprets compiled Java code and executes it on the computer.

An example of how the JVM works is when a Java program is compiled, the compiled code is called bytecode. This bytecode is platform-independent and can run on any system that has a JVM installed. The JVM reads the bytecode, translates it into machine code, and then executes it.

What is the difference between Java and JavaScript?

Vaibhav Kothia May 26, 2023 0 Comments

Java is a general-purpose programming language that is class-based, object-oriented, and designed to have as few implementation dependencies as possible. It is intended to let application developers “write once, run anywhere” (WORA), meaning that compiled Java code can run on all platforms that support Java without the need for recompilation.

JavaScript is a scripting language that is used to create and control dynamic website content, i.e. things that move, refresh, or otherwise change on your screen without requiring you to manually reload a web page. JavaScript is also used in game development and mobile app development.

Example:

Java:

public class HelloWorld {
public static void main(String[] args) {
System.out.println(“Hello World!”);
}
}

JavaScript:

console.log(“Hello World!”);

What is the difference between a constructor and a method?

Vaibhav Kothia May 26, 2023 0 Comments

A constructor is a special method that is used to create and initialize an object. It is called when an object is created and is usually used to set up the initial state of the object. For example, the constructor of a class might set the default values for the properties of the object.

A method is a subroutine or function associated with a class. It is used to perform an action or to retrieve data. For example, a method of a class might be used to calculate the area of a rectangle or to retrieve a specific record from a database.