Master Core Java Programming From Scratch

1. Java Development Kit (JDK)

The Java Development Kit (JDK) is the primary software package required for Java development.

It contains the Java compiler, Java runtime tools, debugging tools, documentation tools, and other utilities required to build Java applications.

JDK Components

2. Java Virtual Machine (JVM)

The Java Virtual Machine (JVM) is responsible for executing Java bytecode.

The JVM provides the runtime environment that allows Java applications to run on different operating systems.

Java Source Code
        ↓
     javac
        ↓
Bytecode (.class)
        ↓
       JVM
        ↓
 Operating System

3. Java Runtime Environment (JRE)

The Java Runtime Environment (JRE) provides the components required to run Java applications.

It includes the JVM and supporting runtime libraries.

JDK vs JRE vs JVM

4. Java IDEs

An IDE (Integrated Development Environment) provides tools for writing, running, debugging, and managing Java applications.

5. Java from Command Line

Java programs can also be developed without an IDE by using the JDK tools directly from the command line.

javac HelloWorld.java

java HelloWorld

The javac command compiles the source file and generates a bytecode class file. The java command launches the application through the JVM.

6. Check Java Installation

After installing a JDK, you can verify the installed Java version from the terminal.

java -version

To check the Java compiler version, use:

javac -version

7. Compile and Run a Java Program

Consider the following Java program:

public class HelloWorld {

    public static void main(String[] args) {

        System.out.println("Wel-Come CIIT Training Institute👨‍🏫...!");

    }

}

Step 1: Save the file

Save the source code as:

HelloWorld.java

Step 2: Compile the program

javac HelloWorld.java

Step 3: Run the program

java HelloWorld

Output

Wel-Come CIIT Training Institute👨‍🏫...!

8. JAVA_HOME

JAVA_HOME is an environment variable commonly used by Java development tools and build systems to identify the installed JDK location.

Build tools such as Maven and Gradle can use the configured Java environment when compiling and running projects.

9. Java Build Tools

Development Best Practices

• Use a supported JDK version.
• Keep the JDK and build tools properly configured.
• Use an IDE for larger Java projects.
• Learn command-line Java compilation as a foundation.
• Use Maven or Gradle for dependency and build management.
• Keep Java versions consistent across development and deployment environments.