Java Programming in Cmd: Everything You Need to Get Started
So you want to learn Java programming but don't have an IDE installed yet? No problem, you can get started with Java using just your command line. CMD, or the Windows Command Prompt, has everything you need to compile and run simple Java programs. While an IDE makes life easier down the road, using the command line is a skill every programmer should learn. In this article, we'll show you how to set up a Java dev environment using nothing but CMD, how to compile your first Java program, and how to run it. By the end, you'll be writing, compiling and executing Java code like a pro using only your trusty command prompt. No heavy installs required to start learning one of the most in-demand programming languages. Ready to get your hands dirty? Let's dive in and master Java the old school way.
What Is Java Programming?
Java is a popular programming language used to develop mobile apps, software, and other systems. To get started with Java programming, you'll need to download the Java Development Kit (JDK) which includes the Java Runtime Environment (JRE) and Java compiler.
Once you have the JDK installed, you can write your first Java program. Open your command line or terminal and create a file called HelloWorld.java. Type or copy and paste this code into the file:
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
```
This simple program prints "Hello, World!" to the console. To compile your code, enter:
```
javac HelloWorld.java
```
Then run it with:
```
java HelloWorld
```
You should see the greeting printed out. Congrats, you've written your first Java program!
Java programs are made up of classes which contain methods. The HelloWorld class has one method called main which is executed when you run the program. The System.out.println() method prints the message to the console.
To build more complex programs, you'll learn about data types, variables, conditional logic, loops, objects, and more. Java is a very robust language used by many large tech companies, so learning it opens you up to many opportunities. With practice, you'll be coding in Java in no time!
Why Use the Windows Command Prompt for Java Programming?
Why bother learning Java programming in the command prompt when you have fancy IDEs nowadays? Here are a few good reasons:
Simplicity
The Windows command prompt is a simple, lightweight interface. No distractions, just you and the code. This simplicity helps you focus on learning the core Java skills without the IDE doing work for you behind the scenes.
Understanding the Compilation Process
When you compile and run a Java program in the command prompt, you can see exactly what's happening. You'll manually compile your code into bytecode using javac, then execute it with java. This helps you understand how Java code is compiled and run, which makes you a stronger programmer.
Appreciating IDEs More
Once you get good at Java programming in the command prompt, you'll have a whole new appreciation for integrated development environments (IDEs). Doing things manually helps you understand and value the automation that IDEs provide. This will make you a power user of tools like Eclipse or IntelliJ IDEA.
Useful Skill
Knowing how to compile and run Java from the command line is a useful skill to have. What if you encounter a system where you only have access to a command prompt? What if you need to compile or run Java code on a server? The command prompt is a universally available tool, so these skills will serve you well as a Java programmer.
Learning Java in the Windows command prompt may feel awkward at first, but it provides valuable benefits that will make you a stronger, more well-rounded programmer. Give it a try—you might just grow to enjoy the simplicity!
Downloading and Installing Java and the JDK
To get started with Java programming on the command line, you'll first need to download and install a few essential tools.
Downloading the Java Development Kit (JDK)
The JDK, or Java SE Development Kit, contains all the resources you need to develop Java applications. You can download the latest version for your operating system at oracle.com/java/technologies/javase-downloa... Look for the Java SE JDK and download the appropriate installer.
Once downloaded, open the installer and follow the onscreen prompts to install the JDK. The installation process typically only takes a few minutes. Make sure to install the JDK and not just the Java Runtime Environment (JRE). The JRE only runs Java programs, it does not allow you to develop them.
Setting the JAVA_HOME Environment Variable
After installing the JDK, you need to set the JAVA_HOME environment variable to the location of the JDK installation on your computer. This allows your operating system to find the Java compiler and tools.
To set the JAVA_HOME variable on Windows:
Open the Control Panel and go to System → Advanced system settings.
Click "Environment Variables".
Under "System variables", click "New...".
Enter "JAVA_HOME" as the Variable name.
Enter the path to your JDK installation for the Variable value. For example, C:\Program Files\Java\jdk-15.0.1
Click "OK" to save.
You may need to restart your computer for the change to take effect.
To check if the JAVA_HOME variable is set properly, open your command line or terminal window and run echo %JAVA_HOME%. It should print the path you entered. Congratulations, you now have Java set up and ready to run on the command line!
Writing Your First Java Program in CMD
To write your first Java program in the Windows Command Prompt, follow these steps:
Open the Command Prompt
Open the Start menu and search for "Command Prompt". Select the "Command Prompt" app to open it.
Set the JAVA_HOME environment variable
The JAVA_HOME environment variable tells your system where the JDK is installed. To set it, enter the following command:
```
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_271
```
Replace the path with the location of your JDK installation.
Compile your Java program
Create a file called HelloWorld.java and enter the following code:
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
```
To compile the program, enter:
```
javac HelloWorld.java
```
This will create a HelloWorld.class file, which is the compiled Java bytecode.
Run your program
To run the compiled Java program, enter:
```
java HelloWorld
```
You should see the output:
```
Hello, World!
```
Congratulations, you've written and run your first Java program using the Command Prompt! Let me know if you have any other questions about Java programming.
Compiling and Running Java Programs From the Command Line
Compiling and running Java programs from the command line may seem intimidating at first, but it’s actually quite straightforward. To get started, you'll need a few tools:
The Java Development Kit (JDK)
The JDK includes the Java Runtime Environment (JRE), the Java compiler (javac), and other tools you'll need to build and run Java programs. Download the latest version of the JDK for your operating system.
A Text Editor
You'll need a simple text editor to write your Java code. Some good options are Notepad (for Windows), TextEdit (for Mac), or Sublime Text. Avoid using a word processor like Microsoft Word.
The Command Line
The command line interface (CLI) is how you'll compile and run your programs. On Windows, use Command Prompt or PowerShell. On Mac/Linux, use the Terminal app.
Writing Your Code
Create a file called HelloWorld.java and add this code:
```java
public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}
```
Compiling Your Code
Open your CLI and navigate to the folder containing your code. Enter the command:
javac HelloWorld.java
This will compile your code into a file called HelloWorld.class.
Running Your Program
Enter this command to run your program:
java HelloWorld
You should see Hello, World! printed out, indicating your program ran successfully!
Congrats, you've compiled and run your first Java program from the command line! Let me know if you have any other questions about getting started with Java.