Runnable example
public class Main {
public static void main(String[] args) {
System.out.println("Hello World");
}
}This editor will be used in the entire tutorial to demonstrate the different aspects of Java.
Java Install
However, if you want to run Java on your own computer, follow the instructions below.
Some PCs might have Java already installed.
To check if you have Java installed on a Windows PC, search in the start bar for Java or type the following in Command Prompt (cmd.exe):
C:\Users\
Your Name
>java -versionIf Java is installed, you will see something like this (depending on version):
If you do not have Java installed on your computer, you can download it at oracle.com .
Note
In this tutorial, we will write Java code in a text editor. However, it is possible to write Java in an Integrated Development Environment, such as IntelliJ IDEA, Netbeans or Eclipse, which are particularly useful when managing larger collections of Java files.
Java Quickstart
In Java, every application begins with a class name, and that class must match the filename.
Let's create our first Java file, called Main.java , which can be done in any text editor (like Notepad).
The file should contain a "Hello World" message, which is written with the following code:
Runnable example
public class Main {
public static void main(String[] args) {
System.out.println("Hello World");
}
}Don't worry if you don't understand the code above - we will discuss it in detail in later chapters. For now, focus on how to run the code above.
Save the code in Notepad as "Main.java". Open Command Prompt (cmd.exe), navigate to the directory where you saved your file, and type "javac Main.java":
C:\Users\
Your Name
>javac Main.javaThis will compile your code. If there are no errors in the code, the command prompt will take you to the next line. Now, type "java Main" to run the file:
C:\Users\
Your Name
>java MainThe output should read
Hello WorldCongratulations! You have written and executed your first Java program.