update

content/courses/prog-intro/lectures/intro/intro.md

@@ -143,3 +143,49 @@ The advanced way of implementing the garbage collection is *traversing the graph
 
 You can go and learn about it [here](https://google.github.io/styleguide/javaguide.html). 
 
+# Hello World!
+
+Let's create a file and name it `Helloworld.java`. I will annotate each code listing with a top comment with a filename for general understanding where the file is located and how it's called. And let's create a class.
+
+```java
+// Helloworld.java
+
+public class Helloworld {
+
+}
+```
+
+> [!NOTE]
+> Notice, that the name of the class should be the same as the name of the file it which it is created.
+
+Let's define a method called `main` inside this class
+
+```java
+// Helloworld.java
+
+public class Helloworld {
+    public static void main(String[] args) {
+
+    }
+}
+```
+
+This method will take an ***array of Strings*** called `args` as it's argument.
+
+> [!NOTE]
+> The name `args` is just a common name. You can call it whatever you want. For example `params`.
+
+This method is being called at the start of our program.
+
+Let's try to *print* `Hello, world` to the console.
+
+```
+// Helloworld.java
+
+public class Helloworld {
+    public static void main(String[] args) {
+        System.out.println("Hello, world");
+    }
+}
+```
+