Hello World
30 minutes of boilerplate
writing imports
$ cat <<EOF > Hello.java
public class Hello {
public static void main(String args[]) {
System.out.println("Hello world!");
}
}
EOF
$ java Hello.java
Hello world!
ok
Welcome to java, we have a couple unconventional ways of doing things, but overall I’m like every other mainstream oo language.
People: AHH! Scary!
Welcome to python. your knowledge of me wont help you elsewhere as my syntax is purposefully obtuse and unique. Forget about semicolons, one missed space and your code is as worthless as you after learning this language.
People: Hello based department
Oh my god I got fucked by a python script once because of a single space. It took forever to figure out what went wrong
I refuse to code in Python without a really good IDE and linting like PyCharm. When using PyCharm it’s very rare I have issues like this, because it catches them in one way or another, but I notice it catches those kinds of issues a lot when I’m coding soooooooo…
I have also setup the IDE to specifically color code comments like
’ # End If and ’ # Next
in the same style as their beginning statements as I find it much easier to visually scam through code when they are present.
This is getting a little better nowadays.
> cat Hello.java
void main() {
System.out.println("Hello, World!");
}
> java --enable-preview Hello.java
Hello, World!
Things to notice:
- No compilation step.
- No class declaration.
- Main method is not
public static - No
String[] args.
This still uses preview features though. However, like you demonstrated already, compilation is no longer a required step for simplistic programs like this.
Main method is not public static
It must be somewhere under the hood. Otherwise, it wont be callable and it would require an instance of an object to call. Unless the object here is the Java environment?
No String[] args
They are just optional I’m sure, like C and C++. You still need them to read command line arguments.
All in all, these syntax improvements are welcome. I already moved on to Kotlin for Android development though.
Main method is not public static
It must be somewhere under the hood. Otherwise, it wont be callable and it would require an instance of an object to call. Unless the object here is the Java environment?
No. From JEP-445:
If an unnamed class has an instance main method rather than a static main method then launching it is equivalent to the following, which employs the existing anonymous class declaration construct:
new Object() { // the unnamed class's body }.main();
No String[] args
They are just optional I’m sure, like C and C++. You still need them to read command line arguments.
Without the preview feature enabled, it is not an optional part of the method signature. It specifically looks for a main(String[]) signature.
Microsoft Java is a one-liner these days.
> cat program.cs
Console.WriteLine("Hello, World!");
> dotnet run
Hello, World!
C:
#include <stdio.h>
int main() {
printf("Hello World!");
return(0);
}
EDIT: POSIX-compatible shell:
echo "Hello World!"
Python2 is only one character longer:
print “Hello world!”
And you get proper data types too.
