How to make System.out.println() shorter

void p(String l){
System.out.println(l);
}

Shortest. Go for it.

Logging libraries

You could use logging libraries instead of re-inventing the wheel. Log4j for instance will provide methods for different messages like info(), warn() and error().

Homemade methods

or simply make a println method of your own and call it:

void println(Object line) {
    System.out.println(line);
}

println("Hello World");

IDE keyboard shortcuts

IntelliJ IDEA and NetBeans:

you type sout then press TAB, and it types System.out.println() for you, with the cursor in the right place.

Eclipse:

Type syso then press CTRL + SPACE.

Other

Find a "snippets" plugin for your favorite text editor/IDE

Static Import

import static java.lang.System.out;

out.println("Hello World");

Explore JVM languages

Scala

println("Hello, World!")

Groovy

println "Hello, World!" 

Jython

print "Hello, World!" 

JRuby

puts "Hello, World!" 

Clojure

(println "Hello, World!")

Rhino

print('Hello, World!'); 

Java is a verbose language.

If you are only 3 days in, and this is already bothering you, maybe you'd be better off learning a different language like Scala:

scala> println("Hello World")
Hello World

In a loose sense, this would qualify as using a "library" to enable shorter expressions ;)