Main Method

Since your very first Java program you've written this method:

public static void main(String[] args) {
}

* We know this special method is what Java looks for as the starting point for running your program, but what about that String[] args?

Drill¶

ArgsArray/src/drills/

In the drills folder create a new Java program, ShowMe.java and give it a main method. * In main add:

System.out.println(args);

and run the program.

Practice Exercise¶

When you print the reference value for an array, you'll see something like: * [Ljava.lang.String;@3d4eac69 * [ means it's an array reference. * L means the elements of the array are objects of a cLass. * java.lang.String; is the class of objects the array holds. * @3d4eac69 is ... well, never mind for now.

To understand args we need to go back to the command line.

Drill¶

Open a terminal and navigate to the Eclipse project folder for this section.

cd ~/SD/Java/workspace/   # Go to the workspace directory
ls                        # list the files and folders here
cd ArgsArray/             # Go to the project folder for this section
find .                    # Find and print the name of everything in and under the current directory.
cd bin/                   # This is where Eclipse puts compiled classes.

Were going to run our ShowMe program from the command line:

java drills.ShowMe

As we modify ShowMe.java in Eclipse and save, Eclipse compiles our changes and recreates drills/ShowMe.class, which we'll run in our terminal with java drills.ShowMe.

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