What is the meaning of the following line in the program in Listing 1.1? n1 = keyboard.nextInt(); Write a complete Java program that uses System.out.println to display the following to the screen...

What is the meaning of the following line in the program in Listing 1.1?

n1 = keyboard.nextInt();

Write a complete Java program that uses System.out.println to display

the following to the screen when the program is run:

Hello World!

Your program does nothing else. Note that you do not need to fully

understand all the details of the program in order to write it. You can

simply follow the model of the program in listing 1.1. (You do want

to understand all the details eventually, but that may take a few more

chapters.)