I think you have already noticed the unusual header for the main method in Java, which has the parameter args of String[] type. Obviously, args is an array of String. The main method is just like a regular method in Java, you can call it by passing actual parameters to it. So let’s look at the below examples, this main method in TestMain is invoked by a method in A:

public class TestMain {
  public static void main(String[] args) {
    for (int i = 0; i < args.length; i++)
      System.out.println(args[i]);
  }
}

public class A {
  public static void main(String[] args) {
    String[] strings = {"New York","Boston", "Atlanta"};
      TestMain.main(strings);
  }
}

The main method is just like a regular method. Furthermore, you can pass arguments to it from the command line.

Let me show you how to display the parameters we passed to the main method from the command line:

public class CommandLineArgumentsDemo {
    public static void main(String[] args) {
        for (String arg : args) {
            System.out.println(arg);
        }
    }
}

For the CommandLineArgumentsDemo method, we do two steps to show the parameters we passed to it from the command line.

1. use javac command to compile it to TestMain.class file
2. use java command to run TestMain: java TestMain 1 2 3

The program above should display the parameters you passed to it on the console.

andrews-mbp:src andrew$ java CommandLineArgumentsDemo 1 2 3
1
2
3