Java Applications

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main()

main() is a method that starts any Java application.

Arguments

Arguments are passed as follows;

java ProgramName arg1 arg2 "a string arg" 

Try coding the example. The filename must the same as the class name, ArgumentText, with a .java suffix. Use javac ArgumentText.java to create ArgumentText.class.

class ArgumentTest {
   public static void main(String[] arguments) {
      for (int i=0; i < arguments.length;i++) {
           System.out.println("Argument " + i + ":" + arguments[i]);
       }
   }
}

Run this application by entering in DOS or UNIX

java ArgumentTest arg1 arg2 "string in arg"

You will see:

Argument 0: arg1
Argument 1: arg2
Argument 2: arg3

Example

I have written this program to show the concepts involving methods, arguments, classes. Run this program with different names, and see that the program correctly identifies good customers. In practice, the list of good customers would be obtained from a database query.

import java.lang.*;
class Customer {
   public boolean goodCustomer(String customerName) {
         String[] goodCustomer = { "Joe Harris", "Bob Francis"}; // Could be from a database query
         for (int i=0;i < goodCustomer.length;i++) {
                     if (customerName.compareTo(goodCustomer[i]) == 0) {
                         return true;
                      }
         }
         return false;

   }
   public static void main(String[] arguments) {
      for (int i=0; i < arguments.length;i++) {
           System.out.println("Argument " + i + ":" + arguments[i]);
       }
       Customer thisCustomer = new Customer();
       for (int i=0;i < arguments.length;i++) {
              if (thisCustomer.goodCustomer(arguments[i])) {
               System.out.println("good name" + arguments[i]); 
           } 
       }
   }
}