A simple program that gets a String input from the user and prints a statement with the input variable. By this program, you can understand taking inputs from user and printing variables and user-defined method.

Task: Get the user's name from the user and print "Welcome to your workstation Name"

The filename must have the same name as the public class name, This is to ensure that the Java Virtual Machine (JVM) understands the entry point of the program

To run the program, open your commandline and type the following:

• Without Commandline Arguments

 $ ..\JavaBasic> javac .\GreetUser\GreetUser.java
 $ ..\JavaBasic> java GreetUser.GreetUser

• With Commandline Arguments

 $ ..\JavaBasic> javac .\GreetUser\GreetUser.java
 $ ..\JavaBasic> java GreetUser.GreetUser "Kode-Logger"

  package GreetUser;

  import java.util.Scanner; // Scanner class is requied to get user inputs 

  public class GreetUser {
      public static void main(String[] args) {
          if (args.length > 0){ // checks for commandline arguments...
              greet(args[0]); // calls greet("") method
          }
          else { // if user didn't give any commandline arguments ...
              System.out.print( "Enter your Name: " ); // Prints the text: Enter your Name
              Scanner scan = new Scanner ( System.in ); // scan is an object of Scanner
              String name = scan.nextLine (); // name gets the user input
              scan.close (); // closes the "System.in" input stream
              greet(name); // calls greet("") method
          }
    }

    public static void greet(String username){
        System.out.println ( "Welcome to your workstation " + username + "." ); // prints the statement given
    }
}

import java.util.Scanner; : imports Scanner class from java > util package. Scanner is a class that lets you get user input form the user. Scanner can take any primitive data type as input from the user.

public static void main(String[] args) : main method/function is the first method that will be executed in any java programs.

String[] args : args is a array of String type. It is used to get commandline arguments for your program.

args.length > 0 : checks whether args is empty or not

greet(args[0]); : calls greet() method with first-argument (args[0]) as parameter

System.out.println(); : Prints the String and changes output cursor to next line

Scanner scan = new Scanner ( System.in ); : scan is an object(a special variable that stores the address in RAM/main memory) of the class Scanner. Here scan acts as the variable that has the access to System.in stream (An input stream that connects keyboard input to the program.

scan.nextLine() : gets a line from user input which can contain spaces and multiple words.

scan.close(); : closes the input stream link/pipe.

public static void greet(String username) : user defined method.