Problem : Write a program that takes a name from command line and say hello it? If no name is passed then display a user friendly Usage message.

Contents

1. 1 Program :
   1. 1.1 Step 1 - Coding
   2. 1.2 Step 2 - Deployment
   3. 1.3 Step 3 - Testing
   4. 1.4 Output

Program :

Step 1 - Coding

Create a text file c:\sunilos\HelloName1.java  and copy below contents.

/*
 * A program which take commond line argument and check error.
 */
public class HelloName1 {

    public static void main(String[] args) {

                //Check length of an array.  If an argument will be passed then length will be one
        if (args.length == 1) {
            System.out.println("Hello " + args[0]);
        } else {
            System.out.println("Usage : java -cp c:/sunilos HelloName1");
        }

    }
}

Step 2 - Deployment

1. Create a folder 'c:\sunilos'. 
2. Create or copy HelloName1.java  into 'c:\sunilos' folder.
3. Open your command prompt and go to  'c:\sunilos'
   
4. Compile HelloName1.java with help of 
• javac HelloName1.java command.Command will create class file in the same folder.
5. Congratulations!! your Java program is ready to serve.

Step 3 - Testing

1. Make sure you are on Command Prompt under c:\sunilos directory
   
2. Now start your java program from command prompt with help of
   
• java HelloName1 SunilOS
3. Now again execute java program from command prompt without any argument
   
• java HelloName1
  

Output

With argument
Hello SunilOS

Without argument
Usage : java -cp c:/sunilos HelloName1


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