Question

There are three distinct areas you need to research and focus on to get your final done properly:

• Process command line arguments to get the names of input and output files from the user using Elipse

• Read and write information from and into the disk files

• Parse the data read from input file, store in a variable, process it and then print it

  on the screen and into the output file.
  Here are couple of exercises, which will help you in writing code for the above problems.

9.1 Write a class named Exercise5. Your main method’s header looks like this:

public static void main(String[] args)
where, args is the String array of command line arguments passed by JVM. Write a

method processCLArguments() like this:

public static void processCLArguments(String[] args) if the command args contains less than two strings, it displays the message like this:

      Usage: java Exercise5 inputFile outputFile

If the arguments contains input and output file names it displays the message like this:

Input will be read from: input_final.txt Output will be written into: output_final.txt

9. 2 Write another static method called processInputOutputFiles(), which takes a String array as arguments which has names of input and output files.

    public static void processInputOutputFiles(
                                           String[] args)

It reads the content of the input file whose name is in the first element of args String array with the scores for unknown number of students like the following. The format of the data is, name of a student, followed by comma-separated scores of quiz1, quiz2, quiz3, quiz4, midterm 1, midterm 2 and final for that student:

Thui Bhu, 100, 90, 80, 100, 89, 99, 88
Ariana B. Smith, 90, 90, 100, 100, 99, 100, 95

//more students data

Read each line (scores of a student) at a time, and

a) display the output on the screen like this:

Student #: 1 Thui Bhu, 100, 90, 80, 100, 89, 99, 88
Student #: 2 Ariana B. Smith, 90, 90, 100, 100, 99, 100, 95

b) and print the output on the disk file whose name is given in the second element of args String array. The disk output looks like this:

Student #1 is: "Thui Bhu" whose raw scores are: 100: 90: 80: 100: 89: 99: 88: Student #2 is: "Ariana B. Smith" whose raw scores are: 90: 90: 100: 100: 99: 100: 95:

9.3 Research on how to give the command line arguments in your class file using Eclipse.

When starting a Java application, you may want to supply few input parameters to your application even before your program starts. For example, giving database names, supplying username and password etc.

Supplying these arguments before the application starts differs in the way you start your application. You can run your Java application through command window (Windows) or terminal window (MAC). You can even supply these arguments while running from your favorite IDE, e.g. Eclipse.

So, there are two questions:

1. a) How do you supply these arguments to your program, and

2. b) How do you process these arguments in your program

Answer 1

Hi,

Please find the java code below:

///////////////////////////////

Java code:

package exercise;

//Exercise5 class
public class Exercise5 {
   //method processCLArguments()
   public static void processCLArguments(String[] args) {
       //two arguments check
       if (args.length < 2) {
           System.out.println("Usage: java Exercise5 inputFile outputFile");
           System.exit(1);
       }
       else {
           System.out.println("Input will be read from: "+ args[0] + " Output will be written into: " + args[1]);
           System.out.println();   }
   }

   public static void main(String[] args) {
       //invoke the method
       processCLArguments(args);
   }
}

Screenshot:

We can set the command line arguments in Eclipse IDE

using Run configuration.

Right click >> Run configuration

/////////////////////////////

Let me know if you need more help on this in the comments.
HOpe this helps.