CMPU 102 Lab 3: Creating and using a simple instantiable class
February 13th, 2017


Part I: Creating a class to represent a person

1.  Log in to your CS account and change directory to cs102.

2.  Change directory into your labs subdirectory.

3.  Create a new directory in your labs directory for lab 3 by entering:

          mkdir lab3

4.  Write a class to represent the physical entity we call a person. 
    Call the class Person and the file Person.java

    a)  Define the following instance members in class Person:

        fullName (String)
        age (int)
        gender (char)
        idNumber (int)

    b)  Define the following class member:

               static int counter = 9000;

    c)  Define a 3-parameter constructor for your Person class that will 
        initialize the fullName, age, and gender instance members by setting 
        them equal to three input parameters. It is only necessary to include 
        a single constructor in this class.

        Inside the constructor, increment the static counter variable and set 
        the idNumber instance variable to the value of the counter after 
        incrementing the counter. This will assign each Person object you 
        created a different numeric value starting with 9001 and increasing 
        in the order in which the objects are created.

    d)  Create public getter methods for data fields 1 through 4. Call
        these methods getFullName(), getAge(), getGender(), and getIDNumber().
        They should each return the value of the field type they refer to.

    e)  Lastly, create a public method called "toString" that takes no 
        input and returns a concatenated String representation of all 
        the data members.

        The String returned by the toString() method should look 
        something like this (use the tab escape sequence (\t) for tabs 
        between data fields):

           Person 1:  Harvey Jones    14     M 

           // note: 4 variable names are used in this output,
           // concatenated with "Person " and ": " in the indicated
           // positions.

    NOTE: COMPILE AND SAVE OFTEN.  YOU WILL NOT BE ABLE TO RUN THE 
          PERSON.JAVA FILE UNTIL AFTER YOU FINISH PART II.      
          
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Part II: Testing the class from part I

    Write a procedural application TestPerson in a file called 
    TestPerson.java

    This tester program should have a main method in which you should:

     1. Prompt for and then read user input from the keyboard to create
        two Person objects (instantiation in step 2, below), e.g.,

        java.util.Scanner rd = new java.util.Scanner(System.in);

        System.out.println("Please enter the full name of person 1:");
        String name1 = rd.next();
        System.out.println("Please enter the age of person 1:");
        int age1 = rd.nextInt();
        System.out.println("Please enter the gender of person 1 (F/M/T:");
        char gender1 = (rd.next().charAt(0));

        You will need another set of the statements like the ones given
        above to create the second person. 

     2. Use the keyword "new" and call the 3-parameter constructor written in 
        the Person class to instantiate each Person instance. 

     3. call the toString method of each object within a System.out.println 
        statement to print all data fields for each object, and

     4. print the total number of objects created by accessing the static 
        counter in the Person class, Person.counter.

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    The output from the tester program should look like this (with your own
    choices for names, etc.):

           Person 1:  Harvey Jones     14     M   // these 2 lines are from          
           Person 2:  Wanda Schultz    36     F   // calls to toString()

           Total people = 2    // This is a separate print statement.      
          

Show your files to your professor or a coach and get checked off when you 
are finished and have tested your programs. 

Don't forget to log out.