A String Demo/Lab

• I wrote this Java class to show common String functions.
• Some lines continue on to the next line due to the width of your display.  For this to work properly, please make all statements one line.
/*
 * StringManip.java
 *
 * Created on January 7, 2002, 11:15 PM
 */

/**
 *
 * class StringManip
 *
 * Shows off some of the valuable String manipulation functions.
 *
 * @author  jonesbr@email.uc.edu
 * @version 1.0.0
 */
public class StringManip {

    // Some variables we will use throughout this program.
    // These are private, meaning they can only be changed by this class itself.
    private int firstNumber = 1;
    private int secondNumber = 2;
    private char firstChar = 'a';
    private String myString = "This is the string I shall manipulate.";
 
    /**
     * StringManip(String args[])
     *
     * The constructor of the StringManip object.  This method runs when a new
     * StringManip object is created.
     *
     * args[] is the String array of command line arguments.
     *
     * Based on the length of args[], or the number of Strings in args[], the
     * constructor (re) sets the values of the private variables above.
     *
     * Note: In general, I strongly recommend NOT using switch-case.  It just
     * so happens that this is one of the rare times when switch-case is a good
     * fit.
     *
     */
 
    public StringManip(String args[]) {
        // Use the length of the args array to determine which variables to set
        // from user input.
        switch (args.length) {
            case 4:
                firstChar = args[3].toCharArray()[0];
            case 3:
                secondNumber = Integer.parseInt(args[2].trim());
            case 2:
                firstNumber = Integer.parseInt(args[1].trim());
            case 1:
                myString = args[0];
        }
    }
 
    /**
     * evaluate runs methods on the given variables and prints the data to
     * the standard output via System.out.println().
     *
     * jonesbr@email.uc.edu
     * January 7, 2002
     *
     */
 
    public void evaluate() {
        System.out.println("The String length is: " + myString.length());
        System.out.print("The substring generated by starting position " + firstNumber);
        System.out.print(" and ending position " + secondNumber + " is: ");
        System.out.println(myString.substring(firstNumber, secondNumber));
        System.out.println("The position of character " + firstChar + " is: " + myString.indexOf(firstChar));
        System.out.println("The character at position " + secondNumber + " is: " + myString.charAt(secondNumber));
    }
 
    /**
     * public static void main(String args[])
     *
     * This method is called from the command line to start the program.
     * The command line arguments are inserted into the args[] String array.
     * Each String, separated by spaces, will be a new element in the array.
     *
     * The first line gives the usage of the class.  In other words, it tells what
     * arguments can be passed.  This is common for command line programs, though
     * it is usually only printed when incorrect parameters are entered.
     *
     * To properly use this class, a new object must be instantiated.  This is the
     * job of the second line.
     *
     * Once the object is instantiated, and only then, can the evaluate() method run.
     *
     * jonesbr@email.uc.edu
     * January 7, 2002
     *
     */
 
    public static void main(String args[]) {
        System.out.println("Usage: [String_to_manipulate] [firstIndex] [secondIndex] [character]");
        StringManip stringManip = new StringManip(args);
        stringManip.evaluate();
 
 
    }

}
 
 

• If I simply compile and run this in Forte' without arguments, the output is:

Usage: [String_to_manipulate] [firstIndex] [secondIndex] [character]
The String length is: 38
The substring generated by starting position 1 and ending position 2 is: h
The position of character a is: 23
The character at position 2 is: i
 
• However, when I put these arguments in:  30-IT-396 0 5 9 this is what I get:

Usage: [String_to_manipulate] [firstIndex] [secondIndex] [character]
The String length is: 9
The substring generated by starting position 0 and ending position 5 is: 30-IT
The position of character 9 is: 7
The character at position 5 is: -
 

Created by:  Brandan Jones January 4, 2002