RandomGenerator

import java.util.ArrayList;
/*
 * File Name: RandomGenerator.java
 * Package Name: N/A
 * Application Name: Random String Generator
 *
 * Version Info: 1.0.0
 * Version Date: 09-09-2014
 *
 * Creator: Corey D. Eacret
 * Website: http://www.appdappdev.com
 * Contact: appdapp@gmail.com
 *
 * Description:
 * This is the class for the Random String Generator that actually creates the random
 * strings. It contains 3 nested classes that produce a random single digit integer,
 * random upper or lower case alpha character, or one of a list of approved symbols.
 * The class will output an ArrayList with each index containing one of the randomly
 * generated characters.
 *
 */

public class RandomGenerator {

    // We start by declaring the length and type variables, which we get from user input
    // later on in the program.
    char randType = 'a';
    int randLength = 0;

    // This is our first nested class, the one that produces a random number.
    class numGen {
        int rNum() {
            // The actual random function, gets a number between 0 and 9.
            int rN = (int) (Math.random() * 10);
            return rN;
        }
    }

    // This is our second nested class, this one produces a random alpha character.
    class alphaGen {
        char rAlpha() {
            // We start by getting a random number, between 0 and 51.
            int rN = (int) (Math.random() * 52);
            // We then use that number to pick a random starting point, 'A' or 'a'.
            char base = (rN < 26) ? 'A':'a';
            // Finally, we use our starting point, and random number, to pick our alpha char.
            char rA = (char) (base + rN % 26);
            return rA;
        }
    }

    // Our final nested class, this one uses a list of symbols, and chooses a random one.
    class symGen {
        char rSymbol() {
            // The symbol list, this allows us to only use a select few symbols.
            char[] symList = {'!','@','#','$','%','^','&','*','(',')','-','_','=','+',',','.','<','>','/','?',';',':','`','~'};
            // We get our random value, a number between 0, and the amount of symbols.
            int rN = (int) (Math.random() * 24);
            // Finally, we use our random number to pick one of the symbols from the list.
            char rS = symList[rN];
            return rS;
        }
    }

    // Now we create a new object for each of our random generators.
    RandomGenerator.numGen getRandNum = new RandomGenerator.numGen();
    RandomGenerator.alphaGen getRandAlpha = new RandomGenerator.alphaGen();
    RandomGenerator.symGen getRandSym = new RandomGenerator.symGen();

    // This is the method that takes the user input, and then creates the random string.
    public ArrayList<String> randGenerator(int randType, int randLength) {

        // Our ArrayList which is the output at the end of this class.
        ArrayList<String> outputString = new ArrayList<String>();

        // Start of our if else list, that uses the user input to select the type of string.
        if (randType == 'a' || randType == 'A') {

            // For statement to generate a random character for the length requested.
            for (int aType=0;aType!=randLength;aType++) {

                // We use the random number generator to also create a random number that
                // we use to decide which type (num,alpha,sym) for each spot.
                String rndOutput;
                int whichType = getRandNum.rNum();

                if (whichType < 4) {
                    // Here we get a random alpha character, and convert char to string.
                    rndOutput = Character.toString(getRandAlpha.rAlpha());
                    outputString.add(rndOutput);
                }
                else if (whichType > 3 && whichType < 7) {
                    // Here we get a random number, and convert int to string.
                    rndOutput = Integer.toString(getRandNum.rNum());
                    outputString.add(rndOutput);
                }
                else if (whichType > 6) {
                    // Here we get a random symbol, and conert char to string.
                    rndOutput = Character.toString(getRandSym.rSymbol());
                    outputString.add(rndOutput);
                }
            }
        }

        // Here we get our string, if type is set to 'b'. The functions inside are the same
        // as above, so there won't be comments on the rest of these.
        else if (randType == 'b' || randType == 'B') {
            for (int aType=0;aType!=randLength;aType++) {

                String rndOutput;
                int whichType = getRandNum.rNum();

                if (whichType < 5) {
                    rndOutput = Character.toString(getRandAlpha.rAlpha());
                    outputString.add(rndOutput);
                }
                else if (whichType > 4) {
                    rndOutput = Integer.toString(getRandNum.rNum());
                    outputString.add(rndOutput);
                }
            }
        }

        // Here we get our string for 'c' type.
        else if (randType == 'c' || randType == 'C') {
            for (int aType=0;aType!=randLength;aType++) {

                String rndOutput;

                rndOutput = Character.toString(getRandAlpha.rAlpha());
                outputString.add(rndOutput);
            }
        }

        // Here we get our string for 'd' type.
        else if (randType == 'd' || randType == 'D') {
            for (int aType=0;aType!=randLength;aType++) {

                String rndOutput;

                rndOutput = Integer.toString(getRandNum.rNum());
                outputString.add(rndOutput);
            }
        }

        // Here we get our string for 'e' type.
        else if (randType == 'e' || randType == 'E' ) {
            for (int aType=0;aType!=randLength;aType++) {

                String rndOutput;

                rndOutput = Character.toString(getRandSym.rSymbol());
                outputString.add(rndOutput);
            }
        }

        // Even with error checking, we leave this in just in case funny things happen.
        else {
            System.out.println("INVALID TYPE!!");
        }

        // Here we send out our completed random string!!
        return outputString;
    }
}