import java.util.Scanner;


public class Vokalersetzung {
    /*
        Übungsblatt 1 - 14.10.2015
        Aufgabe 1.7 (H) Vokale ersetzen
    */

    public static void main(String[] args) {
        String text = "Hat der alte Hexenmeister\n"
                    + "sich doch einmal wegbegeben!\n"
                    + "Und nun sollen seine Geister\n"
                    + "auch nach meinem Willen leben.\n"
                    + "Seine Wort und Werke\n"
                    + "merkt ich und den Brauch,\n"
                    + "und mit Geisterstärke\n"
                    + "tu ich Wunder auch.\n"
                    + "Walle! walle\n"
                    + "Manche Strecke,\n"
                    + "daß, zum Zwecke,\n"
                    + "Wasser fließe\n"
                    + "und mit reichem, vollem Schwalle\n"
                    + "zu dem Bade sich ergieße.\n";  
        // all vowels (characters to be replaced) in lowercase (important!)
        char[] vowel = {'a', 'e', 'i', 'o', 'u'};
        
        // Ask for the vowel to replace the others.
        System.out.println("Mit welchem Vokal sollen die anderen Vokale ersetzt werden?");
        
        // Read replacement vowel from console (has to be a vowel!).
        int replaceWith; // the index of the vowel that replaces the others
                // (Info: Instead of simply using the entered character, which
		// would also only be a vowel when leaving the loop, the index
		// of the vowel in array (vowel) is used. There is no difference,
		// how it is done in the script. This way is only used for formal
		// reasons, but one discrete variable would be used anyway.)
        Scanner input = new Scanner(System.in); // scanner for reading from console
        Outerloop: // to exit the while loop (no separate help var required)
        while (true) {
            System.out.print("Eingabe: ");
        
            // Read string entered on the console and check length (1 = char).
            String inputString = input.next().toLowerCase();
            if (inputString.length() > 1) { 
                System.out.println("Die Eingabe ist zu lang!");
                continue; // skip the rest of the loop
            } 
            
            // Check if the entered char is one of the required ones (vowels).
            for (replaceWith = 0; replaceWith < vowel.length; replaceWith++) {
                if (inputString.charAt(0) == vowel[replaceWith]) break Outerloop;
            }
            
            // If this point is reached, something uncorrect was entered.
            System.out.println(inputString + " ist kein Vokal!");
        }
        
        // Print replacement character
        System.out.println("Vokale wurden durch " + vowel[replaceWith] + " ersetzt:");
        System.out.println(); // blank line
        
        // Replace characters (upper and lower case)
        for (int i = 0; i < vowel.length; i++) {
            if (i != replaceWith) { // vowel does not need to replace itself
                text = text.replace(vowel[i], vowel[replaceWith]);
                text = text.replace(Character.toUpperCase(vowel[i]), 
                                    Character.toUpperCase(vowel[replaceWith]));
            }
        }
        
        System.out.println(text); // Print new text
    }
    
}