Prog_1/Tries/Shell.java

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

/**
 * Main Class for the Student-Administration.<br />
 * The user types commands and parameters to manipulate or change
 * the Trie. <br />Commands are found with the HELP command
 */
final class Shell {
    private Shell() { }
    /**
     * Checks if <code>string</code> consists of only chars.
     * @param string String to check
     * @return <code>true</code>, if <code>string</code> has only chars<br />
     *          <code>false</code>, if <code>string</code> has other signs
     */
    private static boolean isCharString(String string) {
        for (int j = 0; j < string.length(); j++) {
            if (string.charAt(j) - 'a' < 0
                   || string.charAt(j) - 'a' > 25) {
                return false;
            }
        }
        return true;
    }

    /**
     * Main method for the Student Administration including the Shell.
     * Validation for input.
     * @param args are not handled at the moment
     * @throws IOException
     */
    public static void main(String[] args) throws IOException {
        Trie t = new Trie();
        boolean runtime = true;
        BufferedReader br = new BufferedReader(
                new InputStreamReader(System.in));
        while (runtime) {
            System.out.print("trie> ");
            String input = br.readLine();
            String[] splited = input.split(" ");
            char ch = splited[0].charAt(0);
            ch = Character.toLowerCase(ch);
            try {
            switch(ch) {
            case 'n' :
                if (splited.length != 1) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                t = new Trie();
            break;
            case 'a' :
                if (splited.length != 3) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!isCharString(splited[1])) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (Integer.parseInt(splited[2]) < 0) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!t.add(splited[1], Integer.parseInt(splited[2]))) {
                    System.out.println("Error! " + splited[1]
                                       + " is already present.");
                }
            break;
            case 'c' :
                if (splited.length != 3) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!isCharString(splited[1])) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (Integer.parseInt(splited[2]) < 0) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!t.change(splited[1], Integer.parseInt(splited[2]))) {
                    System.out.println("Error! " + splited[1]
                                            + " does not yet exist");
                }
            break;
            case 'd' :
                if (splited.length != 2) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!isCharString(splited[1])) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!t.delete(splited[1])) {
                    System.out.println("Error! " + splited[1]
                           + " does not yet exist");
                }
            break;
            case 'p' :
                if (splited.length != 2) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (!isCharString(splited[1])) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                if (t.points(splited[1]) != null) {
                    System.out.println(t.points(splited[1]));
                } else {
                    System.out.println("Error! " + splited[1]
                           + " does not yet exist");
                }

            break;
            case 't' :
                if (splited.length != 1) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                System.out.println(t.toString());
            break;
            case 'h' :
                if (splited.length != 1) {
                    System.out.println("Error! Wrong Parameter! "
                            + "check HELP");
                    break;
                }
                System.out.println("NEW       Creates a new empty Trie ");
                System.out.println("ADD       adds <name> with <points>");
                System.out.println("CHANGE    change <points> of <name>");
                System.out.println("DELETE    deletes <name>");
                System.out.println("POINTS    displays points of <name>");
                System.out.println("TRIE      displays hole Trie");
                System.out.println("HELP      display this help");
                System.out.println("QUIT      exit Shell");
            break;
            case 'q' :
                if (splited.length != 1) {
                    System.out.println("Error! Wrong Parameter! check HELP");
                    break;
                }
                runtime = false;
            break;
            default :
                System.out.println("Error! Wrong command check HELP");
            }
        } catch (NumberFormatException e) {
            System.out.println("Error! Wrong Parameter! check HELP");
        }
        }
    }
}