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+====== My Solution on Assignment 2 - Problem 6 ======
+This is my Solution of Assignment 2 - Problem 6 from the [[http://see.stanford.edu/see/courseinfo.aspx?coll=824a47e1-135f-4508-a5aa-866adcae1111|Computer Science Course CS106A of Prof. Mehran Sahami]] at the [[http://www.stanford.edu|STANFORD University]].
+<code java Hailstone.java>
+/*
+ * File: Hailstone.java
+ * Name: Axel Werner
+ * Section Leader:
+ * --------------------
+ * This file is the starter file for the Hailstone problem.
+ */
+import acm.program.*;
+/**
+ * Class to ask User for a integer start number to
+ * calculate Hailstone Numbers sequence.
+ * @author Axel Werner
+ */
+public class Hailstone extends ConsoleProgram {
+	/**
+	 * Main Program
+	 */
+	public void run() {
+		println("Hailstone Calculator");
+		println("===================================\n\n");
+		int input = askForNumber();
+		println("Calculating Hailstone Numbers now:\n");
+		int tmp = doCalculations(input);
+		println("Last Hailstone Number ('" + tmp + "') reached.");
+		println("I needed '" + stepsCounter + "' Steps to reach this point.\n\n");
+		println("Im done. == TERMINATED ==");
+	}
+	/**
+	 * Method to calculate the Hailstone Numbers.
+	 * It takes a single positive integer number, calculates and prints out
+	 * the Hailstone Row and then returns the last Number (1).
+	 *
+	 * @param input any positive integer number
+	 * @return Always returns 1, as is always the last Hailstone Number in a Calculation. Why that?
+	 * 			Just for readability.
+	 */
+	private int doCalculations(int input) {
+		int tmp = input;
+		while(tmp!=1){
+			stepsCounter++; // increment the Step Counter.
+			if( isEven(tmp) ){
+				int oldTmp=tmp;
+				tmp=tmp/2;
+				println( oldTmp + " is even. So i take 1/2: " + tmp );
+			}else{ // so must be Odd then...
+				int oldTmp=tmp;
+				tmp=tmp*3+1;
+				println( oldTmp + " is odd. So i make 3n+1: " + tmp );
+			}
+		}
+		return tmp;
+	}
+	/**
+	 * Method asks User for a positive integer Number and
+	 * then return it.
+	 *
+	 * @return positive integer Number given by User Input.
+	 */
+	private int askForNumber() {
+		int input = readInt("Pick a positive integer Number: ");
+		while(input<=0){
+				println("ERROR: You need to pick a POSITIVE INTEGER. Please retry.\n");
+				input = readInt("Pick a positive integer Number: ");
+		}
+		println("Thanks!\n");
+		return input;
+	}
+	/**
+	 * Method takes an integer number to test if its even.
+	 * It returns TRUE if Number is even.
+	 * Else it returns FALSE.
+	 *
+	 * @param tmp integer number to test
+	 * @return TRUE if parameter is an even Number. Else returns FALSE.
+	 */
+	private boolean isEven(int tmp) {
+		if(tmp%2!=0){
+			return false; // there is a remainder. So it must be ODD.
+		}else{
+			return true; // there is NO remainder. So it must be EVEN.
+		}
+	}
+	/**
+	 * Instance Var to keep track of the Number of Steps needed to reach 1
+	 */
+	private int stepsCounter=0;
+}
+</code>
+ --- //[[mail@awerner.homeip.net|Axel Werner]] 2012-04-02 20:30//
+{{tag>java karel stanford university cs106 computer science learning programming}}