Committing my attempt on task number 1

Not finished, not even sure If useful at all

src/main/java/_5/_1/Util.java

@@ -0,0 +1,52 @@
+package _5._1;
+
+class Util {
+
+	// liefert die kleinste Zahl des uebergebenen Arrays
+	public static int minimum(int[] values) throws IllegalArgumentException {
+		if (values.length <= 1 || values == null) {
+			throw new IllegalArgumentException("The given array has not enough elements (<=1) or is null");
+		}
+		int min = values[0];
+		for (int i = 1; i < values.length; i++) {
+			if (values[i] < min) {
+				min = values[i];
+			}
+		}
+		return min;
+	}
+
+	// konvertiert den uebergebenen String in einen int-Wert
+	public static int toInt(String str) {
+		int result = 0, factor = 1;
+		char ch = str.charAt(0);
+		switch (ch) {
+			case '-':
+				factor = -1;
+				break;
+			case '+':
+				factor = 1;
+				break;
+			default:
+				result = ch - '0';
+		}
+		for (int i = 1; i < str.length(); i++) {
+			ch = str.charAt(i);
+			int ziffer = ch - '0';
+			result = result * 10 + ziffer;
+		}
+		return factor * result;
+	}
+
+	// liefert die Potenz von zahl mit exp,
+	// also zahl "hoch" exp (number to the power of exp)
+	public static long power(long number, int exp) throws IllegalArgumentException {
+		if(number == 0L && exp < 0){
+			throw new IllegalArgumentException("Division by zero");
+		}
+		if (exp == 0) {
+			return 1L;
+		}
+		return number * Util.power(number, exp - 1);
+	}
+}

src/main/java/_5/_1/UtilTest.java

@@ -0,0 +1,30 @@
+package _5._1;
+
+
+import provided.IO;
+
+public class UtilTest {
+
+	// Testprogramm
+	public static void main(String[] args) {
+		String eingabe = IO.readString("Zahl: ");
+		int zahl = Util.toInt(eingabe);
+		try {
+			System.out.println(zahl + " hoch " + zahl + " = "
+					+ Util.power(zahl, zahl));
+		}catch(IllegalArgumentException exc){
+			System.out.println("A exception has occurred: Division by zero");
+		}
+		try {
+			System.out.println(Util.minimum(new int[]{1, 6, 4, 7, -3, 2}));
+			System.out.println(Util.minimum(new int[0]));
+			System.out.println(Util.minimum(null));
+		} catch(IllegalArgumentException exc){
+			System.out.println("Array has not enough elements: <2");
+		}
+
+
+	}
+}
+
+