[New] Added RoundRobinInt with test

li.strolch.utils/src/main/java/li/strolch/utils/RoundRobinInt.java

@@ -0,0 +1,23 @@
+package li.strolch.utils;
+
+public class RoundRobinInt {
+	private int start;
+	private int stop;
+	private int index;
+
+	public RoundRobinInt(int start, int stop) {
+		if (start >= stop)
+			throw new IllegalArgumentException(
+					"A round robin start >= stop does not make sense: " + start + " >= " + stop);
+		this.start = start;
+		this.stop = stop;
+		this.index = start;
+	}
+
+	public int next() {
+		int next = this.index++;
+		if (this.index > this.stop)
+			this.index = this.start;
+		return next;
+	}
+}

li.strolch.utils/src/test/java/li/strolch/utils/RoundRobinIntTest.java

@@ -0,0 +1,45 @@
+package li.strolch.utils;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class RoundRobinIntTest {
+
+	@Test
+	public void shouldDoRoundRobin0_2() {
+		RoundRobinInt rr = new RoundRobinInt(0,2);
+		assertEquals(0, rr.next());
+		assertEquals(1, rr.next());
+		assertEquals(2, rr.next());
+		assertEquals(0, rr.next());
+		assertEquals(1, rr.next());
+		assertEquals(2, rr.next());
+	}
+	@Test
+	public void shouldDoRoundRobin1_2() {
+		RoundRobinInt rr = new RoundRobinInt(1,2);
+		assertEquals(1, rr.next());
+		assertEquals(2, rr.next());
+		assertEquals(1, rr.next());
+		assertEquals(2, rr.next());
+	}
+	@Test
+	public void shouldDoRoundRobinNeg10_2() {
+		RoundRobinInt rr = new RoundRobinInt(-10,2);
+		assertEquals(-10, rr.next());
+		assertEquals(-9, rr.next());
+		assertEquals(-8, rr.next());
+		assertEquals(-7, rr.next());
+		assertEquals(-6, rr.next());
+		assertEquals(-5, rr.next());
+		assertEquals(-4, rr.next());
+		assertEquals(-3, rr.next());
+		assertEquals(-2, rr.next());
+		assertEquals(-1, rr.next());
+		assertEquals(0, rr.next());
+		assertEquals(1, rr.next());
+		assertEquals(2, rr.next());
+		assertEquals(-10, rr.next());
+	}
+}