Adding the original version from the blog.

src/main/java/b1/Main.java

@@ -0,0 +1,23 @@
+package b1;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import jline.ConsoleReader;
+
+public class Main {
+
+    public static void main(String[] args) throws IOException {
+        ConsoleReader reader = new ConsoleReader();
+        String line;
+        PrintWriter out = new PrintWriter(System.out);
+        while ((line = reader.readLine("number or quit> ")) != null) {
+            if (line.equalsIgnoreCase("quit")) {
+                break;
+            }
+            int i = Integer.parseInt(line);
+            System.out.println(
+                    Math.square(i) + " ist " + i + " quadriert");
+            out.flush();
+        }
+    }
+}

src/main/java/b1/Math.java

@@ -0,0 +1,8 @@
+package b1;
+
+public class Math {
+
+    public static int square(int a) {
+        return a * a;
+    }
+}

src/test/java/b1/MathTest.java

@@ -0,0 +1,12 @@
+package b1;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class MathTest {
+
+    @Test
+    public void testSqure() {
+        Assert.assertEquals(16, Math.square(4));
+    }
+}