Adding the original version from the blog.

.gitignore

@@ -4,3 +4,4 @@
 *.jar
 *.war
 *.ear
+/target/

pom.xml

@@ -11,20 +11,24 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <build>
         <plugins>
             <plugin>
-                <groupId>
+                <groupId>org.antlr</groupId>
-                    org.apache.maven.plugins
+                <artifactId>antlr3-maven-plugin</artifactId>
-                </groupId>
+                <version>3.1.3-1</version>
-                <artifactId>
+                <executions>
-                    maven-compiler-plugin
+                    <execution>
-                </artifactId>
+                        <goals>
+                            <goal>antlr</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
                 <version>2.1</version>
                 <configuration>
-                    <source>
+                    <source>1.5</source>
-                        1.5
+                    <target>1.5</target>
-                    </source>
-                    <target>
-                        1.5
-                    </target>
                     <encoding>UTF-8</encoding>
                 </configuration>
             </plugin>
@@ -62,6 +66,12 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
             <artifactId>jline</artifactId>
             <version>0.9.9</version>
         </dependency>
+        <dependency>
+            <groupId>org.antlr</groupId>
+            <artifactId>antlr-runtime</artifactId>
+            <version>3.2</version>
+            <type>jar</type>
+        </dependency>
     </dependencies>
     <repositories>
         <repository>

src/main/antlr3/package/b1/b1.g

@@ -0,0 +1,37 @@
+// Name der Grammatik
+grammar b1;
+
+// einfache, feste Tokens
+tokens {
+	PLUS 	= '+' ;
+	MINUS	= '-' ;
+	MULT	= '*' ;
+	DIV	= '/' ;
+}
+
+@header {
+        package b1;
+}
+
+@lexer::header {
+        package b1;
+}
+
+ausdruck:
+        term ( ( PLUS | MINUS )  term )* ;
+
+term	:
+        faktor ( ( MULT | DIV ) faktor )* ;
+
+faktor	:
+        ZAHL ;
+
+ZAHL	:
+        (DIGIT)+ ;
+
+WHITESPACE :
+        ( '\t' | ' ' | '\r' | '\n'| '\u000C' )+
+                { $channel = HIDDEN; } ;
+
+fragment DIGIT	:
+        '0'..'9' ;

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));
+    }
+}