diff --git a/checkstyle.xml b/checkstyle.xml
index 1cec088..0c17f24 100644
--- a/checkstyle.xml
+++ b/checkstyle.xml
@@ -44,7 +44,7 @@
-
+
@@ -55,13 +55,14 @@
-
+
+
+
+ value="LITERAL_TRY, LITERAL_CATCH, LITERAL_FINALLY, LITERAL_DO, LITERAL_IF, LITERAL_ELSE"/>
diff --git a/src/main/java/de/hsel/spm/baudas/analysis/Attribute.java b/src/main/java/de/hsel/spm/baudas/analysis/Attribute.java
index 375714b..e6d9883 100644
--- a/src/main/java/de/hsel/spm/baudas/analysis/Attribute.java
+++ b/src/main/java/de/hsel/spm/baudas/analysis/Attribute.java
@@ -1,11 +1,13 @@
package de.hsel.spm.baudas.analysis;
/**
+ * Indexes for all attributes.
+ *
* @author Johannes Theiner
* @version 0.1
* @since 0.1
**/
-public class Attribute {
+class Attribute {
static final int SEX = 0;
static final int AGE = 1;
diff --git a/src/main/java/de/hsel/spm/baudas/analysis/Cluster.java b/src/main/java/de/hsel/spm/baudas/analysis/Cluster.java
index 10e25b1..f98989c 100644
--- a/src/main/java/de/hsel/spm/baudas/analysis/Cluster.java
+++ b/src/main/java/de/hsel/spm/baudas/analysis/Cluster.java
@@ -1,5 +1,6 @@
package de.hsel.spm.baudas.analysis;
+import org.jetbrains.annotations.NotNull;
import weka.clusterers.SimpleKMeans;
import weka.core.Instances;
import weka.filters.Filter;
@@ -31,51 +32,51 @@ public class Cluster implements Analysis