diff --git a/src/main/java/de/dmi3y/behaiv/kernel/Kernel.java b/src/main/java/de/dmi3y/behaiv/kernel/Kernel.java
index d261798..ec414f5 100644
--- a/src/main/java/de/dmi3y/behaiv/kernel/Kernel.java
+++ b/src/main/java/de/dmi3y/behaiv/kernel/Kernel.java
@@ -11,6 +11,7 @@
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.List;
 
 public abstract class Kernel {
 
@@ -32,12 +33,12 @@ public void setId(String id) {
 
 
     //list<features>, label
-    protected ArrayList<Pair<ArrayList<Double>, String>> data = new ArrayList<>();
+    protected List<Pair<List<Double>, String>> data = new ArrayList<>();
 
 
     public abstract boolean isEmpty();
 
-    public abstract void fit(ArrayList<Pair<ArrayList<Double>, String>> data);
+    public abstract void fit(List<Pair<List<Double>, String>> data);
 
     public void fit() {
         fit(this.data);
@@ -51,18 +52,18 @@ public boolean readyToPredict() {
         return data.size() > treshold;
     }
 
-    public void update(ArrayList<Pair<ArrayList<Double>, String>> data) {
+    public void update(List<Pair<List<Double>, String>> data) {
     }
 
     public boolean isPartialFitAllowed() {
         return partialFitAllowed;
     }
 
-    public void updateSingle(ArrayList<Double> features, String label) {
+    public void updateSingle(List<Double> features, String label) {
         data.add(new Pair<>(features, label));
     }
 
-    public abstract String predictOne(ArrayList<Double> features);
+    public abstract String predictOne(List<Double> features);
 
     public boolean isAlwaysKeepData() {
         return alwaysKeepData;
@@ -80,7 +81,7 @@ public void save(BehaivStorage storage) throws IOException {
     }
 
     public void restore(BehaivStorage storage) throws IOException {
-        final TypeReference<ArrayList<Pair<ArrayList<Double>, String>>> typeReference = new TypeReference<ArrayList<Pair<ArrayList<Double>, String>>>() {
+        final TypeReference<List<Pair<List<Double>, String>>> typeReference = new TypeReference<List<Pair<List<Double>, String>>>() {
         };
         try (final BufferedReader reader = new BufferedReader(new FileReader(storage.getDataFile(id)))) {
             final String content = reader.readLine();
diff --git a/src/main/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernel.java b/src/main/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernel.java
index 2ae1cb6..5205d25 100644
--- a/src/main/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernel.java
+++ b/src/main/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernel.java
@@ -40,7 +40,7 @@ public boolean isEmpty() {
 
 
     @Override
-    public void fit(ArrayList<Pair<ArrayList<Double>, String>> data) {
+    public void fit(List<Pair<List<Double>, String>> data) {
         this.data = data;
         labels = toDistinctListOfPairValues(data);
         if (readyToPredict()) {
@@ -86,12 +86,12 @@ public boolean readyToPredict() {
     }
 
     @Override
-    public void updateSingle(ArrayList<Double> features, String label) {
+    public void updateSingle(List<Double> features, String label) {
         super.updateSingle(features, label);
     }
 
     @Override
-    public String predictOne(ArrayList<Double> features) {
+    public String predictOne(List<Double> features) {
 
 
         final double[] doubles = ArrayUtils.toPrimitive(features.toArray(new Double[0]));
@@ -153,7 +153,7 @@ public void restore(BehaivStorage storage) throws IOException {
         }
 
         try (final BufferedReader reader = new BufferedReader(new FileReader(storage.getNetworkMetadataFile(id)))) {
-            final TypeReference<ArrayList<String>> typeReference = new TypeReference<ArrayList<String>>() {
+            final TypeReference<List<String>> typeReference = new TypeReference<List<String>>() {
             };
             final String labelsData = reader.readLine();
             if (labelsData == null) {
diff --git a/src/main/java/de/dmi3y/behaiv/provider/Provider.java b/src/main/java/de/dmi3y/behaiv/provider/Provider.java
index e6320d7..aecd8d6 100644
--- a/src/main/java/de/dmi3y/behaiv/provider/Provider.java
+++ b/src/main/java/de/dmi3y/behaiv/provider/Provider.java
@@ -10,10 +10,10 @@
  */
 public interface Provider {
 
-    public List<String> availableFeatures();
+    List<String> availableFeatures();
 
-    public Observable<List<Double>> subscribeFeatures();
+    Observable<List<Double>> subscribeFeatures();
 
-    public Single<List<Double>> getFeature();
+    Single<List<Double>> getFeature();
 
 }
diff --git a/src/main/java/de/dmi3y/behaiv/provider/ProviderCallback.java b/src/main/java/de/dmi3y/behaiv/provider/ProviderCallback.java
index 465747e..9ad9836 100644
--- a/src/main/java/de/dmi3y/behaiv/provider/ProviderCallback.java
+++ b/src/main/java/de/dmi3y/behaiv/provider/ProviderCallback.java
@@ -6,5 +6,5 @@
 
 public interface ProviderCallback {
 
-    public void onFeaturesCaptured(List<Pair<Double, String>> features);
+    void onFeaturesCaptured(List<Pair<Double, String>> features);
 }
diff --git a/src/main/java/de/dmi3y/behaiv/storage/BehaivStorage.java b/src/main/java/de/dmi3y/behaiv/storage/BehaivStorage.java
index e80bdd3..c8ee5b1 100644
--- a/src/main/java/de/dmi3y/behaiv/storage/BehaivStorage.java
+++ b/src/main/java/de/dmi3y/behaiv/storage/BehaivStorage.java
@@ -5,12 +5,12 @@
 
 public interface BehaivStorage {
 
-    public boolean containsNetworkFile(String id);
+    boolean containsNetworkFile(String id);
 
-    public File getDataFile(String id) throws IOException;
+    File getDataFile(String id) throws IOException;
 
-    public File getNetworkFile(String id) throws IOException;
+    File getNetworkFile(String id) throws IOException;
 
-    public File getNetworkMetadataFile(String id) throws IOException;
+    File getNetworkMetadataFile(String id) throws IOException;
 
 }
diff --git a/src/main/java/de/dmi3y/behaiv/tools/DataMappingUtils.java b/src/main/java/de/dmi3y/behaiv/tools/DataMappingUtils.java
index 1a963f2..a66f278 100644
--- a/src/main/java/de/dmi3y/behaiv/tools/DataMappingUtils.java
+++ b/src/main/java/de/dmi3y/behaiv/tools/DataMappingUtils.java
@@ -15,9 +15,9 @@ private DataMappingUtils() {
     }
 
 
-    public static List<String> toDistinctListOfPairValues(List<Pair<ArrayList<Double>, String>> data) {
+    public static List<String> toDistinctListOfPairValues(List<Pair<List<Double>, String>> data) {
         Set<String> setOfValues = new HashSet<>();
-        for(Pair<ArrayList<Double>, String> arrayListStringPair : data ) {
+        for(Pair<List<Double>, String> arrayListStringPair : data ) {
             setOfValues.add(arrayListStringPair.getValue());
         }
         return new ArrayList<>(setOfValues);
@@ -31,10 +31,10 @@ public static ArrayList<Double> toListOfPairKeys(List<Pair<Double, String>> feat
         return doubleArrayList;
     }
 
-    public static double[][] toInput2dArray(List<Pair<ArrayList<Double>, String>> data) {
+    public static double[][] toInput2dArray(List<Pair<List<Double>, String>> data) {
         double[][] input2dArray = new double[data.size()][];
         int i = 0;
-        for(Pair<ArrayList<Double>, String> dataPair : data) {
+        for(Pair<List<Double>, String> dataPair : data) {
             double[] doubleArray = ArrayUtils.toPrimitive(dataPair.getKey().toArray(new Double[0]));
             input2dArray[i] = doubleArray;
             i++;
diff --git a/src/test/java/de/dmi3y/behaiv/LibraryTest.java b/src/test/java/de/dmi3y/behaiv/LibraryTest.java
index 4f2084f..cd00e28 100644
--- a/src/test/java/de/dmi3y/behaiv/LibraryTest.java
+++ b/src/test/java/de/dmi3y/behaiv/LibraryTest.java
@@ -11,6 +11,7 @@
 import org.junit.Test;
 
 import java.util.ArrayList;
+import java.util.List;
 
 import static de.dmi3y.behaiv.kernel.KernelTest.WORK;
 import static org.junit.Assert.assertEquals;
@@ -19,7 +20,7 @@ public class LibraryTest {
     Behaiv behaiv;
     private TestSleepProvider positionProvider;
     private TestSleepProvider timeProvider;
-    private ArrayList<Pair<ArrayList<Double>, String>> data;
+    private List<Pair<List<Double>, String>> data;
 
     public static final String WORK_SCREEN = "WORK_SCREEN";
 
@@ -35,8 +36,8 @@ public void setUp() throws Exception {
 
     @Test
     public void behaivTest_basicTestFlow_predictsJob() throws Exception {
-        for (Pair<ArrayList<Double>, String> fToL : data) {
-            ArrayList<Double> features = fToL.getKey();
+        for (Pair<List<Double>, String> fToL : data) {
+            List<Double> features = fToL.getKey();
             timeProvider.next(new Double[]{features.get(0)});
             positionProvider.next(new Double[]{features.get(1), features.get(2)});
             capture(fToL.getValue());
diff --git a/src/test/java/de/dmi3y/behaiv/kernel/KernelTest.java b/src/test/java/de/dmi3y/behaiv/kernel/KernelTest.java
index 116f186..78cde5f 100644
--- a/src/test/java/de/dmi3y/behaiv/kernel/KernelTest.java
+++ b/src/test/java/de/dmi3y/behaiv/kernel/KernelTest.java
@@ -10,6 +10,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.List;
 
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
@@ -39,8 +40,8 @@ public void setUp() throws Exception {
     @Test
     public void setTreshold() {
         dummyKernel.setTreshold(1L);
-        dummyKernel.data.add(new Pair<ArrayList<Double>, String>(null, null));
-        dummyKernel.data.add(new Pair<ArrayList<Double>, String>(null, null));
+        dummyKernel.data.add(new Pair<List<Double>, String>(null, null));
+        dummyKernel.data.add(new Pair<List<Double>, String>(null, null));
         boolean readyToPredict = dummyKernel.readyToPredict();
         assertTrue(readyToPredict);
         dummyKernel.setTreshold(10L);
@@ -66,9 +67,9 @@ public void kernel_saveAndRestore_expectNormalFlow() throws IOException {
 
     }
 
-    public static ArrayList<Pair<ArrayList<Double>, String>> getTrainingData() {
-        ArrayList<Double> list = new ArrayList<>();
-        ArrayList<Pair<ArrayList<Double>, String>> data = new ArrayList<>();
+    public static List<Pair<List<Double>, String>> getTrainingData() {
+        List<Double> list = new ArrayList<>();
+        List<Pair<List<Double>, String>> data = new ArrayList<>();
 
 
         list.add((5 * 60 + 00.0) / (24 * 60));
diff --git a/src/test/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernelTest.java b/src/test/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernelTest.java
index 0a77410..1a6fdf4 100644
--- a/src/test/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernelTest.java
+++ b/src/test/java/de/dmi3y/behaiv/kernel/LogisticRegressionKernelTest.java
@@ -10,6 +10,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 import java.util.Random;
 
 import static de.dmi3y.behaiv.kernel.KernelTest.HOME;
@@ -34,7 +35,7 @@ public void setUp() throws Exception {
 
     @Test
     public void predictOne() {
-        ArrayList<Pair<ArrayList<Double>, String>> data = KernelTest.getTrainingData();
+        List<Pair<List<Double>, String>> data = KernelTest.getTrainingData();
         Kernel testKernel = new LogisticRegressionKernel("testId");
         testKernel.fit(data);
         ArrayList<Double> predictList = new ArrayList<>();
@@ -58,7 +59,7 @@ public void predictOne() {
 
     @Test
     public void storeResults() throws IOException, ClassNotFoundException {
-        ArrayList<Pair<ArrayList<Double>, String>> data = KernelTest.getTrainingData();
+        List<Pair<List<Double>, String>> data = KernelTest.getTrainingData();
         Kernel kernel = new LogisticRegressionKernel("testId");
         kernel.setId("storeTest");
         kernel.fit(data);
@@ -84,7 +85,7 @@ public void storeResults() throws IOException, ClassNotFoundException {
 
     @Test
     public void storeResults_addAdditionalLabel_shouldFail() throws IOException, ClassNotFoundException {
-        ArrayList<Pair<ArrayList<Double>, String>> data = KernelTest.getTrainingData();
+        List<Pair<List<Double>, String>> data = KernelTest.getTrainingData();
         Kernel kernel = new LogisticRegressionKernel("testId");
         kernel.setAlwaysKeepData(false);
         kernel.setId("storeTest");
@@ -142,7 +143,7 @@ public void storeResults_saveWhenDataIsNull_expectException() throws IOException
 
     @Test
     public void storeResults_saveDataAndThenTheta_expectNormalFlow() throws IOException, ClassNotFoundException {
-        ArrayList<Pair<ArrayList<Double>, String>> data = KernelTest.getTrainingData();
+        List<Pair<List<Double>, String>> data = KernelTest.getTrainingData();
         LogisticRegressionKernel kernel = new LogisticRegressionKernel("storeTest", new Random());
         kernel.data = data;
         kernel.labels = Arrays.asList("time", "lat", "lon", "headphones");
diff --git a/src/test/java/de/dmi3y/behaiv/tools/DataMappingUtilsTest.java b/src/test/java/de/dmi3y/behaiv/tools/DataMappingUtilsTest.java
index adf4ab3..09e218e 100644
--- a/src/test/java/de/dmi3y/behaiv/tools/DataMappingUtilsTest.java
+++ b/src/test/java/de/dmi3y/behaiv/tools/DataMappingUtilsTest.java
@@ -15,7 +15,7 @@ public class DataMappingUtilsTest {
 
     @Test
     public void toDistinctListOfPairValues_withInputData_returnsExpectedDistinctListOfPairValues() {
-        List<Pair<ArrayList<Double>, String>> mockData = Arrays.asList(
+        List<Pair<List<Double>, String>> mockData = Arrays.asList(
                 getMockPairListDoubleStringData(), getMockPairListDoubleStringData()
         );
         List<String> actual = DataMappingUtils.toDistinctListOfPairValues(mockData);
@@ -25,7 +25,7 @@ public void toDistinctListOfPairValues_withInputData_returnsExpectedDistinctList
 
     @Test
     public void toDistinctListOfPairValues_withEmptyListOfInputData_returnsEmptyList() {
-        List<String> actual = DataMappingUtils.toDistinctListOfPairValues(Collections.<Pair<ArrayList<Double>, String>>emptyList());
+        List<String> actual = DataMappingUtils.toDistinctListOfPairValues(Collections.<Pair<List<Double>, String>>emptyList());
         assertThat(actual, notNullValue());
         assertTrue(actual.isEmpty());
     }
@@ -67,7 +67,7 @@ public void toInput2dArray_withInputData_returnsExpected2dArray() {
 
     @Test
     public void toInput2dArray_withEmptyListOfInputData_returnsEmpty2dArray() {
-        double[][] actual = DataMappingUtils.toInput2dArray(Collections.<Pair<ArrayList<Double>, String>>emptyList());
+        double[][] actual = DataMappingUtils.toInput2dArray(Collections.<Pair<List<Double>, String>>emptyList());
         assertThat(actual.length, is(0));
     }
 
@@ -81,8 +81,8 @@ private Pair<Double, String> getMockPairDoubleStringData() {
         return new Pair<>(20d, "Fish");
     }
 
-    private Pair<ArrayList<Double>, String> getMockPairListDoubleStringData() {
-        ArrayList<Double> myDoubleList = new ArrayList<>();
+    private Pair<List<Double>, String> getMockPairListDoubleStringData() {
+        List<Double> myDoubleList = new ArrayList<>();
         myDoubleList.add(20d);
         return new Pair<>(myDoubleList, "Potato");
     }