diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Capacity.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Capacity.java
index 0017d21a..094398f0 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Capacity.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Capacity.java
@@ -171,9 +171,7 @@ public class Capacity {
         }
 
         private void copy(int[] from, int[] to) {
-            for (int i = 0; i < dimensions.length; i++) {
-                to[i] = from[i];
-            }
+            System.arraycopy(from, 0, to, 0, dimensions.length);
         }
 
         /**
@@ -195,7 +193,7 @@ public class Capacity {
      *
      * @param capacity capacity to be copied
      */
-    Capacity(Capacity capacity) {
+    private Capacity(Capacity capacity) {
         this.dimensions = new int[capacity.getNuOfDimensions()];
         for (int i = 0; i < capacity.getNuOfDimensions(); i++) {
             this.dimensions[i] = capacity.get(i);
@@ -261,11 +259,11 @@ public class Capacity {
 
     @Override
     public String toString() {
-        String string = "[noDimensions=" + getNuOfDimensions() + "]";
+        StringBuilder string = new StringBuilder("[noDimensions=" + getNuOfDimensions() + "]");
         for (int i = 0; i < getNuOfDimensions(); i++) {
-            string += "[[dimIndex=" + i + "][dimValue=" + dimensions[i] + "]]";
+            string.append("[[dimIndex=").append(i).append("][dimValue=").append(dimensions[i]).append("]]");
         }
-        return string;
+        return string.toString();
     }
 
     /**
@@ -300,9 +298,7 @@ public class Capacity {
 
         Capacity capacity = (Capacity) o;
 
-        if (!Arrays.equals(dimensions, capacity.dimensions)) return false;
-
-        return true;
+        return Arrays.equals(dimensions, capacity.dimensions);
     }
 
     @Override
diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasId.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasId.java
index 8c4b6351..74e7f842 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasId.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasId.java
@@ -23,6 +23,6 @@ package com.graphhopper.jsprit.core.problem;
  */
 public interface HasId {
 
-    public String getId();
+    String getId();
 
 }
diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasIndex.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasIndex.java
index f8830cb8..edbfc922 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasIndex.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/HasIndex.java
@@ -23,6 +23,6 @@ package com.graphhopper.jsprit.core.problem;
  */
 public interface HasIndex {
 
-    public int getIndex();
+    int getIndex();
 
 }
diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/JobActivityFactory.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/JobActivityFactory.java
index 8ee69533..3911f6b7 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/JobActivityFactory.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/JobActivityFactory.java
@@ -27,6 +27,6 @@ import java.util.List;
  */
 public interface JobActivityFactory {
 
-    public List<AbstractActivity> createActivities(Job job);
+    List<AbstractActivity> createActivities(Job job);
 
 }
diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Location.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Location.java
index 51c74612..d15bf4e4 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Location.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Location.java
@@ -49,8 +49,8 @@ public final class Location implements HasIndex, HasId {
     /**
      * Factory method (and shortcut) for creating location object just with location index
      *
-     * @param index
-     * @return
+     * @param index of location
+     * @return this builder
      */
     public static Location newInstance(int index) {
         return Location.Builder.newInstance().setIndex(index).build();
@@ -92,7 +92,7 @@ public final class Location implements HasIndex, HasId {
         /**
          * Sets location index
          *
-         * @param index
+         * @param index location index
          * @return the builder
          */
         public Builder setIndex(int index) {
@@ -104,8 +104,8 @@ public final class Location implements HasIndex, HasId {
         /**
          * Sets coordinate of location
          *
-         * @param coordinate
-         * @return
+         * @param coordinate of location
+         * @return this Builder
          */
         public Builder setCoordinate(Coordinate coordinate) {
             this.coordinate = coordinate;
@@ -115,8 +115,8 @@ public final class Location implements HasIndex, HasId {
         /**
          * Sets location id
          *
-         * @param id
-         * @return
+         * @param id id of location
+         * @return this Builder
          */
         public Builder setId(String id) {
             this.id = id;
@@ -126,8 +126,8 @@ public final class Location implements HasIndex, HasId {
         /**
          * Adds name, e.g. street name, to location
          *
-         * @param name
-         * @return
+         * @param name name of location
+         * @return this Builder
          */
         public Builder setName(String name) {
             this.name = name;
@@ -198,14 +198,10 @@ public final class Location implements HasIndex, HasId {
     public boolean equals(Object o) {
         if (this == o) return true;
         if (!(o instanceof Location)) return false;
-
         Location location = (Location) o;
-
         if (index != location.index) return false;
         if (coordinate != null ? !coordinate.equals(location.coordinate) : location.coordinate != null) return false;
-        if (id != null ? !id.equals(location.id) : location.id != null) return false;
-
-        return true;
+        return id != null ? id.equals(location.id) : location.id == null;
     }
 
     @Override
diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Skills.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Skills.java
index ddc7df8e..f52831fc 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Skills.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/Skills.java
@@ -39,7 +39,7 @@ public class Skills {
             return new Builder();
         }
 
-        private Set<String> skills = new HashSet<String>();
+        private Set<String> skills = new HashSet<>();
 
         /**
          * Adds skill. Skill is transformed into lowerCase.
@@ -74,7 +74,7 @@ public class Skills {
 
     }
 
-    private Set<String> skills = new HashSet<String>();
+    private Set<String> skills = new HashSet<>();
 
     private Skills(Builder builder) {
         skills.addAll(builder.skills);
@@ -90,16 +90,16 @@ public class Skills {
     }
 
     public String toString() {
-        String s = "[";
+        StringBuilder s = new StringBuilder("[");
         boolean first = true;
         for (String skill : values()) {
             if (first) {
-                s += skill;
+                s.append(skill);
                 first = false;
-            } else s += ", " + skill;
+            } else s.append(", ").append(skill);
         }
-        s += "]";
-        return s;
+        s.append("]");
+        return s.toString();
     }
 
     /**
@@ -119,9 +119,7 @@ public class Skills {
 
         Skills skills1 = (Skills) o;
 
-        if (skills != null ? !skills.equals(skills1.skills) : skills1.skills != null) return false;
-
-        return true;
+        return skills != null ? skills.equals(skills1.skills) : skills1.skills == null;
     }
 
     @Override
diff --git a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/VehicleRoutingProblem.java b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/VehicleRoutingProblem.java
index fa6afae5..328d9a46 100644
--- a/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/VehicleRoutingProblem.java
+++ b/jsprit-core/src/main/java/com/graphhopper/jsprit/core/problem/VehicleRoutingProblem.java
@@ -157,14 +157,7 @@ public class VehicleRoutingProblem {
          * @return locations
          */
         public Locations getLocations() {
-            return new Locations() {
-
-                @Override
-                public Coordinate getCoord(String id) {
-                    return tentative_coordinates.get(id);
-                }
-
-            };
+            return id -> tentative_coordinates.get(id);
         }
 
         /**
@@ -513,7 +506,6 @@ public class VehicleRoutingProblem {
         }
 
         private Builder addService(Service service) {
-//            tentative_coordinates.put(service.getLocation().getId(), service.getLocation().getCoordinate());
             addLocationToTentativeLocations(service);
             if (jobs.containsKey(service.getId())) {
                 logger.warn("The service " + service + " has already been added to job list. This overrides existing job.");
@@ -579,14 +571,7 @@ public class VehicleRoutingProblem {
 
     private int nuActivities;
 
-    private final JobActivityFactory jobActivityFactory = new JobActivityFactory() {
-
-        @Override
-        public List<AbstractActivity> createActivities(Job job) {
-            return copyAndGetActivities(job);
-        }
-
-    };
+    private final JobActivityFactory jobActivityFactory = job -> copyAndGetActivities(job);
 
     private VehicleRoutingProblem(Builder builder) {
         this.jobs = builder.jobs;