Suggested small changes to Java code for slightly more standard style, encapsulation and in some cases performance

14 files changed, 164 insertions, 83 deletions

diff --git a/examples/src/main/java/org/apache/spark/examples/JavaHdfsLR.java b/examples/src/main/java/org/apache/spark/examples/JavaHdfsLR.java
index be0d38589c..9f0e3412a6 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaHdfsLR.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaHdfsLR.java
@@ -24,19 +24,22 @@ import org.apache.spark.api.java.function.Function2;
 
 import java.io.Serializable;
 import java.util.Arrays;
-import java.util.StringTokenizer;
 import java.util.Random;
+import java.util.regex.Pattern;
 
 /**
  * Logistic regression based classification.
  */
-public class JavaHdfsLR {
+public final class JavaHdfsLR {
 
-  static int D = 10;   // Number of dimensions
-  static Random rand = new Random(42);
+  private static final int D = 10;   // Number of dimensions
+  private static final Random rand = new Random(42);
+
+  private JavaHdfsLR() {
+  }
 
   static class DataPoint implements Serializable {
-    public DataPoint(double[] x, double y) {
+    DataPoint(double[] x, double y) {
       this.x = x;
       this.y = y;
     }
@@ -46,20 +49,22 @@ public class JavaHdfsLR {
   }
 
   static class ParsePoint extends Function<String, DataPoint> {
+    private static final Pattern SPACE = Pattern.compile(" ");
+
+    @Override
     public DataPoint call(String line) {
-      StringTokenizer tok = new StringTokenizer(line, " ");
-      double y = Double.parseDouble(tok.nextToken());
+      String[] tok = SPACE.split(line);
+      double y = Double.parseDouble(tok[0]);
       double[] x = new double[D];
-      int i = 0;
-      while (i < D) {
-        x[i] = Double.parseDouble(tok.nextToken());
-        i += 1;
+      for (int i = 0; i < D; i++) {
+        x[i] = Double.parseDouble(tok[i+1]);
       }
       return new DataPoint(x, y);
     }
   }
 
   static class VectorSum extends Function2<double[], double[], double[]> {
+    @Override
     public double[] call(double[] a, double[] b) {
       double[] result = new double[D];
       for (int j = 0; j < D; j++) {
@@ -70,12 +75,13 @@ public class JavaHdfsLR {
   }
 
   static class ComputeGradient extends Function<DataPoint, double[]> {
-    double[] weights;
+    private final double[] weights;
 
-    public ComputeGradient(double[] weights) {
+    ComputeGradient(double[] weights) {
       this.weights = weights;
     }
 
+    @Override
     public double[] call(DataPoint p) {
       double[] gradient = new double[D];
       for (int i = 0; i < D; i++) {
diff --git a/examples/src/main/java/org/apache/spark/examples/JavaKMeans.java b/examples/src/main/java/org/apache/spark/examples/JavaKMeans.java
index 5a6afe7eae..1671d0cdc8 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaKMeans.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaKMeans.java
@@ -27,19 +27,27 @@ import org.apache.spark.util.Vector;
 
 import java.util.List;
 import java.util.Map;
+import java.util.regex.Pattern;
 
 /**
  * K-means clustering using Java API.
  */
-public class JavaKMeans {
+public final class JavaKMeans {
+
+  private static final Pattern SPACE = Pattern.compile(" ");
+
+  private JavaKMeans() {
+  }
 
   /** Parses numbers split by whitespace to a vector */
   static Vector parseVector(String line) {
-    String[] splits = line.split(" ");
+    String[] splits = SPACE.split(line);
     double[] data = new double[splits.length];
     int i = 0;
-    for (String s : splits)
-      data[i] = Double.parseDouble(splits[i++]);
+    for (String s : splits) {
+      data[i] = Double.parseDouble(s);
+      i++;
+    }
     return new Vector(data);
   }
 
@@ -82,7 +90,7 @@ public class JavaKMeans {
     JavaRDD<Vector> data = sc.textFile(path).map(
       new Function<String, Vector>() {
         @Override
-        public Vector call(String line) throws Exception {
+        public Vector call(String line) {
           return parseVector(line);
         }
       }
@@ -96,7 +104,7 @@ public class JavaKMeans {
       JavaPairRDD<Integer, Vector> closest = data.map(
         new PairFunction<Vector, Integer, Vector>() {
           @Override
-          public Tuple2<Integer, Vector> call(Vector vector) throws Exception {
+          public Tuple2<Integer, Vector> call(Vector vector) {
             return new Tuple2<Integer, Vector>(
               closestPoint(vector, centroids), vector);
           }
@@ -107,7 +115,8 @@ public class JavaKMeans {
       JavaPairRDD<Integer, List<Vector>> pointsGroup = closest.groupByKey();
       Map<Integer, Vector> newCentroids = pointsGroup.mapValues(
         new Function<List<Vector>, Vector>() {
-          public Vector call(List<Vector> ps) throws Exception {
+          @Override
+          public Vector call(List<Vector> ps) {
             return average(ps);
           }
         }).collectAsMap();
@@ -122,8 +131,9 @@ public class JavaKMeans {
     } while (tempDist > convergeDist);
 
     System.out.println("Final centers:");
-    for (Vector c : centroids)
+    for (Vector c : centroids) {
       System.out.println(c);
+    }
 
     System.exit(0);
 
diff --git a/examples/src/main/java/org/apache/spark/examples/JavaLogQuery.java b/examples/src/main/java/org/apache/spark/examples/JavaLogQuery.java
index 407cd7ccfa..1ce53fe403 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaLogQuery.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaLogQuery.java
@@ -35,9 +35,9 @@ import java.util.regex.Pattern;
 /**
  * Executes a roll up-style query against Apache logs.
  */
-public class JavaLogQuery {
+public final class JavaLogQuery {
 
-  public static List<String> exampleApacheLogs = Lists.newArrayList(
+  public static final List<String> exampleApacheLogs = Lists.newArrayList(
     "10.10.10.10 - \"FRED\" [18/Jan/2013:17:56:07 +1100] \"GET http://images.com/2013/Generic.jpg " +
       "HTTP/1.1\" 304 315 \"http://referall.com/\" \"Mozilla/4.0 (compatible; MSIE 7.0; " +
       "Windows NT 5.1; GTB7.4; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; " +
@@ -51,14 +51,17 @@ public class JavaLogQuery {
       "3.5.30729; Release=ARP)\" \"UD-1\" - \"image/jpeg\" \"whatever\" 0.352 \"-\" - \"\" 256 977 988 \"\" " +
       "0 73.23.2.15 images.com 1358492557 - Whatup");
 
-  public static Pattern apacheLogRegex = Pattern.compile(
+  public static final Pattern apacheLogRegex = Pattern.compile(
     "^([\\d.]+) (\\S+) (\\S+) \\[([\\w\\d:/]+\\s[+\\-]\\d{4})\\] \"(.+?)\" (\\d{3}) ([\\d\\-]+) \"([^\"]+)\" \"([^\"]+)\".*");
 
+  private JavaLogQuery() {
+  }
+
   /** Tracks the total query count and number of aggregate bytes for a particular group. */
   public static class Stats implements Serializable {
 
-    private int count;
-    private int numBytes;
+    private final int count;
+    private final int numBytes;
 
     public Stats(int count, int numBytes) {
       this.count = count;
@@ -92,12 +95,12 @@ public class JavaLogQuery {
     if (m.find()) {
       int bytes = Integer.parseInt(m.group(7));
       return new Stats(1, bytes);
-    }
-    else
+    } else {
       return new Stats(1, 0);
+    }
   }
 
-  public static void main(String[] args) throws Exception {
+  public static void main(String[] args) {
     if (args.length == 0) {
       System.err.println("Usage: JavaLogQuery <master> [logFile]");
       System.exit(1);
@@ -110,14 +113,14 @@ public class JavaLogQuery {
 
     JavaPairRDD<Tuple3<String, String, String>, Stats> extracted = dataSet.map(new PairFunction<String, Tuple3<String, String, String>, Stats>() {
       @Override
-      public Tuple2<Tuple3<String, String, String>, Stats> call(String s) throws Exception {
+      public Tuple2<Tuple3<String, String, String>, Stats> call(String s) {
         return new Tuple2<Tuple3<String, String, String>, Stats>(extractKey(s), extractStats(s));
       }
     });
 
     JavaPairRDD<Tuple3<String, String, String>, Stats> counts = extracted.reduceByKey(new Function2<Stats, Stats, Stats>() {
       @Override
-      public Stats call(Stats stats, Stats stats2) throws Exception {
+      public Stats call(Stats stats, Stats stats2) {
         return stats.merge(stats2);
       }
     });
diff --git a/examples/src/main/java/org/apache/spark/examples/JavaPageRank.java b/examples/src/main/java/org/apache/spark/examples/JavaPageRank.java
index 89aed8f279..447ba93bd6 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaPageRank.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaPageRank.java
@@ -28,6 +28,7 @@ import org.apache.spark.api.java.function.PairFunction;
 
 import java.util.List;
 import java.util.ArrayList;
+import java.util.regex.Pattern;
 
 /**
  * Computes the PageRank of URLs from an input file. Input file should
@@ -38,7 +39,12 @@ import java.util.ArrayList;
  * ...
  * where URL and their neighbors are separated by space(s).
  */
-public class JavaPageRank {
+public final class JavaPageRank {
+  private static final Pattern SPACES = Pattern.compile("\\s+");
+
+  private JavaPageRank() {
+  }
+
   private static class Sum extends Function2<Double, Double, Double> {
     @Override
     public Double call(Double a, Double b) {
@@ -66,7 +72,7 @@ public class JavaPageRank {
     JavaPairRDD<String, List<String>> links = lines.map(new PairFunction<String, String, String>() {
       @Override
       public Tuple2<String, String> call(String s) {
-        String[] parts = s.split("\\s+");
+        String[] parts = SPACES.split(s);
         return new Tuple2<String, String>(parts[0], parts[1]);
       }
     }).distinct().groupByKey().cache();
@@ -74,7 +80,7 @@ public class JavaPageRank {
     // Loads all URLs with other URL(s) link to from input file and initialize ranks of them to one.
     JavaPairRDD<String, Double> ranks = links.mapValues(new Function<List<String>, Double>() {
       @Override
-      public Double call(List<String> rs) throws Exception {
+      public Double call(List<String> rs) {
         return 1.0;
       }
     });
@@ -97,7 +103,7 @@ public class JavaPageRank {
       // Re-calculates URL ranks based on neighbor contributions.
       ranks = contribs.reduceByKey(new Sum()).mapValues(new Function<Double, Double>() {
         @Override
-        public Double call(Double sum) throws Exception {
+        public Double call(Double sum) {
           return 0.15 + sum * 0.85;
         }
       });
diff --git a/examples/src/main/java/org/apache/spark/examples/JavaSparkPi.java b/examples/src/main/java/org/apache/spark/examples/JavaSparkPi.java
index 4a2380caf5..d2a2a1db7c 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaSparkPi.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaSparkPi.java
@@ -26,8 +26,10 @@ import java.util.ArrayList;
 import java.util.List;
 
 /** Computes an approximation to pi */
-public class JavaSparkPi {
+public final class JavaSparkPi {
 
+  private JavaSparkPi() {
+  }
 
   public static void main(String[] args) throws Exception {
     if (args.length == 0) {
@@ -41,21 +43,22 @@ public class JavaSparkPi {
     int slices = (args.length == 2) ? Integer.parseInt(args[1]) : 2;
     int n = 100000 * slices;
     List<Integer> l = new ArrayList<Integer>(n);
-    for (int i = 0; i < n; i++)
+    for (int i = 0; i < n; i++) {
       l.add(i);
+    }
 
     JavaRDD<Integer> dataSet = jsc.parallelize(l, slices);
 
     int count = dataSet.map(new Function<Integer, Integer>() {
       @Override
-      public Integer call(Integer integer) throws Exception {
+      public Integer call(Integer integer) {
         double x = Math.random() * 2 - 1;
         double y = Math.random() * 2 - 1;
         return (x * x + y * y < 1) ? 1 : 0;
       }
     }).reduce(new Function2<Integer, Integer, Integer>() {
       @Override
-      public Integer call(Integer integer, Integer integer2) throws Exception {
+      public Integer call(Integer integer, Integer integer2) {
         return integer + integer2;
       }
     });
diff --git a/examples/src/main/java/org/apache/spark/examples/JavaTC.java b/examples/src/main/java/org/apache/spark/examples/JavaTC.java
index 17f21f6b77..e61b9c4f0e 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaTC.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaTC.java
@@ -31,11 +31,14 @@ import java.util.Set;
 /**
  * Transitive closure on a graph, implemented in Java.
  */
-public class JavaTC {
+public final class JavaTC {
 
-  static int numEdges = 200;
-  static int numVertices = 100;
-  static Random rand = new Random(42);
+  private static final int numEdges = 200;
+  private static final int numVertices = 100;
+  private static final Random rand = new Random(42);
+
+  private JavaTC() {
+  }
 
   static List<Tuple2<Integer, Integer>> generateGraph() {
     Set<Tuple2<Integer, Integer>> edges = new HashSet<Tuple2<Integer, Integer>>(numEdges);
@@ -43,15 +46,18 @@ public class JavaTC {
       int from = rand.nextInt(numVertices);
       int to = rand.nextInt(numVertices);
       Tuple2<Integer, Integer> e = new Tuple2<Integer, Integer>(from, to);
-      if (from != to) edges.add(e);
+      if (from != to) {
+        edges.add(e);
+      }
     }
     return new ArrayList<Tuple2<Integer, Integer>>(edges);
   }
 
   static class ProjectFn extends PairFunction<Tuple2<Integer, Tuple2<Integer, Integer>>,
       Integer, Integer> {
-    static ProjectFn INSTANCE = new ProjectFn();
+    static final ProjectFn INSTANCE = new ProjectFn();
 
+    @Override
     public Tuple2<Integer, Integer> call(Tuple2<Integer, Tuple2<Integer, Integer>> triple) {
       return new Tuple2<Integer, Integer>(triple._2()._2(), triple._2()._1());
     }
@@ -76,6 +82,7 @@ public class JavaTC {
     // Because join() joins on keys, the edges are stored in reversed order.
     JavaPairRDD<Integer, Integer> edges = tc.map(
       new PairFunction<Tuple2<Integer, Integer>, Integer, Integer>() {
+        @Override
         public Tuple2<Integer, Integer> call(Tuple2<Integer, Integer> e) {
           return new Tuple2<Integer, Integer>(e._2(), e._1());
         }
diff --git a/examples/src/main/java/org/apache/spark/examples/JavaWordCount.java b/examples/src/main/java/org/apache/spark/examples/JavaWordCount.java
index bd6383e13d..ed4e9b49d0 100644
--- a/examples/src/main/java/org/apache/spark/examples/JavaWordCount.java
+++ b/examples/src/main/java/org/apache/spark/examples/JavaWordCount.java
@@ -27,8 +27,14 @@ import org.apache.spark.api.java.function.PairFunction;
 
 import java.util.Arrays;
 import java.util.List;
+import java.util.regex.Pattern;
+
+public final class JavaWordCount {
+  private static final Pattern SPACE = Pattern.compile(" ");
+
+  private JavaWordCount() {
+  }
 
-public class JavaWordCount {
   public static void main(String[] args) throws Exception {
     if (args.length < 2) {
       System.err.println("Usage: JavaWordCount <master> <file>");
@@ -40,18 +46,21 @@ public class JavaWordCount {
     JavaRDD<String> lines = ctx.textFile(args[1], 1);
 
     JavaRDD<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
+      @Override
       public Iterable<String> call(String s) {
-        return Arrays.asList(s.split(" "));
+        return Arrays.asList(SPACE.split(s));
       }
     });
     
     JavaPairRDD<String, Integer> ones = words.map(new PairFunction<String, String, Integer>() {
+      @Override
       public Tuple2<String, Integer> call(String s) {
         return new Tuple2<String, Integer>(s, 1);
       }
     });
     
     JavaPairRDD<String, Integer> counts = ones.reduceByKey(new Function2<Integer, Integer, Integer>() {
+      @Override
       public Integer call(Integer i1, Integer i2) {
         return i1 + i2;
       }
diff --git a/examples/src/main/java/org/apache/spark/mllib/examples/JavaALS.java b/examples/src/main/java/org/apache/spark/mllib/examples/JavaALS.java
index 45a0d237da..b33e648147 100644
--- a/examples/src/main/java/org/apache/spark/mllib/examples/JavaALS.java
+++ b/examples/src/main/java/org/apache/spark/mllib/examples/JavaALS.java
@@ -26,28 +26,35 @@ import org.apache.spark.mllib.recommendation.MatrixFactorizationModel;
 import org.apache.spark.mllib.recommendation.Rating;
 
 import java.util.Arrays;
-import java.util.StringTokenizer;
+import java.util.regex.Pattern;
 
 import scala.Tuple2;
 
 /**
  * Example using MLLib ALS from Java.
  */
-public class  JavaALS {
+public final class  JavaALS {
+
+  private JavaALS() {
+  }
 
   static class ParseRating extends Function<String, Rating> {
+    private static final Pattern COMMA = Pattern.compile(",");
+
+    @Override
     public Rating call(String line) {
-      StringTokenizer tok = new StringTokenizer(line, ",");
-      int x = Integer.parseInt(tok.nextToken());
-      int y = Integer.parseInt(tok.nextToken());
-      double rating = Double.parseDouble(tok.nextToken());
+      String[] tok = COMMA.split(line);
+      int x = Integer.parseInt(tok[0]);
+      int y = Integer.parseInt(tok[1]);
+      double rating = Double.parseDouble(tok[2]);
       return new Rating(x, y, rating);
     }
   }
 
   static class FeaturesToString extends Function<Tuple2<Object, double[]>, String> {
+    @Override
     public String call(Tuple2<Object, double[]> element) {
-      return element._1().toString() + "," + Arrays.toString(element._2());
+      return element._1() + "," + Arrays.toString(element._2());
     }
   }
 
diff --git a/examples/src/main/java/org/apache/spark/mllib/examples/JavaKMeans.java b/examples/src/main/java/org/apache/spark/mllib/examples/JavaKMeans.java
index cd59a139b9..a9db04d525 100644
--- a/examples/src/main/java/org/apache/spark/mllib/examples/JavaKMeans.java
+++ b/examples/src/main/java/org/apache/spark/mllib/examples/JavaKMeans.java
@@ -25,20 +25,25 @@ import org.apache.spark.mllib.clustering.KMeans;
 import org.apache.spark.mllib.clustering.KMeansModel;
 
 import java.util.Arrays;
-import java.util.StringTokenizer;
+import java.util.regex.Pattern;
 
 /**
  * Example using MLLib KMeans from Java.
  */
-public class JavaKMeans {
+public final class JavaKMeans {
+
+  private JavaKMeans() {
+  }
 
   static class ParsePoint extends Function<String, double[]> {
+    private static final Pattern SPACE = Pattern.compile(" ");
+
+    @Override
     public double[] call(String line) {
-      StringTokenizer tok = new StringTokenizer(line, " ");
-      int numTokens = tok.countTokens();
-      double[] point = new double[numTokens];
-      for (int i = 0; i < numTokens; ++i) {
-        point[i] = Double.parseDouble(tok.nextToken());
+      String[] tok = SPACE.split(line);
+      double[] point = new double[tok.length];
+      for (int i = 0; i < tok.length; ++i) {
+        point[i] = Double.parseDouble(tok[i]);
       }
       return point;
     }
diff --git a/examples/src/main/java/org/apache/spark/mllib/examples/JavaLR.java b/examples/src/main/java/org/apache/spark/mllib/examples/JavaLR.java
index 258061c8e6..56341315bf 100644
--- a/examples/src/main/java/org/apache/spark/mllib/examples/JavaLR.java
+++ b/examples/src/main/java/org/apache/spark/mllib/examples/JavaLR.java
@@ -27,22 +27,28 @@ import org.apache.spark.mllib.classification.LogisticRegressionModel;
 import org.apache.spark.mllib.regression.LabeledPoint;
 
 import java.util.Arrays;
-import java.util.StringTokenizer;
+import java.util.regex.Pattern;
 
 /**
  * Logistic regression based classification using ML Lib.
  */
-public class JavaLR {
+public final class JavaLR {
+
+  private JavaLR() {
+  }
 
   static class ParsePoint extends Function<String, LabeledPoint> {
+    private static final Pattern COMMA = Pattern.compile(",");
+    private static final Pattern SPACE = Pattern.compile(" ");
+
+    @Override
     public LabeledPoint call(String line) {
-      String[] parts = line.split(",");
+      String[] parts = COMMA.split(line);
       double y = Double.parseDouble(parts[0]);
-      StringTokenizer tok = new StringTokenizer(parts[1], " ");
-      int numTokens = tok.countTokens();
-      double[] x = new double[numTokens];
-      for (int i = 0; i < numTokens; ++i) {
-        x[i] = Double.parseDouble(tok.nextToken());
+      String[] tok = SPACE.split(parts[1]);
+      double[] x = new double[tok.length];
+      for (int i = 0; i < tok.length; ++i) {
+        x[i] = Double.parseDouble(tok[i]);
       }
       return new LabeledPoint(y, x);
     }
diff --git a/examples/src/main/java/org/apache/spark/streaming/examples/JavaFlumeEventCount.java b/examples/src/main/java/org/apache/spark/streaming/examples/JavaFlumeEventCount.java
index 261813bf2f..bd0bbb56ff 100644
--- a/examples/src/main/java/org/apache/spark/streaming/examples/JavaFlumeEventCount.java
+++ b/examples/src/main/java/org/apache/spark/streaming/examples/JavaFlumeEventCount.java
@@ -36,7 +36,10 @@ import org.apache.spark.streaming.dstream.SparkFlumeEvent;
  *           creates a server and listens for flume events.
  *    <port> is the port the Flume receiver will listen on.
  */
-public class JavaFlumeEventCount {
+public final class JavaFlumeEventCount {
+  private JavaFlumeEventCount() {
+  }
+
   public static void main(String[] args) {
     if (args.length != 3) {
       System.err.println("Usage: JavaFlumeEventCount <master> <host> <port>");
diff --git a/examples/src/main/java/org/apache/spark/streaming/examples/JavaKafkaWordCount.java b/examples/src/main/java/org/apache/spark/streaming/examples/JavaKafkaWordCount.java
index 22994fb2ec..17eb871908 100644
--- a/examples/src/main/java/org/apache/spark/streaming/examples/JavaKafkaWordCount.java
+++ b/examples/src/main/java/org/apache/spark/streaming/examples/JavaKafkaWordCount.java
@@ -19,6 +19,7 @@ package org.apache.spark.streaming.examples;
 
 import java.util.Map;
 import java.util.HashMap;
+import java.util.regex.Pattern;
 
 import com.google.common.collect.Lists;
 import org.apache.spark.api.java.function.FlatMapFunction;
@@ -45,7 +46,12 @@ import scala.Tuple2;
  *    zoo03 my-consumer-group topic1,topic2 1`
  */
 
-public class JavaKafkaWordCount {
+public final class JavaKafkaWordCount {
+  private static final Pattern SPACE = Pattern.compile(" ");
+
+  private JavaKafkaWordCount() {
+  }
+
   public static void main(String[] args) {
     if (args.length < 5) {
       System.err.println("Usage: KafkaWordCount <master> <zkQuorum> <group> <topics> <numThreads>");
@@ -67,7 +73,7 @@ public class JavaKafkaWordCount {
 
     JavaDStream<String> lines = messages.map(new Function<Tuple2<String, String>, String>() {
       @Override
-      public String call(Tuple2<String, String> tuple2) throws Exception {
+      public String call(Tuple2<String, String> tuple2) {
         return tuple2._2();
       }
     });
@@ -75,19 +81,19 @@ public class JavaKafkaWordCount {
     JavaDStream<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
       @Override
       public Iterable<String> call(String x) {
-        return Lists.newArrayList(x.split(" "));
+        return Lists.newArrayList(SPACE.split(x));
       }
     });
 
     JavaPairDStream<String, Integer> wordCounts = words.map(
       new PairFunction<String, String, Integer>() {
         @Override
-        public Tuple2<String, Integer> call(String s) throws Exception {
+        public Tuple2<String, Integer> call(String s) {
           return new Tuple2<String, Integer>(s, 1);
         }
       }).reduceByKey(new Function2<Integer, Integer, Integer>() {
         @Override
-        public Integer call(Integer i1, Integer i2) throws Exception {
+        public Integer call(Integer i1, Integer i2) {
           return i1 + i2;
         }
       });
diff --git a/examples/src/main/java/org/apache/spark/streaming/examples/JavaNetworkWordCount.java b/examples/src/main/java/org/apache/spark/streaming/examples/JavaNetworkWordCount.java
index def87c199b..fb090cc262 100644
--- a/examples/src/main/java/org/apache/spark/streaming/examples/JavaNetworkWordCount.java
+++ b/examples/src/main/java/org/apache/spark/streaming/examples/JavaNetworkWordCount.java
@@ -27,6 +27,8 @@ import org.apache.spark.streaming.api.java.JavaDStream;
 import org.apache.spark.streaming.api.java.JavaPairDStream;
 import org.apache.spark.streaming.api.java.JavaStreamingContext;
 
+import java.util.regex.Pattern;
+
 /**
  * Counts words in UTF8 encoded, '\n' delimited text received from the network every second.
  * Usage: NetworkWordCount <master> <hostname> <port>
@@ -38,7 +40,12 @@ import org.apache.spark.streaming.api.java.JavaStreamingContext;
  * and then run the example
  *    `$ ./run spark.streaming.examples.JavaNetworkWordCount local[2] localhost 9999`
  */
-public class JavaNetworkWordCount {
+public final class JavaNetworkWordCount {
+  private static final Pattern SPACE = Pattern.compile(" ");
+
+  private JavaNetworkWordCount() {
+  }
+
   public static void main(String[] args) {
     if (args.length < 3) {
       System.err.println("Usage: NetworkWordCount <master> <hostname> <port>\n" +
@@ -56,18 +63,18 @@ public class JavaNetworkWordCount {
     JavaDStream<String> words = lines.flatMap(new FlatMapFunction<String, String>() {
       @Override
       public Iterable<String> call(String x) {
-        return Lists.newArrayList(x.split(" "));
+        return Lists.newArrayList(SPACE.split(x));
       }
     });
     JavaPairDStream<String, Integer> wordCounts = words.map(
       new PairFunction<String, String, Integer>() {
         @Override
-        public Tuple2<String, Integer> call(String s) throws Exception {
+        public Tuple2<String, Integer> call(String s) {
           return new Tuple2<String, Integer>(s, 1);
         }
       }).reduceByKey(new Function2<Integer, Integer, Integer>() {
         @Override
-        public Integer call(Integer i1, Integer i2) throws Exception {
+        public Integer call(Integer i1, Integer i2) {
           return i1 + i2;
         }
       });
diff --git a/examples/src/main/java/org/apache/spark/streaming/examples/JavaQueueStream.java b/examples/src/main/java/org/apache/spark/streaming/examples/JavaQueueStream.java
index c8c7389dd1..6be967237c 100644
--- a/examples/src/main/java/org/apache/spark/streaming/examples/JavaQueueStream.java
+++ b/examples/src/main/java/org/apache/spark/streaming/examples/JavaQueueStream.java
@@ -31,8 +31,11 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Queue;
 
-public class JavaQueueStream {
-  public static void main(String[] args) throws InterruptedException {
+public final class JavaQueueStream {
+  private JavaQueueStream() {
+  }
+
+  public static void main(String[] args) throws Exception {
     if (args.length < 1) {
       System.err.println("Usage: JavaQueueStream <master>");
       System.exit(1);
@@ -62,14 +65,14 @@ public class JavaQueueStream {
     JavaPairDStream<Integer, Integer> mappedStream = inputStream.map(
         new PairFunction<Integer, Integer, Integer>() {
           @Override
-          public Tuple2<Integer, Integer> call(Integer i) throws Exception {
+          public Tuple2<Integer, Integer> call(Integer i) {
             return new Tuple2<Integer, Integer>(i % 10, 1);
           }
         });
     JavaPairDStream<Integer, Integer> reducedStream = mappedStream.reduceByKey(
       new Function2<Integer, Integer, Integer>() {
         @Override
-        public Integer call(Integer i1, Integer i2) throws Exception {
+        public Integer call(Integer i1, Integer i2) {
           return i1 + i2;
         }
     });