HADOOP-11372. Fix new findbugs warnings in mapreduce-examples. Contributed by Li Lu.

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -542,6 +542,9 @@ Release 2.7.0 - UNRELEASED
     HADOOP-11368. Fix SSLFactory truststore reloader thread leak in
     KMSClientProvider. (Arun Suresh via wang)
 
+    HADOOP-11372. Fix new findbugs warnings in mapreduce-examples.
+    (Li Lu via wheat9)
+
 Release 2.6.0 - 2014-11-18
 
   INCOMPATIBLE CHANGES

hadoop-mapreduce-project/hadoop-mapreduce-examples/src/main/java/org/apache/hadoop/examples/pi/Parser.java

@@ -151,11 +151,10 @@ public final class Parser {
   static <T extends Combinable<T>> Map<Parameter, T> combine(Map<Parameter, List<T>> m) {
     final Map<Parameter, T> combined = new TreeMap<Parameter, T>();
     for(Parameter p : Parameter.values()) {
+      //note: results would never be null due to the design of Util.combine
       final List<T> results = Util.combine(m.get(p));
       Util.out.format("%-6s => ", p); 
-      if (results == null)
-        Util.out.println("null");
-      else if (results.size() != 1) 
+      if (results.size() != 1)
         Util.out.println(results.toString().replace(", ", ",\n           "));
       else {
         final T r = results.get(0);

hadoop-mapreduce-project/hadoop-mapreduce-examples/src/main/java/org/apache/hadoop/examples/pi/math/Bellard.java

@@ -25,6 +25,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
+import java.util.NoSuchElementException;
 
 import org.apache.hadoop.examples.pi.Container;
 import org.apache.hadoop.examples.pi.Util;
@@ -255,7 +256,13 @@ public final class Bellard {
         public boolean hasNext() {return i < parts.length;}
         /** {@inheritDoc} */
         @Override
-        public Summation next() {return parts[i++];}
+        public Summation next() throws NoSuchElementException {
+          if (hasNext()) {
+            return parts[i++];
+          } else {
+            throw new NoSuchElementException("Sum's iterator does not have next!");
+          }
+        }
         /** Unsupported */
         @Override
         public void remove() {throw new UnsupportedOperationException();}