Changes between Initial Version and Version 1 of waue/2010/0119

Timestamp:

Jan 19, 2010, 11:21:17 AM (15 years ago)

Author:

waue

Comment:

--

waue/2010/0119

@@ +1 @@
+= Debug =
+{{{
+#!java
+public class HelloHadoop {
+
+        public class HelloMapper extends
+                        Mapper<LongWritable, Text, LongWritable, Text> {
+....
+        }
+
+         public class HelloReducer extends
+                        Reducer<LongWritable, Text, LongWritable, Text> {
+...
+                }
+        }
+
+        public static void main(String[] args) throws IOException,
+                        InterruptedException, ClassNotFoundException {
+    }
+}
+}}}
+
+此一內部類別會引發
+java.lang.RuntimeException: java.lang.NoSuchMethodException: WordIndex$wordindexM.<init>()
+
+問題出在
+
+宣告內部類別的  map 或 reduce 的class 前面沒有宣告 static public ，因此正確的應該如下
+
+{{{
+#!java
+public class HelloHadoop {
+
+        static public class HelloMapper extends
+                        Mapper<LongWritable, Text, LongWritable, Text> {
+....
+        }
+
+        static public class HelloReducer extends
+                        Reducer<LongWritable, Text, LongWritable, Text> {
+...
+                }
+        }
+
+        public static void main(String[] args) throws IOException,
+                        InterruptedException, ClassNotFoundException {
+    }
+}
+}}}