[AVRO-1680] Problems with code snippet in Decoder#readMapStart javadocs

• Type: Improvement
• Status: Open
• Priority: Trivial
• Resolution: Unresolved
• Affects Version/s: 1.7.7
• Component/s: doc, java
• Labels: beginner
• Assignee: Unassigned
• Reporter: Eugene Kirpichov
• Created: 09/Jun/15 20:55
• Updated: 18/Aug/17 13:49

Description

https://github.com/apache/avro/blob/trunk/lang/java/avro/src/main/java/org/apache/avro/io/Decoder.java javadocs ( http://avro.apache.org/docs/1.7.7/api/java/org/apache/avro/io/Decoder.html#readMapStart() ) say:

    Map m = new HashMap();
    Record reuse = new Record();
    for(long i = in.readMapStart(); i != 0; i = in.readMapNext()) {
      for (long j = 0; j < i; j++) {
        String key = in.readString();
        reuse.intField = in.readInt();
        reuse.boolField = in.readBoolean();
        m.put(key, reuse);
      }
   }

This can be improved in two ways:
1) Javadoc ate the generic arguments. This can be fixed by wrapping into {@code}.
2) The mutable record object is being reused; as a result, the map will have the same shared object mapped to every key. I don't think this is likely to be the user's intention, so a new Record should be created on every iteration.

Actually in 3 ways.
3) a much better name for "i" would be "numRecords", because otherwise it seems like "j" and "i" have similar roles (indices over some containers), which they don't - "i" is not an index into any container, only j is. Then "j" can be renamed to "i".