Databases
StackOverflow2013
Postsdbo
POHow to reference subclasses of static Java classes with generics in Scala
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to reference subclasses of static Java classes with generics in Scala
    primarykey
    data
    text
    <p>I have this Java code:</p> <pre><code>public class TestMapper extends AppEngineMapper&lt;Key, Entity, NullWritable, NullWritable&gt; { public TestMapper() { } // [... other overriden methods ...] @Override public void setup(Context context) { log.warning("Doing per-worker setup"); } } </code></pre> <p>...which I've converted to:</p> <pre><code>class TestMapper extends AppEngineMapper[Key, Entity, NullWritable, NullWritable] { // [... other overriden methods ...] override def setup(context: Context) { log.warning("Doing per-worker setup") } } </code></pre> <p><strong>Now the actual problem:</strong> </p> <p><strong><em>Context</em></strong> is defined as a nested class within the <strong>org.apache.hadoop.mapreduce.Mapper</strong> class:</p> <pre><code> public static class Mapper&lt;KEYIN, VALUEIN, KEYOUT, VALUEOUT&gt; { //[... some other methods ...] protected void setup(org.apache.hadoop.mapreduce.Mapper&lt;KEYIN,VALUEIN,KEYOUT,VALUEOUT&gt;.Context context) throws java.io.IOException, java.lang.InterruptedException { /* compiled code */ } public class Context extends org.apache.hadoop.mapreduce.MapContext&lt;KEYIN,VALUEIN,KEYOUT,VALUEOUT&gt; { public Context(org.apache.hadoop.conf.Configuration configuration, org.apache.hadoop.mapreduce.TaskAttemptID conf, org.apache.hadoop.mapreduce.RecordReader&lt;KEYIN,VALUEIN&gt; taskid, org.apache.hadoop.mapreduce.RecordWriter&lt;KEYOUT,VALUEOUT&gt; reader, org.apache.hadoop.mapreduce.OutputCommitter writer, org.apache.hadoop.mapreduce.StatusReporter committer, org.apache.hadoop.mapreduce.InputSplit reporter) throws java.io.IOException, java.lang.InterruptedException { /* compiled code */ } } </code></pre> <p>So I can't tell my Scala class where/what <strong>Context</strong> actually is. If <strong>Mapper</strong> had no generics I could reference <strong>Context</strong> via </p> <pre><code>Mapper#Context </code></pre> <p>but how can I tell that Mapper has Generics? </p> <pre><code>Mapper[_,_,_,_]#Context </code></pre> <p>...didn't work.</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USAlex
    1. USAlex
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to reference subclasses of static Java classes with generics in Scala
      1. USAlex
      1. VTFavorite
    2. VO
      singulars
      1. POHow to reference subclasses of static Java classes with generics in Scala
      1. USAlexey Romanov
      1. VTFavorite
    3. VO
      singulars
      1. POHow to reference subclasses of static Java classes with generics in Scala
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThank you a lot for the question, I've spent several hours on exactly these classes!
      singulars
      1. POHow to reference subclasses of static Java classes with generics in Scala
      1. USDzmitry Lazerka
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload