Lucene : How to get LongField from index

Question

I add a LongField into index.

The method

IndexSearcher.doc() 

returns a document, within which all fields are either

org.apache.lucene.document.Field or org.apache.lucene.document.StoredField

How do I get a document from index with same field type as I put into. So then I copy this document to another index with the same field type.

Answer 1

At last , I find another method IndexSearcher.doc(int, StoredFieldVisitor) (I am using lucene 4.3)

And create a custom StoredFieldVisitor

public class StaySameFieldVisitor extends DocumentStoredFieldVisitor {
@Override
public void intField(FieldInfo fieldInfo, int value) {
    getDocument().add(new IntField(fieldInfo.name, value, Store.YES));
}

@Override
public void longField(FieldInfo fieldInfo, long value) {
    getDocument().add(new LongField(fieldInfo.name, value, Store.YES));
}

@Override
public void doubleField(FieldInfo fieldInfo, double value) {
    getDocument().add(new DoubleField(fieldInfo.name, value, Store.YES));
}

@Override
public void floatField(FieldInfo fieldInfo, float value) {
    getDocument().add(new FloatField(fieldInfo.name, value, Store.YES));
}

}