Larry White created ARROW-17530:
-----------------------------------
Summary: [Java] VectorSchemaRoot#addVector() cannot add a vector
to the end of the current vector collection
Key: ARROW-17530
URL: https://issues.apache.org/jira/browse/ARROW-17530
Project: Apache Arrow
Issue Type: Improvement
Components: Java
Affects Versions: 9.0.0, 9.0.1
Reporter: Larry White
Assignee: Larry White
The current implementation of Java VectorSchemaRoot cannot add a vector at the
end of the current list (which is the generally understood meaning of "add").
The Precondition check in the method's second line prevents providing an
appropriate index for adding at the end:
{code:java}
public VectorSchemaRoot addVector(int index, FieldVector vector) {
Preconditions.checkNotNull(vector);
Preconditions.checkArgument(index >= 0 && index < fieldVectors.size());
List<FieldVector> newVectors = new ArrayList<>();
for (int i = 0; i < fieldVectors.size(); i++) {
if (i == index) {
newVectors.add(vector);
}
newVectors.add(fieldVectors.get(i));
}
return new VectorSchemaRoot(newVectors);
}
{code}
One possible implementation resolving the issue is shown below.
{code:java}
public VectorSchemaRoot addVector(int index, FieldVector vector) {
Preconditions.checkNotNull(vector);
Preconditions.checkArgument(index >= 0 && index <= fieldVectors.size());
List<FieldVector> newVectors = new ArrayList<>();
if (index == fieldVectors.size()) {
newVectors.addAll(fieldVectors);
newVectors.add(vector);
} else {
for (int i = 0; i < fieldVectors.size(); i++) {
if (i == index) {
newVectors.add(vector);
}
newVectors.add(fieldVectors.get(i));
}
}
return new VectorSchemaRoot(newVectors);
}
{code}
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