Using Union tool in ArcObjects?

Question

I am currently working with the Union tool of ArcObjects but I do not know how to properly pass the input_features to the union object. I ́ve tried several methods but all throw an Automation Exception (0x80004005 - Unspecified Error). I could not find a single sample for the Union tool in Java.

 GeoProcessor geoProcessor = null;
 try {
 geoProcessor = new GeoProcessor();
 geoProcessor.setOverwriteOutput(true);
 // Get featureclass objects of both shapes
 IWorkspaceFactory workspaceFactory = new ShapefileWorkspaceFactory();
 IWorkspace workspace = workspaceFactory.openFromFile("C:\\test", 0);
 IFeatureWorkspace featureWorkspace = (IFeatureWorkspace) workspace;
 IFeatureClass fc1 = featureWorkspace.openFeatureClass("a.shp");
 IFeatureClass fc2 = featureWorkspace.openFeatureClass("b.shp");
 // Create IGPValueTableObject and and add featureclasses
 IGpValueTableObject gpvtObject = new GpValueTableObject();
 gpvtObject.setColumns(2);
 gpvtObject.setRow(0, fc1);
 gpvtObject.setValue(0, 1, 1);
 gpvtObject.setRow(1, fc2);
 gpvtObject.setValue(1, 1, 2);
 /*
 * Also tried this:
 * gpvtObject.addRow(fc1);
 * gpvtObject.addRow(fc2);
 */
 Union union = new Union();
 union.setInFeatures(gpvtObject);
 union.setOutFeatureClass("C:\\test\\union.shp");
 geoProcessor.execute(union, null);
 } catch (IOException e) {
 e.printStackTrace();
 }

Answer 1

It looks like the input features are specified as follows:

"X #;Y #;Z #;"

Where X, Y, and Z are either a layer or a path to a feature class and '#' is either a number representing the rank of the feature class or '#' if the feature class has no rank.

So your input would be something like:

"C:\test\a.shp #; C:\test\b.shp #"

I found this by running Union in ArcMap and looking at the Geoprocessing Results window message which lists the input arguments.

• David: Your answer really helped me! I´ve tried it and if I specify my input features like this it works: "'X' #; 'Y' #" --- "'C:\test\a.shp' #; 'C:\test\b.shp' #"