Creating a folder in Dropbox

Yes, API v2 offers structured exceptions, so you can detect specific scenarios like this. The documentation for createFolder covers all of the types of exceptions it can throw.

For example, to detect this particular error case:

try {
    FolderMetadata folder = client.files().createFolder("/test_java_createFolder");
    System.out.println(folder.getName());
} catch (CreateFolderErrorException err) {
    if (err.errorValue.isPath() && err.errorValue.getPathValue().isConflict()) {
        System.out.println("Something already exists at the path.");
    } else {
        System.out.print("Some other CreateFolderErrorException occurred...");
        System.out.print(err.toString());
    }
} catch (Exception err) {
    System.out.print("Some other Exception occurred...");
    System.out.print(err.toString());
}