how to set permission of google doc using its api? - google-docs-api

Question

I am new to google doc api, and using google doc api 3rd version with java ,
I m trying to share doc with permission and want to change permission on different call,
Here there is some code which i had designed to share persmission and update and delete permission , but some how i wil got some problem on each operation,
On first time i can share docs with permission , but once i had share and again try to share with other permission then it cant allow me to upda so what should be i missing at here ,
AclEntry acl = new AclEntry();
AclScope aclScope = new AclScope(AclScope.Type.USER,"xyz#gmail.com");
acl.setScope(aclScope);
//AclRole aclRole = new AclRole();
acl.setRole(AclRole.READER);
URL url = buildUrl(URL_DEFAULT + URL_DOCLIST_FEED + "/" + folderResId + URL_FOLDERS + "/" + entry.getResourceId());
System.out.println(url.toString());
System.out.println("url : "+entry.getAclFeedLink().getHref());
// For Insert
//service.insert(new URL(entry.getAclFeedLink().getHref()), acl);
// For Update
//service.getRequestFactory().setHeader("If-Match", "*");
//service.update(new URL(entry.getEditLink().getHref()), acl);
// For Delete
service.getRequestFactory().setHeader("If-Match", "*");
service.delete(new URL(entry.getEditLink().getHref()), aclScope);
after insert first tim eif itry to insert again i wil get this error..
com.google.gdata.util.VersionConflictException: This user already has access to the document.
After insert if i try to delete that then i wil get this error
com.google.gdata.util.InvalidEntryException: Unexpected resource version ID
thnaks in advance,

Answer 1

Just a comment about your first error message: according to my experience with this api, this is the behavior that is in fact expected, as long as you are trying to insert an acl record that is equivalent to an already existent one. In other words, you can't insert a duplicate of an existing acl record, you always get that exception when you try to do so.