Exercise code 3-2 secrets of Android Application Development

Public void oncreate (bundle savedinstancestate)
{
Textview TV = new textview (this );
String string = "";
Super. oncreate (savedinstancestate );
// Obtain the contentresolver object
Contentresolver Cr = getcontentresolver ();
// Obtain the cursor for the first entry in the phone book
Cursor cursor = Cr. Query (contactscontract. Contacts. content_uri, null );
While (cursor. movetonext ())
{
Try {
Int idcolumn = cursor. getcolumnindex (contactscontract. Contacts. _ id );
String contactid = cursor. getstring (idcolumn );
// Obtain the contact name
Int namefieldcolumnindex = cursor. getcolumnindex (phonelookup. display_name );
String contact = cursor. getstring (namefieldcolumnindex );
// Obtain the phone number
String phonenumber = "";
// Obtain the contact number
Int phonecount = cursor. getint (cursor. getcolumnindex (contactscontract. Contacts. has_phone_number ));
If (phonecount> 0 ){
// Obtain the contact's phone number
Cursor phones = getcontentresolver (). Query (
Contactscontract. commondatakinds. Phone. content_uri, null,
Contactscontract. commondatakinds. Phone. contact_id + "=" + contactid,
Null, null );
If (phones. movetofirst ()){
Do {
// Traverse all phone numbers
Phonenumber + = phones. getstring (phones. getcolumnindex (
Contactscontract. commondatakinds. Phone. Number) + "\ t ";
System. Out. println (phonenumber );
} While (phones. movetonext ());
}
}
String + = Contact + ":" + phonenumber + "\ n ";
} Catch (exception ex ){
Ex. printstacktrace ();
}

// Cursor. movetonext ();
}
Cursor. Close ();
// Set the content displayed in textview
TV. settext (string );
// Display to the screen
Setcontentview (TV );
}