com.google.appengine.api.datastore
Class Cursor

java.lang.Object
  com.google.appengine.api.datastore.Cursor

All Implemented Interfaces:

java.io.Serializable

public final class Cursor
extends java.lang.Object
implements java.io.Serializable

A cursor that represents a position in a query. To resume a Query at the position defined by a Cursor, the Cursor must be present in the FetchOptions passed to a PreparedQuery identical to the one it was created from.

Cursors can be retrieved from PreparedQuery.asQueryResult* functions. A typical use case would be:

 Cursor originalCursor = preparedQuery.asQueryResultList(withLimit(20)).getCursor();
 String encodedCursor = original.toWebSafeString();
 

The encoded cursor can then be passed safely in a get or post arg of a web request and on another request the next batch of results can be retrieved with:

 Cursor decodedCursor = Cursor.fromWebSafeString(encodedCursor);
 List nextBatch = preparedQuery.asQueryResultList(withLimit(20).cursor(decoded));
 

See Also:

Serialized Form

Method Summary

boolean	equals(java.lang.Object obj)
static Cursor	fromWebSafeString(java.lang.String encodedCursor) Decodes the given encoded cursor
int	hashCode()
java.lang.String	toString()
java.lang.String	toWebSafeString() Encodes the current cursor as a web safe string that can later be decoded by fromWebSafeString(String)

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Method Detail

toWebSafeString

public java.lang.String toWebSafeString()

Encodes the current cursor as a web safe string that can later be decoded by fromWebSafeString(String)

fromWebSafeString

public static Cursor fromWebSafeString(java.lang.String encodedCursor)

Decodes the given encoded cursor

Parameters:

encodedCursor -

Returns:

the decoded cursor

Throws:

java.lang.IllegalArgumentException - if the provided string is not a valid encoded cursor

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object