Cursor (Google App Engine API for Java)

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<Entity> nextBatch = preparedQuery.asQueryResultList(withLimit(20).cursor(decoded));
   

  See Also:

  Serialized Form

• • Method Summary

    All Methods Static Methods Instance Methods Concrete Methods Deprecated Methods 

    Modifier and Type	Method and Description
    boolean	equals(java.lang.Object obj)
    static Cursor	fromWebSafeString(java.lang.String encodedCursor) Decodes the given encoded cursor
    int	hashCode()
    Cursor	reverse() Deprecated.  It is no longer necessary to call reverse() on cursors. A cursor returned by a query may also be used in the query returned by Query.reverse().
    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

    • reverse

      @Deprecated
      public Cursor reverse()

      Deprecated. It is no longer necessary to call reverse() on cursors.

      A cursor returned by a query may also be used in the query returned by Query.reverse().

      Returns:

      a cursor identical to this

    • 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