api:dk11:java:tatukgis.jdk.tgis_layervector.findfirst_tgis_extent_string
Table of Contents
TGIS_LayerVector.FindFirst(TGIS_Extent, java.lang.String) method
DK11 for Java | tatukgis.jdk.TGIS_LayerVector.FindFirst | Overloads | Constructors | Fields | Methods | Properties | Events
Finds the first occurrence of an item which meets an extent and query. Will use RTree if available.
Syntax
// Java public TGIS_Shape FindFirst( TGIS_Extent _extent, java.lang.String _query );
// Oxygene public function FindFirst( _extent : TGIS_Extent; _query : String ) : TGIS_Shape; virtual;
Parameters
| Name | Type | Description |
|---|---|---|
| _extent | TGIS_Extent | extent of items to be found; the layer has been attached to the Viewer then expected _extent units are in a Viewer coordinate space; otherwise expected _extent units are in a Layer coordinate space |
| _query | java.lang.String String | query which must be matched by item; closely mimics SQL WHERE clause; for examples you can use 'AGE >= 18'; empty (default) means that no items will match. |
Result
| Type | Description |
|---|---|
| TGIS_Shape | Shape itself or nil. |
Remarks
See: FindNext
Use this method to find to the first shape in the layer matching given criteria. Using _query param we can narrow the result of the shape searching down to the minimum. This should speed up our process of locating a desired shape.
To locate a shape, simply choose an existing layer and use FindFirst method of with a proper extent and a SQL query as a WHERE clause.
References
2022/11/16 01:49