gov.usgs.earthquake.nshmp.geo.json

Class GeoJson

java.lang.Object

gov.usgs.earthquake.nshmp.geo.json.GeoJson

public abstract class GeoJson
extends Object

Entry point for creating and parsing GeoJSON features and feature collections.

To create a GeoJSON feature collection string, use a builder and add features per the example below:

 String geojson = GeoJson.builder()
     .add(Feature.point(Location.create(34, -117))
         .id("featureId")
         .properties(ImmutableMap.of(
             "title", "Feature Title",
             "color", "#ff0080"))
         .build())
     .add(Feature.polygon(
         LocationList.create(
             Location.create(34, -117),
             Location.create(35, -118),
             Location.create(37, -116),
             Location.create(38, -117)))
         .id(3)
         .build())
     .toJson();
 

Where the GeoJSON string created is:

 {
   "type": "FeatureCollection",
   "features": [
     {
       "type": "Feature",
       "id": "featureId",
       "geometry": {
         "type": "Point",
         "coordinates": [-117.0, 34.0]
       },
       "properties": {
         "title": "Feature Title",
         "color": "#ff0080"
       }
     },
     {
       "type": "Feature",
       "id": 3,
       "geometry": {
         "type": "Polygon",
         "coordinates": [
           [
             [-117.0, 34.0],
             [-118.0, 35.0],
             [-116.0, 37.0],
             [-117.0, 38.0]
           ]
         ]
       },
       "properties": {}
     }
   ]
 }
 

A builder can also write directly to a specified path.

Note in the example above that features have their own geometry-specific builders. Feature builders also supply toJson() and write(Path) methods to output single-feature GeoJSON directly.

Parse GeoJSON to a feature or feature collection using static from* methods as follows:

 Feature f = GeoJson.from(stringOrPathOrUrl).toFeature();
 FeatureCollection fc = GeoJson.from(stringOrPathOrUrl).toFeatureCollection();
 

Once parsed, the feature geometry may be accessed as objects in the geo package (e.g. Location, LocationList, etc...). This requires some prior knowledge of the contents of the parsed GeoJSON.

This class does not allow the creation of empty feature collections or features with null geometry.

Author:

Peter Powers, Brandon Clayton

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GeoJson.Builder A GeoJSON builder.
static class	GeoJson.Type GeoJSON type identifier.

Method Summary

Modifier and Type	Method and Description
static GeoJson.Builder	builder() A reusable GeoJSON builder.
static GeoJson	from(Path json) Create a GeoJSON from a file path.
static GeoJson	from(String json) Create a GeoJSON from a string.
static GeoJson	from(URL json) Create a GeoJSON from a URL.
abstract Feature	toFeature() Return this GeoJson as a Feature.
abstract FeatureCollection	toFeatureCollection() Return this GeoJson as a FeatureCollection.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

toFeature

public abstract Feature toFeature()

Return this GeoJson as a Feature.

toFeatureCollection

public abstract FeatureCollection toFeatureCollection()

Return this GeoJson as a FeatureCollection.

from

public static GeoJson from(String json)

Create a GeoJSON from a string.

Parameters:

json - string to read

from

public static GeoJson from(Path json)

Create a GeoJSON from a file path.

Parameters:

json - file path to read

from

public static GeoJson from(URL json)

Create a GeoJSON from a URL. Use this method when reading resources from a JAR.

Parameters:

json - URL to read

builder

public static GeoJson.Builder builder()

A reusable GeoJSON builder.