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intermediate

The Java API wrapper is useful for Java developers who wish to seamlessly integrate the what3words API into their Java applications, without the hassle of having to manage the low level API calls themselves.

A full example of how to integrate the what3words Java wrapper is available in our
Java Github repository

1Get API key

2Installation

The library is available through Maven Central. Please add one of the following to either your pom.xml or gradle.build files.

Maven:

<dependency>
  <groupId>com.what3words</groupId>
  <artifactId>w3w-java-wrapper</artifactId>
  <version>3.1.17</version>
</dependency>

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Using Gradle:

implementation 'com.what3words:w3w-java-wrapper:3.1.17'

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3Setup

Instantiate an instance of What3WordsV3, from which all API requests can be made

// For all requests a what3words API key is needed
What3WordsV3 api = new What3WordsV3("what3words-api-key");

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In the case that you run our Enterprise Suite API Server yourself, you may specify the URL to your server like so:

// In the case that you run our Enterprise Suite API Server yourself, you may specify the URL to your own server like so:
What3WordsV3 api = new What3WordsV3("what3words-api-key", "https://api.yourserver.com/v3/");

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Additionally, if you run the Enterprise Suite API Server there is another optional setup() parameter: customHeaders. Use this if you need to send custom headers to your server:

/**
 * Additionally, if you run the Enterprise Suite API Server there is another optional setup() parameter: customHeaders. 
 * Use this if you need to send custom headers to your own server:
 */
Map<String, String> headers = new HashMap<String, String>();
headers.put("Name1", "Value1");
headers.put("Name2", "Value2");
What3WordsV3 api = new What3WordsV3("what3words-api-key", "https://api.yourserver.com/v3/", headers);

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5Usage

Convert to what3words address

This function converts coordinates (expressed as latitude and longitude) to a what3words address.

More information about ConvertTo3wa, including returned results is available in the what3words REST API documentation.

Find the words for (51.484463, -0.195405):

// Convert coordinates to a 3 word address
ConvertTo3WA words = api.convertTo3wa(new Coordinates(51.484463, -0.195405))
    .language("en")
    .execute();
System.out.println("Words: " + words);

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Convert to coordinates

This function converts a what3words address to a position, expressed as coordinates of latitude and longitude.

It takes the words parameter as a string of a what3words 'table.book.chair'

More information about ConvertToCoordinates, including returned results is available in the what3words REST API documentation.

Find the words for ///filled.count.soap:

// Convert a 3 word address to coordinates
ConvertToCoordinates coordinates = api.convertToCoordinates("filled.count.soap")
    .execute();
System.out.println("Coordinates: " + coordinates);

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AutoSuggest

When presented with a what3words address which may be incorrectly entered, AutoSuggest returns a list of potential correct 3 word addresses. It needs the first two words plus at least the first character of the third word to produce suggestions.

This method provides corrections for mis-typed words (including plural VS singular), and words being in the wrong order.

Optionally, clipping can narrow down the possibilities, and limit results to:

One or more countries
A geographic area (a circle, box or polygon)

This dramatically improves results, so we recommend that you use clipping if possible.

To improve results even further, set the Focus to user’s current location. This will make AutoSuggest return results which are closer to the user.

More information about AutoSuggest, including returned results is available in the what3words REST API documentation.

Code example Simple basic call:

Autosuggest autosuggest = api.autosuggest("fun.with.code")
    .execute();
System.out.println("Autosuggest: " + autosuggest);

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Code example AutoSuggest, clipping the results returned to the United Kingdom and Belgium:

Autosuggest autosuggest = api.autosuggest("fun.with.code")
    .clipToCountry("GB", "BE")
    .execute();
System.out.println("Autosuggest: " + autosuggest);

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Code example AutoSuggest, Focus on (51.4243877,-0.34745).

Autosuggest autosuggest = api.autosuggest("fun.with.code")
    .focus(new Coordinates(51.4243877,-0.34745))
    .execute();
System.out.println("Autosuggest: " + autosuggest);

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Code example AutoSuggest, with Generic Voice input type.

Autosuggest autosuggest = api.autosuggest("fun with code")
    .inputType(AutosuggestInputType.GENERIC_VOICE)
    .language("en")
    .execute();
System.out.println("Autosuggest: " + autosuggest);

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Grid section

Grid section returns a section of the what3words 3m x 3m grid as a set of horizontal and vertical lines covering the requested area, which can then be drawn onto a map.

The requested box must not exceed 4km from corner to corner, or a BadBoundingBoxTooBig error will be returned.

More information about GridSection, including returned results is available in the what3words REST API documentation.

Get a grid for (51.527649, -0.191746) in the south-west, and (51.515900, -0.212517 in the north-east:

// Obtain a grid section within the provided bounding box
GridSection gridSection = api.gridSection(
      new BoundingBox(
          new Coordinates(51.515900, -0.212517), 
          new Coordinates(51.527649, -0.191746)
      )
  ).execute();
System.out.println("Grid section: " + gridSection);

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Serializing To GeoJSON

If GeoJSON format is required (you are using on a map in an app for example) a function such as geoJsonSerializer can be added. This should be registered to Gson as a TypeAdapter and then you can then serialize the objects returned from the wrapper into GeoJSON.

JsonSerializer<GridSection> geoJsonSerializer = api.getGridSectionJsonSerializer();
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.registerTypeAdapter(GridSection.class, geoJsonSerializer);
Gson geoJsonGson = gsonBuilder.create();  
String geoJson = geoJsonGson.toJson(gridSection);

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Available languages

This function returns the currently supported languages. It will return the two letter code, and the name of the language both in that language and in English.

More information about AvailableLanguages, including returned results is available in the what3words REST API documentation.

// Obtain the list of available languages
AvailableLanguages languages = api.availableLanguages().execute();
System.out.println("Languages: " + languages);

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Handling errors

Errors returned from the API can be caught with the wrapper through the use of a catch function.

Within the catch function, code and message values which represent the error, are accessible from the error object parameter

Autosuggest autosuggest = api.autosuggest("freshen.overlook.clo")
    .clipToCountry("fr")
    .execute();

if (autosuggest.isSuccessful()) {
    ...
} else { // An error occurred
    What3WordsError error = autosuggest.getError();

    if (error == What3WordsError.BAD_CLIP_TO_COUNTRY) { // Invalid country clip is provided
        System.out.println("BadClipToCountry: " + error.getMessage());
    }
}

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6RegEx Functions

This section introduces RegEx functions that can assist with checking and finding possible what3words addresses in strings. The three main functions covered are:

isPossible3wa – Match what3words address format;
isValid3wa – Verify a what3words address with the API;

isPossible3wa

Our API wrapper RegEx function “isPossible3wa” can be used to detect if a text string (like “filled.count.soap“) in the format of a what3words address without having to ask the API. This functionality checks if a given string could be a what3words address. It returns true if it could be, otherwise false.

Note: This function checks the text format but not the validity of a what3words address. Use isValid3wa to verify validity.

public class What3WordsExample {
    public static void main(String[] args) {
        // Example what3words addresses
        String[] addresses = {"filled.count.soap", "not a 3wa", "not.3wa address"};

        // Check if the addresses are possible what3words addresses
        for (String address : addresses) {
            boolean isPossible = What3WordsV3.isPossible3wa(address);
            System.out.println("Is '" + address + "' a possible what3words address? " + isPossible);
        }
    }
}

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Expected Output

isPossible3wa(“filled.count.soap”) returns true
isPossible3wa(“not a 3wa”) returns false
isPossible3wa(“not.3wa address”)returns false

isValid3wa

Our API wrapper RegEx function “isValid3wa” can be used to determine if a string is a valid what3words address by checking it against the what3words RegEx filter and verifying it with the what3words API.

public class What3WordsExample {
    public static void main(String[] args) {
		
		// Initialize the What3Words API with your API key
        What3WordsV3 api = new What3WordsV3("YOUR_API_KEY");
        
		// Example addresses
        String[] addresses = {
            "filled.count.soap",
    		"filled.count.",
    		"coding.is.cool"
        };

        // Check if the addresses are valid what3words addresses
        for (String address : addresses) {
            boolean response = api.isValid3wa(address);
            if (response.isSuccessful() && response.getIsValid()) {
                System.out.println(address + " is a valid what3words address");
            } else if (response.isSuccessful() && !response.getIsValid()) {
                System.out.println(address + " is an invalid what3words address");
            } else {
                System.out.println("isValid3wa error: " + response.getError().getKey() + " " +  response.getError().getMessage());
            }
        }
    }
}

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Expected Outputs

isValid3wa(“filled.count.soap”) returns True
isValid3wa(“filled.count.”) returns False
isValid3wa(“coding.is.cool”) returns False

Also make sure to replace <YOUR_API_KEY> with your actual API key. These functionalities provide different levels of validation for what3words addresses, from simply identifying potential addresses to verifying their existence on Earth.

7Troubleshooting

If you encounter errors or issues related to convert-to-coordinate, convert-to-3wa and grid-section requests while using the Free plan, please check the network panel for the following error message Error 402 payment required and its response, indicating the need to upgrade to a higher plan:

{
    "error": {
        "code": "QuotaExceeded",
        "message": "Quota exceeded or API plan does not have access to this feature. Please change your plan at https://accounts.what3words.com/select-plan, or contact support@what3words.com"
    }
}

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For more information, visit our API plans page. If you need further assistance, contact support@what3words.com.

8Full example

The example below takes the concepts described above, and turns some of them into a complete example. Here we take a partial 3 word address and pass it into AutoSuggest – clipping the results to consider only addresses in France, setting a focus of Paris, and returning a single result

We then take the result and convert the 3 word address to coordinates, and find the nearest place.

// For all requests a what3words API key is needed
What3WordsV3 api = new What3WordsV3("what3words-api-key");

Autosuggest autosuggest = api.autosuggest("freshen.overlook.clo")
    .clipToCountry("FR")
    .focus(new Coordinates(48.856618, 2.3522411))
    .nResults(1)
    .execute();

if (autosuggest.isSuccessful()) {
    String words = autosuggest.getSuggestions().get(0).getWords();
    System.out.printf("Top 3 word address match: %s%n", words);
    
    ConvertToCoordinates convertToCoordinates = api.convertToCoordinates(words).execute();
    if (convertToCoordinates.isSuccessful()) {
        System.out.printf("WGS84 Coordinates: %f, %f%n", 
                convertToCoordinates.getCoordinates().getLat(), 
                convertToCoordinates.getCoordinates().getLng());
        System.out.printf("Nearest Place: %s%n", convertToCoordinates.getNearestPlace());                
    } else {
        What3WordsError error = autosuggest.getError();
        if (error == What3WordsError.INTERNAL_SERVER_ERROR) { // Server Error
            System.out.println("InternalServerError: " + error.getMessage());

        } else if (error == What3WordsError.NETWORK_ERROR) { // Network Error
            System.out.println("NetworkError: " + error.getMessage());

        }
    }
} else {
    What3WordsError error = autosuggest.getError();

    if (error == What3WordsError.BAD_CLIP_TO_COUNTRY) { // Invalid country clip is provided
        System.out.println("BadClipToCountry: " + error.getMessage());

    } else if (error == What3WordsError.BAD_FOCUS) { // Invalid focus
        System.out.println("BadFocus: " + error.getMessage());

    } else if (error == What3WordsError.BAD_N_RESULTS) { // Invalid number of results
        System.out.println("BadNResults: " + error.getMessage());

    } else if (error == What3WordsError.INTERNAL_SERVER_ERROR) { // Server Error
        System.out.println("InternalServerError: " + error.getMessage());

    } else if (error == What3WordsError.NETWORK_ERROR) { // Network Error
        System.out.println("NetworkError: " + error.getMessage());

    } else {
        System.out.println(error + ": " + error.getMessage());

    }
}

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Server and Scripting Add 3 word addresses to a voice assistant Add a 3 word address input field Batch convert 3 word addresses or co-ordinates Use 3 word addresses with a map Use 3 word addresses with voice input Use 3 word addresses within a GIS Use 3 word addresses within an address search Java

Developer

All tutorials

Java

Convert to what3words address

Convert to coordinates

AutoSuggest

Grid section

Serializing To GeoJSON

Available languages

Handling errors

isPossible3wa

Expected Output

isValid3wa

Expected Outputs

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