Add a simple tool call example

CONTRIBUTING.md

@@ -6,7 +6,22 @@ modify the contents of the `arcade-java/lib/` and `arcade-java-examples/` direct
 
 ## Adding and running examples
 
-TODO
+Set the following environment variables:
+
+| ENV Var           | Description                                                             |
+|-------------------|-------------------------------------------------------------------------|
+| `ARCADE_USER_ID`  | Arcade user Id or email address                                         |
+| `ARCADE_API_KEY`  | [Arcade API key](https://docs.arcade.dev/en/get-started/setup/api-keys) |
+| `ARCADE_BASE_URL` | Arcade URL, defaults to: `https://api.arcade.dev`                       |
+
+Use `./gradlew :arcade-java-example:run -Pexample=<Name>` to run `<Name>Example`
+
+For example, if you have the `potify.ResumePlayback` tool configured, you can run:
+```shell
+export ARCADE_API_KEY='your-api-key'
+export ARCADE_USER_ID='your-arcade-user'
+./gradlew :arcade-java-example:run -Pexample=PlaySpotify
+```
 
 ## Building the repository from source
 

arcade-java-example/src/main/java/dev/arcade/example/PlaySpotifyExample.java

@@ -0,0 +1,43 @@
+package dev.arcade.example;
+
+import dev.arcade.client.ArcadeClient;
+import dev.arcade.client.okhttp.ArcadeOkHttpClient;
+import dev.arcade.models.tools.ExecuteToolRequest;
+import dev.arcade.models.tools.ExecuteToolResponse;
+import dev.arcade.models.tools.ToolExecuteParams;
+
+/**
+ * Example of calling a tool using the Arcade Java SDK.
+ */
+public class PlaySpotifyExample {
+
+    /**
+     * Executes the Spotify.ResumePlayback, both the <code>ARCADE_USER_ID</code> and <code>ARCADE_API_KEY</code> environment variables must be set.
+     * See the <a href="https://docs.arcade.dev/en/get-started/setup/api-keys">Getting Your API Key</a> guide to create an API Key.
+     * Your username can be found in the lower left corner of your <a href="https://app.arcade.dev/home">Arcade console</a>.
+     * @param args Not used.
+     */
+    public static void main(String[] args) {
+
+        String userId = System.getenv("ARCADE_USER_ID"); // the Spotify tool requires a userId
+        if (userId == null) {
+            throw new IllegalArgumentException("ARCADE_USER_ID and ARCADE_API_KEY environment variables must be set");
+        }
+
+        // Configures using the `ARCADE_API_KEY` environment variable
+        ArcadeClient client = ArcadeOkHttpClient.fromEnv();
+
+        ToolExecuteParams params = ToolExecuteParams.builder()
+                .executeToolRequest(ExecuteToolRequest.builder()
+                        .toolName("Spotify.ResumePlayback@1.0.2")
+                        .userId(userId)
+                        .build())
+                .build();
+        ExecuteToolResponse executeToolResponse = client.tools().execute(params);
+        executeToolResponse
+                .output()
+                .ifPresentOrElse(
+                        output -> System.out.println("Tool output: " + output._value()),
+                        () -> System.out.println("No output for this tool"));
+    }
+}