Added event sample.

Author: Petter Hesselberg

android/app/src/main/java/com/demo/activity/ActivityStarterModule.java

@@ -14,18 +14,32 @@
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.bridge.ReactMethod;
 import com.facebook.react.bridge.WritableNativeArray;
+import com.facebook.react.bridge.WritableNativeMap;
+import com.facebook.react.modules.core.DeviceEventManagerModule;
+
+import java.util.HashMap;
+import java.util.Map;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Expose Java to JavaScript.
  */
 class ActivityStarterModule extends ReactContextBaseJavaModule {
 
+    private static DeviceEventManagerModule.RCTDeviceEventEmitter eventEmitter = null;
+
     ActivityStarterModule(ReactApplicationContext reactContext) {
         super(reactContext);
     }
 
+    @Override
+    public void initialize() {
+        super.initialize();
+        eventEmitter = getReactApplicationContext().getJSModule(DeviceEventManagerModule.RCTDeviceEventEmitter.class);
+    }
+
     /**
      * @return the name of this module. This will be the name used to {@code require()} this module
      * from JavaScript.
@@ -35,6 +49,14 @@ public String getName() {
         return "ActivityStarter";
     }
 
+    @Nullable
+    @Override
+    public Map<String, Object> getConstants() {
+        final Map<String, Object> constants = new HashMap<>();
+        constants.put("MyEventName", "MyEventValue");
+        return constants;
+    }
+
     @ReactMethod
     void navigateToExample() {
         Activity activity = getCurrentActivity();
@@ -86,4 +108,11 @@ void callJavaScript() {
             }
         }
     }
+
+    /**
+     * To pass an object instead of a simple string, create a {@link WritableNativeMap} and populate it.
+     */
+    static void triggerAlert(@Nonnull String message) {
+        eventEmitter.emit("MyEventValue", message);
+    }
 }

android/app/src/main/java/com/demo/activity/ActivityStarterReactPackage.java

@@ -1,7 +1,6 @@
 package com.demo.activity;
 
 import com.facebook.react.ReactPackage;
-import com.facebook.react.bridge.JavaScriptModule;
 import com.facebook.react.bridge.NativeModule;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.uimanager.ViewManager;

android/app/src/main/java/com/demo/activity/ExampleActivity.java

@@ -1,23 +1,30 @@
 package com.demo.activity;
 
 import android.os.Bundle;
-import android.support.v7.app.AppCompatActivity;
 import android.view.View;
 
+import com.facebook.react.ReactActivity;
 
-public class ExampleActivity extends AppCompatActivity {
+public class ExampleActivity extends ReactActivity {
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_example);
 
-        View goBack = findViewById(R.id.go_back_btn);
-        goBack.setOnClickListener(new View.OnClickListener() {
+        findViewById(R.id.call_callback_btn).setEnabled(true);
+        findViewById(R.id.go_back_btn).setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View view) {
                 onBackPressed();
             }
         });
+
+        findViewById(R.id.call_callback_btn).setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                ActivityStarterModule.triggerAlert("Hello from " + getClass().getSimpleName());
+            }
+        });
     }
 }

android/app/src/main/res/layout/activity_example.xml

@@ -22,7 +22,15 @@
         android:layout_gravity="center"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
+        android:layout_marginBottom="12dp"
         android:text="@string/go_back"
     />
+    <Button
+        android:id="@+id/call_callback_btn"
+        android:layout_gravity="center"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/trigger_event"
+    />
 
 </LinearLayout>

android/app/src/main/res/values/strings.xml

@@ -4,4 +4,5 @@
     <string name="example_activity_title">Example activity</string>
     <string name="go_back">Go back!</string>
     <string name="call_javascript_method">Call JavaScript method</string>
+    <string name="trigger_event">Trigger event</string>
 </resources>

index.android.js

@@ -8,6 +8,7 @@ import React, { Component } from 'react';
 import {
   AppRegistry,
   Button,
+  NativeEventEmitter,
   NativeModules,
   StyleSheet,
   Text,
@@ -25,6 +26,8 @@ export class ExposedToJava {
 const exposedToJava = new ExposedToJava();
 BatchedBridge.registerCallableModule("JavaScriptVisibleToJava", exposedToJava);
 
+const activityStarter = NativeModules.ActivityStarter;
+
 export default class ActivityDemoComponent extends Component {
   render() {
     return (
@@ -41,21 +44,21 @@ export default class ActivityDemoComponent extends Component {
         </Text>
         <View style={styles.buttonContainer}>
           <Button
-            onPress={() => NativeModules.ActivityStarter.navigateToExample()}
+            onPress={() => activityStarter.navigateToExample()}
             title='Start example activity'
           />
           <Button
-            onPress={() => NativeModules.ActivityStarter.dialNumber('+1 (234) 567-8910')}
+            onPress={() => activityStarter.dialNumber('+1 (234) 567-8910')}
             title='Dial +1 (234) 567-8910'
           />
           <Button
-            onPress={() => NativeModules.ActivityStarter.getActivityName((name) => { alert(name); })}
+            onPress={() => activityStarter.getActivityName((name) => { alert(name); })}
             title='Get activity name'
           />
           <Button
             onPress={async () => {
               try {
-                var name = await NativeModules.ActivityStarter.getActivityNameAsPromise();
+                var name = await activityStarter.getActivityNameAsPromise();
                 alert(name);
                 } catch (e) {
                   alert(e.message);
@@ -68,7 +71,7 @@ export default class ActivityDemoComponent extends Component {
             title='Copy to clipboard'
           />
           <Button
-            onPress={() => NativeModules.ActivityStarter.callJavaScript()}
+            onPress={() => activityStarter.callJavaScript()}
             title='Call JavaScript from Java'
           />
         </View>
@@ -103,3 +106,6 @@ const styles = StyleSheet.create({
 });
 
 AppRegistry.registerComponent('ActivityDemoComponent', () => ActivityDemoComponent);
+
+const eventEmitter = new NativeEventEmitter(activityStarter);
+eventEmitter.addListener(activityStarter.MyEventName, (params) => alert(params));