I found a lot of articles speaking about how to integrate react native into existing android apps. But none of them explains how to get a result back from the react native code in order to use it directly in Java android source code.
Explanations : I have a react native app that is doing a specific job and displays the result in a popup window. I want to integrate this app (doing the necessary modifications) to be able to get this specific result into my android Java source code instead of displaying it into a react native popup.
I searched all the internet but found nothing about this.
In order to get a result back from the activity you started, your module needs to have access to the reference of your activity.
Here are two solutions :
- Declare the module as an inner class of the activity
- Pass a reference of your activity in the constructor of the module
But, remember that your module needs to be used in a ReactPackage, and ReactPackage is an interface, so if you want you can have your ReactActivity implementing the interface (instead of creating a new class).
Here is a full working example using an inner class and an activity implementing ReactPackage :
public class MyReactActivity extends AppCompatActivity
implements DefaultHardwareBackBtnHandler, ReactPackage
{
private ReactRootView mReactRootView;
private ReactInstanceManager mReactInstanceManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mReactRootView = new ReactRootView(this);
mReactInstanceManager = ReactInstanceManager.builder()
.setApplication(getApplication())
.setBundleAssetName("index.android.bundle")
.setJSMainModuleName("index.android")
.addPackage(new MainReactPackage())
// This activity is also a "ReactPackage"
.addPackage(this)
.setUseDeveloperSupport(BuildConfig.DEBUG)
.setInitialLifecycleState(LifecycleState.RESUMED)
.build();
mReactRootView.startReactApplication(mReactInstanceManager, "MyReactComponent", null);
setContentView(mReactRootView);
}
@Override
public List<NativeModule> createNativeModules(ReactApplicationContext reactContext) {
List<NativeModule> modules = new ArrayList<>();
// The module is added to the ReactPackage
modules.add(new TestModule(reactContext));
return modules;
}
@Override
public List<ViewManager> createViewManagers(ReactApplicationContext reactContext) {
return Collections.emptyList();
}
// Module definition as an inner class
public class TestModule extends ReactContextBaseJavaModule {
public TestModule(ReactApplicationContext reactContext) {
super(reactContext);
}
@Override
public String getName() {
return "TestModule";
}
// The function you'll call from React Native
@ReactMethod
public void closewithresult(float datafromreact) {
// Set a result
Bundle bundle = new Bundle();
bundle.putFloat("result", datafromreact);
setResult(Activity.RESULT_OK, (new Intent()).putExtras(bundle));
// Close the activity
finish();
}
}
/*
* Other overrided functions
* (not relevant for this question)
*/
@Override
public void invokeDefaultOnBackPressed() {
super.onBackPressed();
}
@Override
protected void onPause() {
super.onPause();
if (mReactInstanceManager != null) {
mReactInstanceManager.onHostPause(this);
}
}
@Override
protected void onResume() {
super.onResume();
if (mReactInstanceManager != null) {
mReactInstanceManager.onHostResume(this, this);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
if (mReactInstanceManager != null) {
mReactInstanceManager.onHostDestroy(this);
}
}
@Override
public void onBackPressed() {
if (mReactInstanceManager != null) {
mReactInstanceManager.onBackPressed();
} else {
super.onBackPressed();
}
}
@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_MENU && mReactInstanceManager != null) {
mReactInstanceManager.showDevOptionsDialog();
return true;
}
return super.onKeyUp(keyCode, event);
}
}
Then, you can start your ReactActivity like this :
Intent intent = new Intent(getApplicationContext(), MyReactActivity.class);
startActivityForResult(intent, 123);
Get the result like this :
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == 123 && resultCode == Activity.RESULT_OK) {
float result = data.getExtras().getFloat("result");
// Do whatever you want with "result"
}
}
And just use it in React :
import { NativeModules } from 'react-native';
// [...]
// Call the function
NativeModules.TestModule.closewithresult(654.532);