com.facebook.react.bridge

Class BaseJavaModule

java.lang.Object

com.facebook.react.bridge.BaseJavaModule

All Implemented Interfaces:

NativeModule

Direct Known Subclasses:

AndroidInfoModule, ExceptionsManagerModule, ReactContextBaseJavaModule, SourceCodeModule, ViewManager

public abstract class BaseJavaModule
extends java.lang.Object
implements NativeModule

Base class for Catalyst native modules whose implementations are written in Java. Default implementations for initialize() and onCatalystInstanceDestroy() are provided for convenience. Subclasses which override these don't need to call super in case of overriding those methods as implementation of those methods is empty. BaseJavaModules can be linked to Fragments' lifecycle events, CatalystInstance creation and destruction, by being called on the appropriate method when a life cycle event occurs. Native methods can be exposed to JS with ReactMethod annotation. Those methods may only use limited number of types for their arguments: 1/ primitives (boolean, int, float, double 2/ String mapped from JS string 3/ ReadableArray mapped from JS Array 4/ ReadableMap mapped from JS Object 5/ Callback mapped from js function and can be used only as a last parameter or in the case when it express success & error callback pair as two last arguments respecively. All methods exposed as native to JS with ReactMethod annotation must return void. Please note that it is not allowed to have multiple methods annotated with ReactMethod with the same name.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	BaseJavaModule.JavaMethod

Nested classes/interfaces inherited from interface com.facebook.react.bridge.NativeModule

NativeModule.NativeMethod

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.String	METHOD_TYPE_ASYNC
static java.lang.String	METHOD_TYPE_PROMISE
static java.lang.String	METHOD_TYPE_SYNC

Constructor Summary

Constructors

Constructor and Description
BaseJavaModule()

Method Summary

Modifier and Type	Method and Description
boolean	canOverrideExistingModule() Return true if you intend to override some other native module that was registered e.g.
java.util.Map<java.lang.String,java.lang.Object>	getConstants()
java.util.Map<java.lang.String,NativeModule.NativeMethod>	getMethods()
void	initialize() This is called at the end of CatalystApplicationFragment#createCatalystInstance() after the CatalystInstance has been created, in order to initialize NativeModules that require the CatalystInstance or JS modules.
void	onCatalystInstanceDestroy() Called before {CatalystInstance#onHostDestroy}
boolean	supportsWebWorkers() In order to support web workers, a module must be aware that it can be invoked from multiple different JS VMs.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.facebook.react.bridge.NativeModule

getName

Field Detail

METHOD_TYPE_ASYNC

public static final java.lang.String METHOD_TYPE_ASYNC

See Also:

Constant Field Values

METHOD_TYPE_PROMISE

public static final java.lang.String METHOD_TYPE_PROMISE

See Also:

Constant Field Values

METHOD_TYPE_SYNC

public static final java.lang.String METHOD_TYPE_SYNC

See Also:

Constant Field Values

Constructor Detail

BaseJavaModule

public BaseJavaModule()

Method Detail

getMethods

public final java.util.Map<java.lang.String,NativeModule.NativeMethod> getMethods()

Specified by:

getMethods in interface NativeModule

Returns:

methods callable from JS on this module

getConstants

@Nullable
public java.util.Map<java.lang.String,java.lang.Object> getConstants()

Returns:

a map of constants this module exports to JS. Supports JSON types.

initialize

public void initialize()

Description copied from interface: NativeModule

This is called at the end of CatalystApplicationFragment#createCatalystInstance() after the CatalystInstance has been created, in order to initialize NativeModules that require the CatalystInstance or JS modules.

Specified by:

initialize in interface NativeModule

canOverrideExistingModule

public boolean canOverrideExistingModule()

Description copied from interface: NativeModule

Return true if you intend to override some other native module that was registered e.g. as part of a different package (such as the core one). Trying to override without returning true from this method is considered an error and will throw an exception during initialization. By default all modules return false.

Specified by:

canOverrideExistingModule in interface NativeModule

onCatalystInstanceDestroy

public void onCatalystInstanceDestroy()

Description copied from interface: NativeModule

Called before {CatalystInstance#onHostDestroy}

Specified by:

onCatalystInstanceDestroy in interface NativeModule

supportsWebWorkers

public boolean supportsWebWorkers()

Description copied from interface: NativeModule

In order to support web workers, a module must be aware that it can be invoked from multiple different JS VMs. Supporting web workers means recognizing things like: 1) ids (e.g. timer ids, request ids, etc.) may only unique on a per-VM basis 2) the module needs to make sure to enqueue callbacks and JS module calls to the correct VM In order to facilitate this, modules that support web workers will have all their @ReactMethod- annotated methods passed a ExecutorToken as the first parameter before any arguments from JS. This ExecutorToken internally maps to a specific JS VM and can be used by the framework to route calls appropriately. In order to make JS module calls correctly, start using the version of ReactContext.getJSModule(ExecutorToken, Class) that takes an ExecutorToken. It will ensure that any calls you dispatch to the returned object will go to the right VM. For Callbacks, you don't have to do anything special -- the framework automatically tags them with the correct ExecutorToken when the are created. Note: even though calls can come from multiple JS VMs on multiple threads, calls to this module will still only occur on a single thread.

Specified by:

supportsWebWorkers in interface NativeModule

Returns:

whether this module supports web workers.