需要帮助将 Kotlin 转换为 Java

Question

我对 Kotlin 的了解为零，我知道 Kotlin 可能是未来，但我有项目需要用 Java 完成，我看过这篇不错的帖子：here 但它是在 Kotlin 中完成的，并且我很难将其更改为 Java，尤其是 (T.() -> Unit)? 语法...

那么，任何人都可以帮助我将下面的 2 转换为 Java 吗？

class LiveMessageEvent<T> : SingleLiveEvent<(T.() -> Unit)?>() {
    fun setEventReceiver(owner: LifecycleOwner, receiver: T) {
        observe(owner, Observer { event ->
            if ( event != null ) {
                receiver.event()
            }
        })
    }

    fun sendEvent(event: (T.() -> Unit)?) {
        value = event
    }
}

还有这段代码：

const val GOOGLE_SIGN_IN : Int = 9001

class LoginViewModel @Inject constructor(
    private val loginRepository: LoginRepository,
    private val googleSignInClient: GoogleSignInClient
): ViewModel() {

    val startActivityForResultEvent = LiveMessageEvent<ActivityNavigation>()
    ..

    //Called on google login button click
    fun googleSignUp() {
        val signInIntent = googleSignInClient.signInIntent
        startActivityForResultEvent.sendEvent { 
startActivityForResult(signInIntent, GOOGLE_SIGN_IN) }
    }

//Called from Activity receving result
fun onResultFromActivity(requestCode: Int, resultCode: Int, data: Intent?) {
    when(requestCode) {
        GOOGLE_SIGN_IN -> {
            val task = GoogleSignIn.getSignedInAccountFromIntent(data)
            googleSignInComplete(task)
        }
        ..
    }
}

private fun googleSignInComplete(completedTask: Task<GoogleSignInAccount>) {
    try {
        val account = completedTask.getResult(ApiException::class.java)
        account?.apply {
            // .. Store user details
            emitUiState(
                showSuccess = Event(R.string.login_successful)
            )
        }
    }catch (e: ApiException) {
        emitUiState(
            showError = Event(R.string.login_failed)
        )
    }
}

感谢您的帮助...

编辑：

我确实尝试从 Android Studio 反编译，这是我得到的：

public final class LiveMessageEvent extends SingleLiveEvent {
   public final void setEventReceiver(@NotNull LifecycleOwner owner, final Object receiver) {
      Intrinsics.checkParameterIsNotNull(owner, "owner");
      this.observe(owner, (Observer)(new Observer() {
         // $FF: synthetic method
         // $FF: bridge method
         public void onChanged(Object var1) {
            this.onChanged((Function1)var1);
         }

         public final void onChanged(@Nullable Function1 event) {
            if (event != null) {
               event.invoke(receiver);
            }

         }
      }));
   }

   public final void sendEvent(@Nullable Function1 event) {
      this.setValue(event);
   }
}

从上面的结果中我不太确定Intrinsics、function1、invoke 和object 是什么...

Answer 1

您只需执行以下操作即可从 kotlin 获取 java 代码：

1. 菜单 > 工具 > Kotlin > 显示 Kotlin 字节码
2. 点击反编译按钮
3. 复制java代码

使用最新版本 (1.2+) 的 Kotlin 插件，您还可以直接执行菜单 > 工具 > Kotlin -> 将 Kotlin 反编译为 Java。