chaxiu

fun getUserInfo(completion: Continuation<Any?>): Any?{}
fun getFriendList(user: String, completion: Continuation<Any?>): Any?{}
fun getFeedList(friendList: String, completion: Continuation<Any?>): Any?{}

chaxiu

fun testCoroutine(completion: Continuation<Any?>): Any? {}

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suspend fun testCoroutine() {
    log("start")
    val user = getUserInfo()
    log(user)
    val friendList = getFriendList(user)
    log(friendList)
    val feedList = getFeedList(friendList)
    log(feedList)
}

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// suspend modifier
// ↓
suspend fun noSuspendFriendList(user: String): String{
    // body is just like normal function
    return "Tom, Jack"
}

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suspend fun getUserInfo(): String {
    withContext(Dispatchers.IO) {
        delay(1000L)
    }
    return "BoyCoder"
}

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interface CallBack {
    void onSuccess(String response);
}

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public interface Continuation<in T> {
    public val context: CoroutineContext
//   just like: onSuccess(result)
//                 ↓         ↓
    public fun resumeWith(result: Result<T>)
}

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//                          Continuation is nothing but CallBack
//                                         ↓         
public static final Object getUserInfo(Continuation $completion) {
  ...
  return "BoyCoder";
}

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suspend fun getUserInfo(): String {
    withContext(Dispatchers.IO) {
        delay(1000L)
    }
    return "BoyCoder"
}

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// delay(1000L) representing request to server

//Suspending Function
// ↓
suspend fun getUserInfo(): String {
    withContext(Dispatchers.IO) {
        delay(1000L)
    }
    return "BoyCoder"
}