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将Java Lambda转换为Kotlin Lamba时出错

kotlin lambda android

Hello World · 技术社区 · 7 年前

我想用Fetch2在我的应用程序中下载一个文件,但是我在尝试时遇到了这个错误。

    fetch.enqueue(request, updatedRequest -> {
        //Request was successfully enqueued for download.
    }, error -> {
        //An error occurred enqueuing the request.
    });

    fetch.enqueue(request,
    success = { _: com.tonyodev.fetch2.Request ->
        TODO()        
    },
    failed = {  _: com.tonyodev.fetch2.Error ->
        TODO()
    })

这是我得到的错误:

编辑: 我在编译代码时遇到了这个错误。

None of the following functions can be called with the arguments supplied:
public abstract fun enqueue(request: Request, func: Func<Request>? = ..., func2: Func<Error>? = ...): Fetch defined in com.tonyodev.fetch2.Fetch
public abstract fun enqueue(requests: List<Request>, func: Func<List<Request>>? = ..., func2: Func<Error>? = ...): Fetch defined in com.tonyodev.fetch2.Fetch

4 回复 | 直到 7 年前

GianhTran 7 年前

试试看

  fetch.enqueue(request,
    success = { 
        TODO()        
    },
    failed = { 
        TODO()
    })

Vladimir Gladun 7 年前

您检查过您在这里尝试使用的方法中的签名和javadoc吗?

/**
     * Queues a request for downloading. If Fetch fails to enqueue the request,
     * func2 will be called with the error.
     * Errors that may cause Fetch to fail the enqueue are :
     * 1. No storage space on the device.
     * 2. Fetch is already managing the same request. This means that a request with the same url
     * and file name is already managed.
     * @param request Download Request
     * @param func Callback that the enqueued request will be returned on.
     *             Fetch may update a request depending on the initial request's Enqueue Action.
     *             Update old request references with this request.
     * @param func2 Callback that is called when enqueuing a request fails. An error is returned.
     * @throws FetchException if this instance of Fetch has been closed.
     * @return Instance
     * */
    fun enqueue(request: Request, func: Func<Request>? = null, func2: Func<Error>? = null): Fetch

/**
 * Queues a list of requests for downloading. If Fetch fails to enqueue a
 * download request because an error occurred, all other request in the list will
 * fail. Func2 will be called with the error message.
 * Errors that may cause Fetch to fail the enqueue are :
 * 1. No storage space on the device.
 * 2. Fetch is already managing the same request. This means that a request with the same url
 * and file name is already managed.
 * @param requests Request List
 * @param func Callback that the enqueued request will be returned on.
 *             Fetch may update a request depending on the initial request's Enqueue Action.
 *             Update old request references with this request.
 * @param func2 Callback that is called when enqueuing a request fails. An error is returned.
 * @throws FetchException if this instance of Fetch has been closed.
 * @return Instance
 * */
fun enqueue(requests: List<Request>, func: Func<List<Request>>? = null, func2: Func<Error>? = null): Fetch

所以第二个和第三个参数基本上是回调,你甚至可以跳过或调用类似的fetch.排队(request,object:Func{//在此处实现回调方法

SaurabhS 7 年前

目前,在将javasam转换为kotlinlambdas时,必须显式地指定类型。因此,您的代码应该类似于:

fetch.enqueue(request,
    success = Func<Request> { _: com.tonyodev.fetch2.Request ->
        TODO()        
    },
    failed = Func<Error> {  _: com.tonyodev.fetch2.Error ->
        TODO()
    })

tryp 7 年前

fetch.enqueue(request, Func {
    // success
}, Func {
   // failure
})

Hello World 7 年前

我现在可以解决我的问题,即使我不知道它是如何工作的。

    fetch.enqueue(request)
        Func<Request> { _ ->
            //TODO()
        }
        Func<com.tonyodev.fetch2.Error> { _ ->
            //TODO()

    fetch.enqueue(request,
        Func { _ ->
            //TODO()
        },
        Func { _ ->
            //TODO()
        })