如何暂停AsyncTask询问用户详细信息?

问题描述

我想在AsyncTask的doInBackground()中做一些工作时向用户询问一些细节(向用户显示UI线程中具有选择的对话框)，并在用户选择后继续在doInBackground()中执行所选择的工作对话框中的参数.

I want to ask user for some details while doing some work in doInBackground() of AsyncTask (showing to user some dialog with choices in UI-thread), and after users choice continue the job in doInBackground() with chosen parameters from dialog.

将此参数传输到doInBackground()的最佳机制是什么?我应该如何暂停(并继续)执行doInBackground()的线程(也许是object.wait()和notify()?)?为此，我应该使用Handler吗?

What is a best mechanism of transfer this parameter to doInBackground()? How I should pause (and continue) thread doing doInBackground() (maybe object.wait() and notify()?)? Should I use a Handler for this purpose?

推荐答案

在实际启动后台任务之前，我会先询问用户输入.如果这不可能，则有以下几种可能性:

I would ask user for input before actually starting background task. If this is not possible there are couple possibilities:

1. 您可以使用锁对象并对其执行通常的wait()/notify()事情.不过，您仍然需要将数据从UI线程传递到后台线程

1. You can use lock object and do usual wait()/notify() stuff on it. You still need to pass data from UI thread to your background thread though

我将使用队列将数据从UI线程传递到后台线程，并让它处理所有锁定.

I would use queue to pass data from UI thread to background thread and let it handle all the locking.

类似这样的东西(伪代码)

Something like this (kind of pseudo-code)

class BackgroundTask extends AsyncTask<BlockingQueue<String>, ...> {
    void doInBackground(BlockingQueue<String> queue) {
      ...
      String userInput = queue.take(); // will block if queue is empty
      ...
    }
}

// Somewhere on UI thread:
   BlockingQueue<String> queue = new ArrayBlockingQueue<String>(1);
   BackgroundTask task = new BackgroundTask<BlockingQueue<String>,....>();
   task.execute(queue);
   ....
   ....
   String userInput = edit.getText().toString(); // reading user input
   queue.put(userInput); // sending it to background thread. If thread is blocked it will continue execution

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