Android从匿名类中获取活动 [英] Android get activity from within anonymous class

问题描述

我是Android开发和Java的新手。这是基本设置：我有一个带有 AsyncTask 的启动画面来检查服务器可用性。在这个主题之后，我在我的活动中进行了回调。这比在 OnPostExecute（）中完成工作更有意义，因为我想在不同的活动中重复使用此任务。

I'm super new to Android development and Java in general. Here's the basic setup: I have a splash screen with an AsyncTask to check server availability. Following this thread I made a callback in my activity. This makes more sense than doing the work in OnPostExecute() as I want to reuse this task in different activities.

但是，在我的回调中，我会检查状态是否正常。如果是，它应该启动下一个活动。但是从我的回调的上下文中，我不知道如何获得我的 Activity 引用，我需要它作为Intent的参数。

However, in my callback I do a check if the status is okay. If it is, it should launch the next activity. But from the context of my callback, I don't get how I can get my Activity reference, which I need as a parameter for the Intent.

这是OnCreate下我的活动中的代码：

This is the code in my Activity under OnCreate:

    //Check server status
    CheckServiceTask t = new CheckServiceTask(new OnTaskCompleted<ShaggyServiceStatus>() {
        @Override
        public void onTaskCompleted(ShaggyServiceStatus result) {
            Log.i(TAG, "Callback. Result: " + result.getStatus());
            ProgressBar pb = (ProgressBar) findViewById(R.id.splash_progress);
            pb.setVisibility(View.INVISIBLE);

            if (result.getStatusCode() == 999){
                TextView t = (TextView) findViewById(R.id.splash_status_text);
                t.setText(result.getStatus());
                return;
            }

            Intent i = new Intent(getActivity(), LoginActivity.class);
            startActivity(i);
            finish();

        }
    });

    t.execute();

失败的部分是 getActivity（）。那个电话不可用。使用这个会抛出一个错误（我理解，因为我在 OnTaskCompleted 的上下文中）。

The part where this fails is at getActivity(). That call is not available. Using this throws an error (which I understand, as I'm in the context of OnTaskCompleted).

为了完整性，这是OnTaskCompleted的接口：

For completeness, this is the interface for OnTaskCompleted:

public interface OnTaskCompleted<T> {
    public void onTaskCompleted(T result);
}

这是CheckServiceTask类：

And this is the CheckServiceTask class:

public class CheckServiceTask extends AsyncTask<Void, Void, ShaggyServiceStatus>{
    private static final String TAG = "coo";

    public OnTaskCompleted<ShaggyServiceStatus> listener;

    public CheckServiceTask (OnTaskCompleted<ShaggyServiceStatus> l){
        this.listener = l;
    }

    @Override
    protected ShaggyServiceStatus doInBackground(Void... params) {
        try {
            Log.i(TAG, "Connecting to server...");
            //TODO: Make this a setting
            final String url = "https://someplace.com/status";
            RestTemplate restTemplate = new RestTemplate();
            restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
            //restTemplate.postForObject("url", bodyObject, ShaggySer.class);
            ShaggyServiceStatus sss = restTemplate.getForObject(url, ShaggyServiceStatus.class);
            Log.d(TAG, "Got the status.");
            return sss;
        } catch (Exception e) {
            //TODO: Exception handling
            Log.e(TAG, e.getMessage(), e);
        }

        //If we're here, it's not okay.
        ShaggyServiceStatus r = new ShaggyServiceStatus("Cannot connect to server", 999, "none");

        return r;
    }

    @Override
    protected void onPostExecute(ShaggyServiceStatus result) {
        super.onPostExecute(result);
        listener.onTaskCompleted(result);
    }
}

推荐答案

使用 CurrentClassName.this

Intent i = new Intent(CurrentClassName.this, LoginActivity.class);

getActivity（）：与片段一起使用

返回此片段当前与之关联的活动。

Return the Activity this fragment is currently associated with.

$ b $当你有嵌套的类时，b

class.this 与这个不同。

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