将数据从Android Volley设置为变量

Question

我有一个Volley请求，我试图将结果设置在一个变量中，但是出现错误“从内部类访问变量'stuff'，需要声明为final”。 问题是，一旦我将其声明为final，就不允许将变量设置为等于响应（就像我在try块中尝试的那样）。 我四处寻找讨论该问题的其他问题，但没有一个问题对我的情况有所帮助。 这是代码：

public ArrayList getStuff() {
    ArrayList<JSONObject> stuff;
    new Thread(new Runnable() {
        @Override
        public void run() {
            // Instantiate the RequestQueue.
            RequestQueue queue =     MySingleton.getInstance(getApplicationContext()).getRequestQueue();
            String url ="http://localhost:6000/stuff";

            RequestFuture<String> future = RequestFuture.newFuture();
            // Testing out blocking
            StringRequest stringRequest = new StringRequest(Request.Method.GET, url, future, future);
            // Add the request to the RequestQueue.
            queue.add(stringRequest);

            try {
                String response = future.get(30, TimeUnit.SECONDS);
                stuff = response;
                Log.i("tutors after blocked: ", tutors);
            } catch(InterruptedException e) {
                e.printStackTrace();
            } catch(ExecutionException e) {
                e.printStackTrace();
            } catch (TimeoutException e) {
                e.printStackTrace();
            }
        }
    }).start();

    // I want to be able to return 'stuff' here
    return stuff;

}

Answer 1

只需添加final一词，如下所示。

public ArrayList getStuff() {
final ArrayList<JSONObject> stuff; <--Add final here
new Thread(new Runnable() {
    @Override
    public void run() {
        // Instantiate the RequestQueue.
        RequestQueue queue =     MySingleton.getInstance(getApplicationContext()).getRequestQueue();
        String url ="http://localhost:6000/stuff";

        RequestFuture<String> future = RequestFuture.newFuture();
        // Testing out blocking
        StringRequest stringRequest = new StringRequest(Request.Method.GET, url, future, future);
        // Add the request to the RequestQueue.
        queue.add(stringRequest);

        try {
            String response = future.get(30, TimeUnit.SECONDS);
            stuff = response;
            Log.i("tutors after blocked: ", tutors);
        } catch(InterruptedException e) {
            e.printStackTrace();
        } catch(ExecutionException e) {
            e.printStackTrace();
        } catch (TimeoutException e) {
            e.printStackTrace();
        }
    }
}).start();

// I want to be able to return 'stuff' here
return stuff;

}

Answer 2

只需将变量声明移到方法外即可。 这意味着它已经是该类的全局变量

ArrayList<JSONObject> stuff;

public ArrayList getStuff() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            // Instantiate the RequestQueue.
            RequestQueue queue =     MySingleton.getInstance(getApplicationContext()).getRequestQueue();
            String url ="http://localhost:6000/stuff";

            RequestFuture<String> future = RequestFuture.newFuture();
            // Testing out blocking
            StringRequest stringRequest = new StringRequest(Request.Method.GET, url, future, future);
            // Add the request to the RequestQueue.
            queue.add(stringRequest);

            try {
                String response = future.get(30, TimeUnit.SECONDS);
                stuff = response;
                Log.i("tutors after blocked: ", tutors);
            } catch(InterruptedException e) {
                e.printStackTrace();
            } catch(ExecutionException e) {
                e.printStackTrace();
            } catch (TimeoutException e) {
                e.printStackTrace();
            }
        }
    }).start();

    // I want to be able to return 'stuff' here
    return stuff;

}

Answer 3

深入研究之后，我想到了SharedPreferences ，

如果您确实需要外部响应数据，则可以使用SharedPreferences将响应值存储在某个变量中，并在需要时在外部读取相同的值。

为变量设置值

String MyPREFERENCES = "MyPrefs";
SharedPreferences.Editor editor = context.getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE).edit();
editor.putString("returnResponse", "success");
editor.apply();

获取变量的值

String return_value = sharedpreferences.getString("returnResponse", "");