java.lang.IllegalStateException：片段不附着到活动 [英] java.lang.IllegalStateException: Fragment not attached to Activity

问题描述

我很少收到此错误，同时使一个API调用。

  java.lang.IllegalStateException：片段未连接到活动
 

我试图把code里面的 isAdded（）的方法来检查片段是否正在增加它的活动，但我依然很少得到这个错误。我不明白，为什么我仍然收到此错误。我怎么能prevent呢？

它的上线示值误差 -

  cameraInfo.setId（getResources（）的getString（R.string.camera_id）。）;
 

下面是我在做样本API调用。

  SAPI.getInfo（getActivity（）
                新APIResponseListener（）{
                    @覆盖
                    公共无效onResponse（对象响应）{


                        cameraInfo =新SInfo（）;
                        如果（isAdded（））{
                            cameraInfo.setId（getResources（）的getString（R.string.camera_id））;
                            cameraInfo.setName（getResources（）的getString（R.string.camera_name））;
                            cameraInfo.setColor（getResources（）的getString（R.string.camera_color））;
                            cameraInfo.setEnabled（真正的）;
                        }


                    }

                    @覆盖
                    公共无效onerror的（VolleyError错误）{
                        mProgressDialog.setVisibility（View.GONE）;
                        如果（错误的instanceof NoConnectionError）{
                            。字符串ERRORMSG = getResources（）的getString（R.string.no_internet_error_msg）;
                            Toast.makeText（getActivity（），ERRORMSG，Toast.LENGTH_LONG）.show（）;
                        }
                    }
                }）;
 

解决方案

此错误发生是由于两个因素的共同作用：

• 在HTTP请求，完成时，将调用无论是 onResponse（）或的onError（）（它的工作主线程），而无需知道活动是否仍然在前台与否。如果活动消失（用户在其他地方导航）， getActivity（）返回null。
• 凌空响应是pssed作为一个匿名内部类，其中隐含持有强引用外活动EX $ P $ 类。这将导致一个经典的内存泄漏。

要解决这个问题，你应该总是做的：

 活动活动= getActivity（）;
如果（活动！= NULL）{

    // 等等 ...

}
 

和也，使用 isAdded（）在的onError（）的方法，以及：

  @覆盖
公共无效onerror的（VolleyError错误）{

    活性活性= getActivity（）;
    如果（活动= NULL和放大器;！＆安培; isAdded（））
        mProgressDialog.setVisibility（View.GONE）;
        如果（错误的instanceof NoConnectionError）{
           。字符串ERRORMSG = getResources（）的getString（R.string.no_internet_error_msg）;
           Toast.makeText（活性，ERRORMSG，Toast.LENGTH_LONG）.show（）;
        }
    }
}
 

I am rarely getting this error while making an API call.

java.lang.IllegalStateException: Fragment  not attached to Activity

I tried putting the code inside isAdded() method to check whether fragment is currently added to its activity but still i rarely gets this error. I fail to understand why I am still getting this error. How can i prevent it?

Its showing error on the line-

cameraInfo.setId(getResources().getString(R.string.camera_id));

Below is the sample api call that i am making.

SAPI.getInfo(getActivity(),
                new APIResponseListener() {
                    @Override
                    public void onResponse(Object response) {


                        cameraInfo = new SInfo();
                        if(isAdded()) {
                            cameraInfo.setId(getResources().getString(R.string.camera_id));
                            cameraInfo.setName(getResources().getString(R.string.camera_name));
                            cameraInfo.setColor(getResources().getString(R.string.camera_color));
                            cameraInfo.setEnabled(true);
                        }


                    }

                    @Override
                    public void onError(VolleyError error) {
                        mProgressDialog.setVisibility(View.GONE);
                        if (error instanceof NoConnectionError) {
                            String errormsg = getResources().getString(R.string.no_internet_error_msg);
                            Toast.makeText(getActivity(), errormsg, Toast.LENGTH_LONG).show();
                        }
                    }
                });

解决方案

This error happens due to the combined effect of two factors:

• The HTTP request, when complete, invokes either onResponse() or onError() (which work on the main thread) without knowing whether the Activity is still in the foreground or not. If the Activity is gone (the user navigated elsewhere), getActivity() returns null.
• The Volley Response is expressed as an anonymous inner class, which implicitly holds a strong reference to the outer Activity class. This results in a classic memory leak.

To solve this problem, you should always do:

Activity activity = getActivity();
if(activity != null){

    // etc ...

}

and also, use isAdded() in the onError() method as well:

@Override
public void onError(VolleyError error) {

    Activity activity = getActivity(); 
    if(activity != null && isAdded())
        mProgressDialog.setVisibility(View.GONE);
        if (error instanceof NoConnectionError) {
           String errormsg = getResources().getString(R.string.no_internet_error_msg);
           Toast.makeText(activity, errormsg, Toast.LENGTH_LONG).show();
        }
    }
}

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