Question

在解雇@Database(entities = {PlaceSaved.class},version = 1) public abstract class PlaceDatabase extends RoomDatabase { private static PlaceDatabase INSTANCE; public static PlaceDatabase getDatabase(Context context){ if (INSTANCE == null){ INSTANCE = Room.databaseBuilder(context.getApplicationContext(), PlaceDatabase.class, "places_db").build(); } return INSTANCE; } public abstract DatabaseInterface PlacedatabaseInterface(); Intent活动时，我收到此错误

finish

此行导致错误

03-20 11:05:16.991 8566-8566/com.example.jenya1.ebilling E/AndroidRuntime: FATAL EXCEPTION: main
                                                                       Process: com.example.jenya1.ebilling, PID: 8566
                                                                       java.lang.ClassCastException: droidninja.filepicker.FilePickerDelegate cannot be cast to android.app.Activity
                                                                           at com.example.jenya1.ebilling.adapter.MaterialAdapter$1$1.onClick(MaterialAdapter.java:142)
                                                                           at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
                                                                           at android.os.Handler.dispatchMessage(Handler.java:105)
                                                                           at android.os.Looper.loop(Looper.java:164)
                                                                           at android.app.ActivityThread.main(ActivityThread.java:6541)
                                                                           at java.lang.reflect.Method.invoke(Native Method)
                                                                           at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                                                                           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)

调用apapter类

((Activity)mContext).finish();    //error

当用户点击提示对话框是按钮

时，我正在尝试

private void loadMaterialRequest() {

    final ProgressBar progressBar = (ProgressBar) findViewById(R.id.progressBar);
    //getting the progressbar

    //making the progressbar visible
    progressBar.setVisibility(View.VISIBLE);

    albumList.clear();

    //creating a string request to send request to the url
    StringRequest stringRequest = new StringRequest(Request.Method.GET, HttpUrl+token+"&type="+type,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    //hiding the progressbar after completion
                    progressBar.setVisibility(View.INVISIBLE);

                    try {
                        //getting the whole json object from the response
                        JSONObject obj = new JSONObject(response);

                        JSONArray heroArray = obj.getJSONArray("response");

                        //now looping through all the elements of the json array
                        for (int i = 0; i < heroArray.length(); i++) {
                            //getting the json object of the particular index inside the array
                            JSONObject heroObject = heroArray.getJSONObject(i);

                            //creating a hero object and giving them the values from json object
                            Material hero = new Material(
                                    heroObject.getInt("Request_id"),
                                    heroObject.getString("Site_name"),
                                    heroObject.getString("User_id"),
                                    heroObject.getString("Item_name"),
                                    heroObject.getString("Quantity"),
                                    heroObject.getString("Country"),
                                    heroObject.getString("Request_date"),
                                    heroObject.getString("Request_status"));

                            //adding the hero to herolist
                            albumList.add(hero);
                        }
                        //Log.e("list", String.valueOf(albumList));
                        //creating custom adapter object
                        adapter = new MaterialAdapter(getApplicationContext(),albumList);

                        //adding the adapter to listview
                        recyclerView.setAdapter(adapter);

                    } catch (JSONException e) {

                        e.printStackTrace();
                    }
                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                    Log.e("error", String.valueOf(error));

                }
            });

    //creating a request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //adding the string request to request queue
    requestQueue.add(stringRequest);
}

这是我的适配器类：

Intent

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Answer 1

让我们看看：

((Activity)mContext).finish();

日志说mContext是一种FilePickerDelegate。所以检查你的Adapter init函数。我认为你将上下文作为“this”传递，但是“this”引用了FilePickerDelegate。因此将其更改为YourActivity.this（带活动）或getActivity（带片段）

Answer 2

您正在传递应用程序上下文而不是适配器中的活动上下文。

getApplicationContext（）; 无论你在哪里传递它都会传递这个或ActivityName.this。

因为你试图将你传递的上下文（应用程序不是你想象的活动）转换为带有

的活动

（活动）你得到这个例外是因为你不能将应用程序转换为Activity，因为Application不是Activity的子类。

Answer 3

而不是Context使用适配器中的Activity。由于Activity可以转换为上下文，但上下文不能转换为活动。

Activity avtivity;

public MaterialAdapter(Activity activity, List<Material> albumList) {
this.activity = activity;
this.albumList = albumList;
}

初始化适配器时的调用活动如下所示调用此适配器。

new MaterialAdapter(<your calling activity>.this, yourList);

Answer 4

view.getContext().startActivity(new Intent(mContext, MaterialHistoryActivity.class));

无法在适配器中使用intent

4 个答案: