java - Activity再次执行时如何刷新静态值

Question

这里有一个名为groupchat的 Activity 。这里我有static对象activeEventMO。

In this groupchat activity the chatting function is going on. If user1 send a message to user2 that message received by gcmIntent class. in this gcmIntent class I have added the code for notification. Here if user1 send a message for a particular event notification received for user2. If user2 clicks that notification it will take to the user to that chat window that means groupchat activity.

为此，在 gcmIntent 类中，我使用 Parcelable 将 eventMO 发送到群聊 Activity 。如果 user1 向 user2 发送事件 2 的消息，则 user2 会收到通知。如果用户2点击通知，它会显示事件1的聊天窗口。因为当我第一次通过 sing eventMO 发送 eventid1 时。所以它永远保存eventid1。无法刷新。

这是我的群聊 Activity 代码

public class GroupChatActivity extends Activity {  
    private static ListView listViewMessages;
    private static List<ChatMO> listChatMessageObjectses = new ArrayList<ChatMO>();
    private static MessagesListAdapter adapter;
    private static Handler UIHandler;
    private static int RESULT_LOAD_IMAGE = 1;
    private EditText inputMsg;
    private String formatDate;
    private Context context;
    private String dateResult;
    private static EventMO activeEventMO = null;
    private UserDelegate userDelegate = new UserDelegate();
    private MediaDelegates mediaDelegates = new MediaDelegates();
    private MessageDelegates messageDelegates = new MessageDelegates();
    private SharedPreferences sharedpreferences;
    private List<UserMO> eventUserMOs = new ArrayList<>();
    private Gson gson = new Gson();
    private UserMO userMO = new UserMO();
    private MessageMO messageMO = new MessageMO();
    private File imgFile;
    private MediaMO mediaMO = new MediaMO();

    // this method is for store the current event id to eventMO coz eventMO globally declared as static
   public  void getevent()
    {
        activeEventMO = (EventMO) getIntent().getParcelableExtra("eventMo");
    }

    public static void messageHandler(final MessageMO messageMo) {
        UIHandler = new Handler(Looper.getMainLooper());
        UIHandler.post(new Runnable() {
            public void run() {

                Log.e("messageHandler", messageMo.getEventTitle());
                ChatMO chatMO = new ChatMO();
                chatMO.setMessage(messageMo.getMessage());
                chatMO.setSelf(0);
                chatMO.setFromName(messageMo.getfromUserName());
                chatMO.setDate(messageMo.getDate());
                Log.e("handler", "eventMO" + activeEventMO);
                Log.e("handler", "messageMO" + messageMo);

                if (activeEventMO.getEventId() == messageMo.getEventId()) {
                    listChatMessageObjectses.add(chatMO);
                    listViewMessages.setAdapter(adapter);

                    adapter.notifyDataSetChanged();
               }
            }
        });
    }

    @Override
    protected void onStart() {
        super.onStart();
        SharedPreferences.Editor editor = sharedpreferences.edit();
        editor.putInt("APPSTATUS", 1);
        editor.putLong("eventId", activeEventMO.getEventId());
        editor.commit();
        Log.i("App", "start");
        AppActivityStatus.setActivityStarted();
        AppActivityStatus.setActivityContext(context);
    }

    @Override
    protected void onPause() {
        super.onPause();
        AppActivityStatus.setActivityStoped();
    }

    @Override
    protected void onResume() {
        super.onPause();
        AppActivityStatus.setActivityStarted();
    }

    @Override
    protected void onStop() {
        super.onStop();
        Log.i("App", "stop");
        SharedPreferences.Editor editor = sharedpreferences.edit();
        editor.putInt("APPSTATUS", 2);
        editor.commit();
        AppActivityStatus.setActivityStoped();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.image_upload, menu);
        return true;
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data) {
            Uri selectedImage = data.getData();
            String[] filePathColumn = {MediaStore.Images.Media.DATA};
            Cursor cursor = getContentResolver().query(selectedImage,
                    filePathColumn, null, null, null);
            cursor.moveToFirst();

            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
            String picturePath = cursor.getString(columnIndex);
            cursor.close();
            ChatMO chatMO = new ChatMO();
            chatMO.setMessage_type(Constants.IS_TYPE_CHAT_IMAGE);
            chatMO.setMessage(picturePath);
            chatMO.setSelf(1);
            chatMO.setIs_delete(0);
            chatMO.setFromName("");
            chatMO.setEvent_id(activeEventMO.getEventId());
            messageMO.setMessage("");
            messageMO.setRingeeUserId(userMO.getRingeeUserId());
            // messageMO.setDate(messageMO.getDate());
            messageMO.setMobileNumber(userMO.getMobileNumber());
            messageMO.setEventId(activeEventMO.getEventId());
            messageMO.setEventTitle(activeEventMO.getText());
            Log.e("sendbutton", "eventtitle" + messageMO.getEventTitle());
            messageMO.setfromUserName(userMO.getUserName());
            messageMO.setMessageType(Constants.MESSAGE_TYPE_MSG);
            mediaMO.setRingeeUserId(userMO.getRingeeUserId());
            mediaMO.setIsType(Constants.IS_TYPE_CHAT_IMAGE);
            imgFile = new File(picturePath);
            listChatMessageObjectses.add(chatMO);
            listViewMessages.setAdapter(adapter);
            adapter.notifyDataSetChanged();
            new AsyncTask<Void, Void, String>() {
                @Override
                protected String doInBackground(Void... arg0) {
                    return mediaDelegates.insertChatFile(context, imgFile, messageMO, eventUserMOs, mediaMO);
                }

                @Override
                protected void onPostExecute(String mediaBo) {
                    Toast.makeText(getApplicationContext(), "uploaded Status" + mediaBo, Toast.LENGTH_LONG).show();
                    if (!mediaBo.equals("null")) {
                        MediaMO mediaMO1 = gson.fromJson(mediaBo, new TypeToken<MediaMO>() {
                        }.getType());

                    }
                }
            }.execute(null, null, null);
        }
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();
        // noinspection SimplifiableIfStatement

        if (id == R.id.ic_menu_gallery) {

            Intent i = new Intent(
                    Intent.ACTION_PICK,
                    android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
            startActivityForResult(i, RESULT_LOAD_IMAGE);
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        final List<ChatMO> chatMOs1 = new ArrayList<>();
        activeEventMO = new EventMO();
        setContentView(R.layout.chat_main);
        context = getApplicationContext();
        String message = "";
        DatabaseHelper dbHelper = new DatabaseHelper(context);
        listChatMessageObjectses = chatMOs1;
        inputMsg = (EditText) findViewById(R.id.inputMsg);
        listViewMessages = (ListView) findViewById(R.id.list_view_messages);
        activeEventMO = (EventMO) getIntent().getParcelableExtra("eventMo");
        Log.e("oncreate", "eventMO" +activeEventMO);
        List<ChatMO> chatMOs = dbHelper.getGroupChatMessageForEvent(activeEventMO.getEventId());
        Log.e("oncreate", "chatMOs" + chatMOs);
        for (ChatMO chatMO1 : chatMOs) {
            message = chatMO1.getMessage();
            chatMO1.getEvent_id();
            chatMO1.getFromName();
            int messageType = chatMO1.getMessage_type();
            chatMO1.getDate();
            chatMO1.isSelf();
            if (messageType == 0) {
                chatMOs1.add(chatMO1);
            }


        }

        adapter = new MessagesListAdapter(context, chatMOs1);
        //adapter functionality added for show the previous chat list of event/invite
        listViewMessages.setAdapter(adapter);
        sharedpreferences = getSharedPreferences(Constants.SHARED_PREFERENCE_NAME, context.MODE_PRIVATE);
        // by default first primary user is current user in sql lite
        // user table
        userMO = dbHelper.getUserData(1);

这里我在 gcmIntent 中传递 eventMO

Intent groupChatActFrag = new Intent(getApplicationContext(), GroupChatActivity.class);
            EventMO eventMO = new EventMO();
            eventMO.setEventId(messageMO.getEventId());
            Log.e("gcm","evetid"+eventMO.getEventId());
            groupChatActFrag.putExtra("eventMo", eventMO);
            groupChatActFrag.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
            SharedPreferences.Editor editor = sharedpreferences.edit();
            editor.putString("MessageMO", gson.toJson(messageMO));
            editor.commit();
            PendingIntent contentIntent = PendingIntent.getActivity(this, 0, groupChatActFrag, 0);

            NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this).setSmallIcon(R.drawable.ic_dialog_info).setContentTitle(messageMO.getEventTitle())
                    .setStyle(new NotificationCompat.BigTextStyle().bigText(messageMO.getfromUserName())).setContentText(messageMO.getMessage()).setSound(RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION));

            mBuilder.setContentIntent(contentIntent);

            mBuilder.setAutoCancel(true);
            Log.e("gcm","eventid"+messageMO.getEventId());

            mNotificationManager.notify((int) (long) eventMO.getEventId(), mBuilder.build());

        }

您能告诉我如何解决这个问题吗？提前致谢

Answer 1

要在 Activity 或 fragment 被销毁后刷新变量，您需要将其存储在方法中提供的已保存 bundle 中


公共(public)无效 onSavedInstanceState(最终 bundle )


并使用方法中提供的 bundle 重置值


公共(public)无效onCreate(最终 bundle 保存实例)


这里有一些很好的文档

enter code here[Recreating an Activity - Android][1]