You're declaring an interface with the methods you need to do in the field. Activity:interface FragmentActions { void doSomething(); } Implement the interface in Activity:class MainActivity extend Activity implement FragmentActions { override void doSomething(){ ... Вызываешь свои методы реализованные в активности } } You call a method in a fragment:class MainFragment extend Fragment { private FragmentActions listener; override void onAttach(Context context){ super.onAttach(context) listener = (FragmentActions)context; } override void onViewCreated(...){ btn.setOnClickListener(()->listener.doSomething()) } }

Judging by the google, it's all bad with this permission. A bunch of bagovs and a normal solution for the moment. You can only try to put a flag in the activists before the start of the line, which they are being requested now and at the next call. onResume() I'll check it again. If it is, it's all right, or it's canceled.

In short, I've been riding with it all. He fixed his mistakes in the classroom. In principle, the desired result was: SplashActivity hanging right before the opening of the next Activity♪public class SplashActivity extends AppCompatActivity { private DatabaseReference databaseReference; private ValueEventListener valueEventListener; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); tryToConnect(); } @Override protected void onResume() { super.onResume(); databaseReference.addValueEventListener(valueEventListener); } @Override protected void onStop() { super.onStop(); databaseReference.removeEventListener(valueEventListener); } @Override protected void onPause() { super.onPause(); databaseReference.removeEventListener(valueEventListener); } private void tryToConnect(){ SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this); if (preferences.getString("Login","").equals("") || preferences.getString("Password","").equals("")){ showSignInActivity(); } else { if (hasConnection()) { valueEventListener = new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot) { ArrayList<User> userList = Globals.Downloads.getVerifiedUserList(dataSnapshot); SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(SplashActivity.this); checkVerificationData(userList, preferences.getString("Login", ""), preferences.getString("Password", "")); } @Override public void onCancelled(DatabaseError databaseError) { Toast.makeText(getApplicationContext(), "Ошибка в работе базы данных. Обратитесь к администратору компании или разработчику", Toast.LENGTH_LONG).show(); SplashActivity.this.finish(); } }; databaseReference = FirebaseDatabase.getInstance().getReference(); } else { Toast.makeText(getApplicationContext(), "Нет подключения к интернету", Toast.LENGTH_LONG).show(); showSignInActivity(); } } } private void showSignInActivity(){ startActivity(new Intent(SplashActivity.this, SignInActivity.class)); SplashActivity.this.finish(); } private void signIn(User user){ Toast.makeText(getApplicationContext(), "Вход выполнен", Toast.LENGTH_LONG).show(); if (PreferenceManager.getDefaultSharedPreferences(this).getBoolean("allowNotifications", false)) startService(new Intent(this, MessagingService.class)); Globals.currentUser = user; startActivity(new Intent(SplashActivity.this, AcceptedTicketsActivity.class)); SplashActivity.this.finish(); } private void checkVerificationData(ArrayList<User> userList, String login, String password) { int i = 0; while (!login.equals(userList.get(i).getLogin()) && ++i < userList.size()); if (i >= userList.size()) { Toast.makeText(getApplicationContext(), "Логин и/или пароль введен неверно. Повторите попытку", Toast.LENGTH_LONG).show(); showSignInActivity(); } else if (login.equals(userList.get(i).getLogin()) && password.equals(userList.get(i).getPassword())) signIn(userList.get(i)); else { Toast.makeText(getApplicationContext(), "Логин и/или пароль введен неверно. Повторите попытку", Toast.LENGTH_LONG).show(); showSignInActivity(); } } private boolean hasConnection() { ConnectivityManager cm = (ConnectivityManager)SplashActivity.this.getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo activeNetwork = cm.getActiveNetworkInfo(); return activeNetwork.isConnectedOrConnecting(); } } Steel changed it.<style name="AppTheme.Launcher" parent="AppTheme.NoActionBar"> <item name="android:windowBackground">@drawable/background_splash</item> </style> <style name="AppTheme.NoActionBar" parent="AppTheme"> <item name="windowActionBar">false</item> <item name="windowNoTitle">true</item> </style>

In general, events onResume can be signed and resigned onPause - onPause will be called upon to leave the activate (not importantly, what kind of care is the transition to the next activism, the return to the previous, the rolling of the annex), onResume, when the oath is activated.But you have to be careful, onPause will be called in at the opening of the dialogues.

You can add a parameter in the manifest. android:launchMode♪ There are four options, but you need to. singleInstance♪ Maybe. singleTask♪ Works like this: if there's no instas of activism, a new one is being created, and if there is, this activism is just pushing up.There's a nuance with data from the intent. This is the method. onNewIntent in which a new intent will, which has triggered a current copy of the activate. Details can be read https://developer.android.com/guide/topics/manifest/activity-element.html#lmode

Class MainActivity should be in the file. MainActivity.java♪ You have a name. Main_acseller♪

If MainActivity It's not a big deal, it's probably the point that if you want to call her, you're pointing out the wrong thing. action Ooh. intent♪ Indicate the manifest or use a clear intent. I mean, try it. SplashActivity replace startActivity(new Intent("com.tutorial.activity_main")); ♪ startActivity(new Intent("com.example.summer.activity_main")); or startActivity(new Intent(this, MainActivity.class));The latter matches a clear instinct.

RecyclerView Not only does it involve initializing the adapter, but also classes. ViewHolder, you may use them and determine which activities should be opened according to the class representing the visual, such as: /** * Выбирает нужный тип визуалки * * @param position - позиция элемента * @return int - тип визуалки */ @Override public int getItemViewType(int position) { //в данном случае элементы списка отличаются классом, можно определять и по другим параметрам объекта, как вам удобнее Object item = mItems.get(position); if (item instanceof Message) { return 0; } else if (item instanceof TalkItems.TalkDate) { return 1; } return -1; } /** * Выбирает нужную визуалку по её типу * * @param parent - родительская визуалка * @param viewType - тип визуалки * @return ViewHolder|null визуалка */ @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { LayoutInflater inflater = LayoutInflater.from(TalkActivity.this); switch (viewType) { case 0: return new MessageView( inflater.inflate(R.layout.talk_message_my, parent, false) ); case 1: return new DateView( inflater.inflate(R.layout.talk_date, parent, false) ); default: if (BuildConfig.DEBUG) { throw new AssertionError("Неизвестный тип визуалки"); } return null; } } private class MessageView extends RecyclerView.ViewHolder { MessageView(View itemView) { super(itemView); final Context context = getApplicationContext(); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { context.startActivity(new Intent(context, MainActivity.class)); } }); } } private class DateView extends RecyclerView.ViewHolder { DateView(View itemView) { super(itemView); final Context context = getApplicationContext(); itemView.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { context.startActivity(new Intent(context, ThirdActivity.class)); } }); } } If your elements of the list have the same visual, but different content, you can use the following method:/** * В данном примере используем один класс MessageView, новый класс ниже * Заполнение визуальной составляющей элемента * * @param holder - пустая визуалка * @param position - позиция элемента */ @Override public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { if (holder == null) { return; } Object item = mItems.get(position); final Context context = getApplicationContext(); MessageView mesHolder = (MessageView) holder; if (item instanceof Message) { mesHolder.view.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { context.startActivity(new Intent(context, MainActivity.class)); } }); } else if (item instanceof DateItem) { mesHolder.view.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { context.startActivity(new Intent(context, ThirdActivity.class)); } }); } } private class MessageView extends RecyclerView.ViewHolder { public View view; MessageView(View itemView) { super(itemView); view = itemView; } }

Problem is, class:public class Alert { public String alert_head; public String alert_date; public Alert(String alert_head, String alert_date) { this.alert_head = alert_head; this.alert_date = alert_date; } is not in any way activity♪For him to become activitymust be inherited from the class concerned, e.g. from AppCompatActivity and implement appropriate methods, onCreate(...)♪Maybe in the line:Intent intent3 = new Intent(getApplication(), Alert.class); You wanted to go instead. Alert.class write something else.

Every time a new instance activity was created on the UP button without parameters, which triggered NPE to open the activity in the state that it was, in the manifest, it needs to describe the atribut. android:launchMode="singleTop"

It's not clear from the description what the problem is. ♪ ♪ But you can try this:recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));

Exception java.lang.NoSuchMethodError It says,such a method&quot; and generated when you cannot find the method you cause.Use ActionBar low API possiblein particular(d) Library AppCompat and its class AppCompatActivity (in which case) getActionBar() Method getSupportActionBar() with similar appointment.To solve this problem, you may inherit Activity_setting from AppCompatActivity:public class Activity_setting extends AppCompatActivity { ... } and replace the method getActionBar() ♪ getSupportActionBar()♪

Because the methods you listed are being summoned after challenge onCreate(...)♪

At each point of time, there's only one activism that's visible on the screen. All others in the background (or at all destroyed) and the code in any case is not met (Android 7 introduced a multi-consistency regime, but it also carries a code only of visible activities on the screen).You can write your own class-- click-teacher. https://ru.stackoverflow.com/a/259662/177345 OnClickListener(d) and include it in different activities, but in practice such an approach is usually difficult to implement and carries more crutches than profiling.Two-seat buttons (interface and separate panels) use fragments - it is possible to use a separate class-teacher for a realistic interface. OnClickListener and managing the knobs.In fact, the player is about to be realized: music is losing. Service♪ There is also a fragment with the loser management interface that interacts with the service and manages reproduction. This fragment is now being removed wherever the control panel is required. If necessary, the data exchange with the outside world is created by the collars.If you need a reaction to the user's actions in another activist, you create your own interface there and you take your own listeners. If necessary, transmit the parameters (e.g., lost track number), flight https://ru.stackoverflow.com/a/556943/177345 Through https://ru.stackoverflow.com/a/293280/177345 or library, https://ru.stackoverflow.com/a/470923/177345 ♪ For feedback https://ru.stackoverflow.com/a/136267/177345 If you thought about the need for action on your question, you first built the incorrect architecture of your application and secondly, lacked knowledge to develop under this platform. I'm recommending the books, Brian Hardy, Reto Meyer and Paul Datell, then write an app.PS: Transfer copies of whatever might be the worst, I recommend not even think about it.

In the standard situation, it is sufficient to cause finish() - the activists will be over. The case described below should be used only in extreme situations. In the world of the Android, it's not accepted manually to complete the processes, all of which has to do the system in its own sense.//эмулируем нажатие на HOME, сворачивая приложение Intent i = new Intent(Intent.ACTION_MAIN); i.addCategory(Intent.CATEGORY_HOME); i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(i); //в зависимости от версии оси намертво убиваем приложение if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { finishAndRemoveTask(); } else { if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) { finishAffinity(); } else { finish(); } } //и контрольный в голову Process.killProcess(Process.myPid());

You have to, or you have to appoint, a Tulbar ection-Bar so that he's got to activate this:toolbar = ...; setSupportActionBar(toolbar); Or hang your push-up listener like:toolbar.setOnMenuItemClickListener(new Toolbar.OnMenuItemClickListener() { @Override public boolean onMenuItemClick(final MenuItem item) { Log.d("TAG", "Menu CLICKED!"); return false; } }

You're looking for a tulbar in the activate, and he's not there, according to you. Look for him in the fragment.@Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { //Toolbar toolbar = (Toolbar) getActivity().findViewById(R.id.my_app_bar); //((AppCompatActivity) getActivity()).setSupportActionBar(toolbar); //return inflater.inflate(R.layout.fragment_training, container, false); View v = inflater.inflate(r.layout.fragment_training, container, false); Toolbar toolbar = (Toolbar) v.findviewbyid(r.id.my_app_bar); ((AppCompatActivity) getActivity()).setSupportActionBar(toolbar); return v; }

It's hard to tell you why you don't have the first one. acivity'Cause you've only shown the marking, but the second one. activity Looks like you got a white screen from the method. onCreateTotal SecondActivity.java Try to replace that:public class SecondActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) { super.onCreate(savedInstanceState, persistentState); setContentView(R.layout.activity_second); //Intent intent = getIntent(); Button back_btn = (Button)findViewById(R.id.back_btn); back_btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { startActivity(new Intent(SecondActivity.this, MainActivity.class)); } }); } } This:public class SecondActivity extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_second); //Intent intent = getIntent(); Button back_btn = (Button)findViewById(R.id.back_btn); back_btn.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { startActivity(new Intent(SecondActivity.this, MainActivity.class)); } }); } }

To move from one to another seven, I'd advise you to do something like that. In your main activation (MainActivity describe the following:View.OnClickListener onClickListener = new View.OnClickListener() { @Override public void onClick(View view) { switch (view.getId()) { case R.id.buttonFirst: start(FirstActivity.class); break; case R.id.buttonSecond: start(SecondActivity.class); break; ... ... case R.id.buttonSeven: start(SevenActivity.class); break; } } }; buttonFirst = (Button) findViewById(R.id.buttonFirst); buttonFirst.setOnClickListener(onClickListener); buttonSecond = (Button) findViewById(R.id.buttonSecond); buttonSecond.setOnClickListener(onClickListener); ... ... buttonSeven = (Button) findViewById(R.id.buttonSeven); buttonSeven.setOnClickListener(onClickListener); And below in the same class, finish the following method:private void start(Class activity) { startActivity(new Intent(MainActivity.this, activity)); }

I did. The sweater pro was right.