Develop Reference

bottom navigation bar in android application

I develop an android application and I need to prevent the user to close the application from navigation bar buttons .. there is another way to close the application.
I search a lot and didn't find any way to Permanently hide bottom navigation bar or at least stop all button control

Use this method to disable the Home button
#Override
public void onAttachedToWindow() {
this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
super.onAttachedToWindow();
}

If you meant to disable the back button on device, you could override
#Override
public void onBackPressed() {
super.onBackPressed(); //delete or comment this line
.......//do something you want
}

Animation on Android Toolbar Back Button

I have an activity wich has a Toolbar which displays a back button.
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar_about"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="?attr/colorPrimary"
android:minHeight="?attr/actionBarSize"
android:theme="?attr/actionBarTheme"
app:title="#string/app_name"
/>
The back button is enabled like this:
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar_about);
setSupportActionBar(toolbar);
//noinspection ConstantConditions
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
I call this activity from my main activity like this:
Intent intent = new Intent(this, AboutActivity.class);
startActivity(intent);
The Activity's parent is defined in the manifest
<activity android:name=".AboutActivity">
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value=".EntryActivity" />
</activity>
So far everything works fine, except that the transition animation is wrong when using the back button in the Toolbar.
When I open the activity, it slides in from the right.
When I press the phone's physical back button it slides out to the right again. This is correct.
However when using the Toolbar back button it slides out to the left. This looks wrong. How can I change this, so it duplicates the behaviour of the physical back button?

When you press the Actionbar Up button, AppCompatActivity detects this button press in its onMenuItemSelected() call, and invokes onSupportNavigateUp(). This method determines the "parent activity" Intent and uses that to navigate up. Because it's using an Intent to (re-)open the previous activity, it uses the same animation it would for opening a "new" screen.
Assuming you don't care about the particular niceties of the "Up Navigation" pattern (which it sounds like you do not, as comments have led me to believe you don't have lateral navigation and you can't get to your second activity from anywhere other than your first activity), you can side-step all of this built-in "up" behavior by overriding the onSupportNavigateUp() method.
#Override
public boolean onSupportNavigateUp() {
finish();
return true;
}
This will mean that pressing the Actionbar Up button always simply finish()es your activity, so (like I said before) you lose out on all the smart built-in "up" behavior... but you didn't want that anyway.
You could also handle the Actionbar Up button in onOptionsItemSelected(), but I prefer the other way since I think it's a little more obvious that you're hijacking the system's up behavior.
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
finish();
return true;
}
return super.onOptionsItemSelected(item);
}
With either of these in place, you can remove the "parent" definitions from your manifest, since now they're not used.

Try this:
override fun onSupportNavigateUp(): Boolean {
onBackPressed()
return true
}

This is because the default launchMode of activities is standard.
The documentation of standard states the following:
The system always creates a new instance of the activity in the target task and routes the intent to it.
You can solve this by using android:launchMode="singleTop" on the parent/starting activity.
If an instance of the activity already exists at the top of the target task, the system routes the intent to that instance through a call to its onNewIntent() method, rather than creating a new instance of the activity.
For more information see Tasks and the back stack and android:launchMode.

Android navigation drawer exits on back pressed

I am using navigation drawer in my MainActivity.java to switch fragments and I am also extending my MainActivity to the other activities in my app. Now the problem is that, when I press back button during I am on fragment, the app suddenly exits without any notification. And if I use OnBackPressed in my MainActivity it is bydefault implemented to the other activities extending main activity too and when I press back button to any of that acivity it asks me first for confirmation and then comes back to previous activity or frag. Need a solution to avoid this. I want to set onbackpessed or anything that shows dialogue or asks for confirmation to exit app on fragments only but dont know howto do.
Or any help regarding fragment back stacking to open a fixed fragment on back button pressed is welcomed if it tells how to change the title of hence opened fragment too.

call onBackPressed() in that activity in which you have put all fragment or main activity
#Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() == 0) {
//Display your dialog here
} else {
getFragmentManager().popBackStack();
}
}
Other solution
#Override
public void onBackPressed() {
if (slidingMenu.isMenuShowing()) {
slidingMenu.toggle(true);
} else {
super.onBackPressed();
//Display your dialog
}
}
This is works for me.

Updating navigation drawer after back press

I'm implementing an Android application with a Navigation Drawer and I have a problem with it.
I started from the template (Android app with navigation drawer) in Android studio and added a new section to it - Settings. When clicking the settings button the user is taken to a new Activity and the user can go BACK either by pressing the "up" button in the action bar (Which works perfectly) or by pressing the physical back button. That part doesn't work so good.
When pressing the "up" button and then opening the navigation bar, my home page is highlighted (selected). But when using the back button and opening the navigation drawer, the Settings item is selected, as if the user is viewing that page and not the home page.
So this is because the Navigation Drawer fragment isn't updated and I havent found any way to solve this problem. What I would like is for the Navigation Drawer to be recreated (Which is what I think happens when pressing the "up" button). Do you know how I can make this happen?
I started working on a solution based on this:
getSupportFragmentManager().addOnBackStackChangedListener(
new FragmentManager.OnBackStackChangedListener() {
public void onBackStackChanged() {
// Update your UI here.
}
});
But I don't know what to write there that will update the whole UI. (experimented with calling onCreate() but it's too ugly and can't be the right way).
Any suggestions?
UPDATE:
The onBackStackChanged event isn't sent when pressing BACK from another activity. Only for fragments in the current actvity.

You have to override the actionbar back button like this :
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// TODO Auto-generated method stub
switch (item.getItemId()) {
case android.R.id.home:
this.finish();
//or
super.onBackPressed();
break;
}
return true;
}

I had the same problem.I used notifyDataSetChanged() in the ListView Adapter.
In getView() i used,
if(mListView.isItemChecked(position)) {
convertView.setBackgroundColor(getResources().getColor(R.color.md_black_1000_12));
}else{
convertView.setBackgroundColor(getResources().getColor(android.R.color.transparent));
}
notifyDataSetChanged();

How to refresh the screen when back button is pressed

I have scenario with two screens.
Screen 1 shows data from from API in list format
There is a "+" button in menu bar
Clicking this button takes user to screen 2
User can enter some info on screen 2 and press the "save" button on top of this screen. This does a POST to my API and saves the data.
After saving, I would like to put the user back to screen 1. I've done that with this:
#Override
public boolean onOptionsItemSelected(MenuItem menuItem) {
if (menuItem.getTitle().toString().equalsIgnoreCase("save")) {
new CreateSomethingTask(this,enteredName.getText().toString(), id).execute();
Intent listscreen = new Intent(getApplicationContext(), ShowListActivity.class);
startActivity(listscreen);
return true;
}
return true;
}
However, the added item is not shown. If I close my app and open it again then the item shows up.
Is there a good way to handle this? I like how the Github Android app handles this when creating a new Gist. But I'm not sure how to implement that.

You should start your screen2 with startActivityForResult(). That way you could send a result back and a code and proceed to refresh your screen1. See example : How to manage `startActivityForResult` on Android?

Below function maybe help you, didn't tried.
#Override
public void onAttachedToWindow() {
super.onAttachedToWindow();
callFunctionToRefreshList();
//or redraw data from api
//setContentView(R.layout.activity_book);
}