My app has two activities, the main one is working well but when opening the login one it crashes with the following error:
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
Here's the fragment of my code referred to the toolbar (It's basically the login activity + the toolbar I want to add):
public class LoginActivity extends AppCompatActivity implements LoaderCallbacks<Cursor> {
Toolbar toolbar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.inflateMenu(R.menu.mainmenu);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Toolbar and menu are working well on my main activity. Toolbar is also in the XML layout for the login activity.
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v7.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference...
This NPE intimate you to first of all set the toolbar
You are not setting the toolbar..First of all set it...
Do like this...
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
toolbar = (Toolbar) findViewById(R.id.toolbar);
// toolbar.inflateMenu(R.menu.mainmenu);
setSupportActionBar(toolbar)
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
you don't need to use toolbar.inflateMenu() because the Toolbar is acting as your ActionBar. The only time you need to call toolbar.inflateMenu() is when you are using the Toolbar as a standalone widget. You can handle menu item click events by using the following lines of code...
toolbar.setOnMenuItemClickListener(
new Toolbar.OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(MenuItem item) {
// Handle menu item click event here
return true;
}
});
Hope this will help you
call setSupportActionBar(toolbar); before getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Related
I want to show an ActionBar in my Activity while only showing a closing symbol. Therefore I used the method getSupportActionBar():
getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_close);
setTitle("Add Event");
But it throws a NullPointerExeption because apparently there's no ActionBar to call:
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tutorial/com.example.tutorial.AddEventActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.appcompat.app.ActionBar.setHomeAsUpIndicator(int)' on a null object reference
In my MainActivity I implemented a Drawer Navigation where I already used a toolbar that works:
public class MainActivity extends AppCompatActivity {
protected DrawerLayout mDrawer;
private Toolbar toolbar;
private NavigationView nvDrawer;
// Make sure to be using androidx.appcompat.app.ActionBarDrawerToggle version.
private ActionBarDrawerToggle drawerToggle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set a Toolbar to replace the ActionBar.
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// This will display an Up icon (<-), we will replace it with hamburger later
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
// Find our drawer view
mDrawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerToggle = setupDrawerToggle();
// Setup toggle to display hamburger icon with nice animation
drawerToggle.setDrawerIndicatorEnabled(true);
drawerToggle.syncState();
// Tie DrawerLayout events to the ActionBarToggle
mDrawer.addDrawerListener(drawerToggle);
// Find our drawer view
nvDrawer = (NavigationView) findViewById(R.id.nvView);
// Setup drawer view
setupDrawerContent(nvDrawer);
}
How do I fix that?
Thanks in advance!
Replace this line :
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
with this line :
ActionBar actionBar = getSupportActionBar();
actionBar.setDisplayHomeAsUpEnabled(true);
This should solve your problem.
You may try to add following attribute to your MainActivity item under your ActivityManifest.xml
android:theme="#style/Theme.AppCompat.Light.DarkActionBar"
Then try to access it with the getSupportActionBar(). With this way you can choose the activities that you don't or do want to include actionbars by using relevant themes. For example:
<activity
android:name=".SecondActivity"
android:theme="#style/Theme.AppCompat.Light.DarkActionBar"
android:parentActivityName=".MainActivity" />
I have a generic
MyActivity extends AppCompatActivity
I don't override the toolbar with a custom xml defined toolbar, just use the generated one Android provides.
I can set the title via your normal
getSupportActionBar().setTitle("foo");
but setting the subtitle via
getSupportActionBar().setSubtitle("bar");
doesn't set it. It remains blank. I'm doing this onCreate()
(I feel I've done this many times before with no fail)
Although I've noticed if I visit another activity, then return, the subtitle would then show... not on orientation change, not on recreate() but only when I'm returning from an activity.
I'm experiencing this on 5.0 and 7.0
For the time being I'll likely define my own Toolbar and move forward since that seems where most people have solutions for this same problem.
Relevant code:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_replenishment_list);
ButterKnife.bind(this);
MyApplication.getInstance().getComponent().inject(this);
setupUI();
}
private void setupUI() {
setupActionBar();
}
private void setupActionBar() {
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
//TODO: not working unless activity is recreated...
// explore custom xml defined toolbar
//actionBar.setTitle("different title than what is defined in manifest"); <-- this does work, but not this
actionBar.setSubtitle(UserUtil.getFormattedFirstNameLastName(userService.getUserFromJWT(), this));
}
}
I have put the below code in my onCreate() method.
ActionBar actionBar = getActionBar();
if (actionBar==null) {
System.out.println("TEST NULL");
} else {
System.out.println("TEST NOT NULL");
}
The result is null. When I add the toolbar first it works fine.
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
ActionBar actionBar = getActionBar();
actionBar.setSubtitle("TESTING");
Your getSupportActionBar or getActionBar will return null if you didn't set toolbar to it. You need to set the toolbar to your action bar before using getSupportActionBar or getActionBar.
I'm using android.support.v7.widget.Toolbar and AppCompatActivity. I've enabled back up button like this supportActionBar.setDisplayHomeAsUpEnabled(true);.
The fragment in side the activity will set the title and subtitle in onResume() like this
AppCompatActivity activity = (AppCompatActivity) getActivity();
activity.setTitle(title);
activity.getSupportActionBar().setSubtitle("Bingo");
The problem is, when the fragment shows up onResume is called but subtitle is not shown. When I press power OFF and ON, means fragment goes to pause and resumes again. Now, subtitle is visible. I've tested on other android phone as well.
Can you please help me finding out the problem?
This is because the toolbar is not rendered when you are setting the subtitle.
Try this code,Set title and subtitle inside this method
private void setupToolbar(){
toolbar = (Toolbar) findViewById(R.id.detail_toolbar);
if(toolbar != null){
setSupportActionBar(toolbar);
}
toolbar.post(new Runnable()
{
#Override
public void run()
{
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setTitle(mTitle);
getSupportActionBar().setSubtitle("Subtitle);
}
});
}
I am the android developer (freshers).
Here is my java code. where I have tried TabSpec.addTab(.......) but it gives me error of nullpointerexception. plz let me know what should I do? please provide me the code for tabhost with xml and java...thank you.
public class HomeActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
getSupportActionBar().setTitle(null);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
}
Is this the error where I use supportactionbar methods?
please help me I want to use these tabs with the listview and searchview..
thank you.
I am trying to set up my Navigation Drawer listener for my MainScreen activity. When I set everything up, my app crashes when I try use ActionBarDrawerToggle. Are there other ways of implementing this?
Unable to start activity ComponentInfo{koeksworld.com.firstandroidproject/koeksworld.com.firstandroidproject.UserMainPanel}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.widget.DrawerLayout.setDrawerListener(android.support.v4.widget.DrawerLayout$DrawerListener)' on a null object reference
Here is some of the code in my activity:
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_user_main_panel);
listener = new NavigationDrawerItemListener(this);
Toolbar toolbar = (Toolbar) findViewById(R.id.groceryAppHomeToolbar);
homeDrawer = (DrawerLayout) findViewById(R.id.mainDrawerLayout);
homeListView = (ListView) findViewById(R.id.homeListView);
homeListView.setBackgroundColor(getResources().getColor(R.color.colorBlue));
navigationArray = getResources().getStringArray(R.array.navigationArray);
navigationAdapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1,
navigationArray);
homeListView.setAdapter(navigationAdapter);
homeListView.setOnItemClickListener(listener);
//The suspected culprit
drawerListener = new ActionBarDrawerToggle(this, homeDrawer, toolbar, R
.string
.open_drawer, R
.string.close_Drawer);
homeDrawer.setDrawerListener(drawerListener);
drawerListener.syncState();
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayShowTitleEnabled(false);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
}
Make sure you are using the same id for the navigation drawer in findViewById(R.id.mainDrawerLayout) and in the layout file.
Seems mDrawerLayout is null when calling .setDrawerListener()