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How to use onBackPress button in fragment on Android

In my application I have NavigationView and into this NavigationView I have set menu for open some fragments!
<android.support.design.widget.NavigationView
android:id="#+id/nav_view"
android:layout_width="320dip"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="#000"
android:fitsSystemWindows="true"
app:headerLayout="#layout/tester_drawer_header"
app:itemIconTint="#fff"
app:itemTextColor="#fff"
app:menu="#menu/tester_drawer_main"/>
I want when click on this menu open one fragment and I want when go to nested fragments and press onBack button open first fragment not open backStack fragments!
I write below codes, but after click on back button back fragments from backStack, but I want just open first fragment!
MyActivity codes:
public class TesterDashboardActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_tester_dashboard);
loadFragment(new TesterTestListFragment(), userName);
}
#Override
public void onBackPressed() {
fragmentBackCount = getSupportFragmentManager().getBackStackEntryCount();
if (fragmentBackCount <= 1) {
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
//finishAffinity();
super.onBackPressed();
}
} else {
getSupportFragmentManager().popBackStack();
}
}
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item) {
int id = item.getItemId();
switch (id) {
case R.id.nav_home:
loadFragment(new TesterTestListFragment(), userName);
break;
case R.id.nav_billing:
loadFragment(new TesterFinanceFragment(), context.getString(R.string.menu_billing));
break;
case R.id.nav_edit_profile:
loadFragment(new TesterProfileFilterEditFragment(), context.getString(R.string.menu_edit_profile));
break;
case R.id.nav_bank:
loadFragment(new TesterShebaFragment(), context.getString(R.string.menu_bank));
break;
case R.id.nav_report:
loadFragment(new TesterReportsFragment(), context.getString(R.string.menu_report));
break;
case R.id.nav_setting:
loadFragment(new TesterSettingFragment(), context.getString(R.string.menu_setting));
break;
}
drawer.closeDrawer(GravityCompat.START);
return true;
}
public void loadFragment(Fragment fragment, String toolbarTitle) {
FragmentManager fm = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fm.beginTransaction();
fragmentTransaction.replace(R.id.testerFragment, fragment,TAG_FRAGMENT);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
toolbar.setTitle(toolbarTitle);
}
How can I fix it?

In your code I found when the fragmentBackCount>1 you just call getSupportFragmentManager().popBackStack(); once, so you will see top fragment on backstack.
I think you should call getSupportFragmentManager().popBackStack();, fragmentBackCount-1 time to reach the first fragmnet
else {
for(int i=0;i<fragmentBackCount-1;i++)
getSupportFragmentManager().popBackStack();
}

When you are transitioning between Fragments, call addToBackStack() as part of your
FragmentTransaction:
FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();

Adding navigation drawer from second activity to activity_main. Using .opendrawer in main activity to open second

I have created a project int activity_main and want to add a Navigation drawer to it.
I have gone into the java folder. Right click > new > Actvity > Navigation Drawer activity.
Note: I DON't have an action bar, to create the menu button(3 stacked lines)
Now I don't know how to actually open the navigation drawer over activity_main, without the app crashing.
Thanks.
I've tried doing an on click listener with a button which has
the drawer layout defined as dl (DrawerLayout dl = (DrawerLayout)findviewbyIOd(R.id.Drawer_layout))
and have done
dl.openDrawer(Gravity.LEFT);
have tried putting the code from the NavDrawer activity into the activity_main, but app won't start.
public class MainActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {
Switch OnOff;
EditText editText;
int NumberPicked;
int NumberPicked2;
private DrawerLayout dl;
private ActionBarDrawerToggle abdt;
Values[] troughvals = new Values[8];
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BobbleSelector BS = new BobbleSelector();
final DrawerLayout dl = (DrawerLayout)findViewById(R.id.dl);
Button btnChange = (Button) findViewById(R.id.btnChange);
Switch OnOff = (Switch) findViewById(R.id.OnOff);
NumberPicker numberPicker2 = findViewById(R.id.numberPicker2);
NumberPicker numberPicker = findViewById(R.id.numberPicker);
numberPicker.setMinValue(00);
numberPicker2.setMinValue(00);
numberPicker2.setMaxValue(23);
numberPicker.setMaxValue(23);
btnChange.setOnClickListener( new View.OnClickListener(){
public void onClick(View v){
dl.openDrawer(Gravity.LEFT);
}
});
OnOff.setTextOff("On");
OnOff.setTextOn("Off");
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
return abdt.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}
public void handleSwitchClick(View view) {
Switch s = (Switch) view;
boolean isChecked = s.isChecked();
}
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked){
switch (compoundButton.getId()){
case R.id.OnOff:
break;
}
}
}
Note: have disabled fab, because it could not be found in my project.
I have created a custom Menu for the Navigation Drawer
public class BobbleSelector extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bobble_selector);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Button fab = findViewById(R.id.btnChange);
// fab.setOnClickListener(new View.OnClickListener() {
// #Override
// public void onClick(View view) {
// Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
// .setAction("Action", null).show();
// }
// });
DrawerLayout drawer = findViewById(R.id.dl);
NavigationView navigationView = findViewById(R.id.nav_view);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
navigationView.setNavigationItemSelectedListener(this);
}
#Override
public void onBackPressed() {
DrawerLayout drawer = findViewById(R.id.dl);
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else {
super.onBackPressed();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.bobble_selector, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#SuppressWarnings("StatementWithEmptyBody")
#Override
public boolean onNavigationItemSelected(MenuItem item) {
// Handle navigation view item clicks here.
int id = item.getItemId();
DrawerLayout drawer = findViewById(R.id.dl);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
Drawer Layout
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/dl"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<include
layout="#layout/app_bar_bobble_selector"
android:layout_width="match_parent"
android:layout_height="match_parent" />
<android.support.design.widget.NavigationView
android:id="#+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="#layout/nav_header_bobble_selector"
app:menu="#menu/nav_menu" />
</android.support.v4.widget.DrawerLayout>
From Logcat
2019-06-02 13:13:08.195 12745-12745/com.example.mytest E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mytest, PID: 12745
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.widget.DrawerLayout.openDrawer(int)' on a null object reference
at com.example.mytest.MainActivity$1.onClick(MainActivity.java:49)
at android.view.View.performClick(View.java:6294)
at android.view.View$PerformClick.run(View.java:24770)
at android.os.Handler.handleCallback(Handler.java:790)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:440)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Expected to open drawer with the changebutton.openDrawer(Gravity.Left) But crashes the app.

Found I needed to move the code relating to the nav bar to the bottom of OnCreate and set the "SetContentView()" to be the layout for the Navigation bar.
Then it worked perfectly.
Before
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = findViewById(R.id.btnChange);
drawer = findViewById(R.id.dl);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer, R.string.navigation_drawer_open,R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();
//Not nav
Switch OnOff = (Switch) findViewById(R.id.OnOff);
NumberPicker numberPicker2 = findViewById(R.id.numberPicker2);
NumberPicker numberPicker = findViewById(R.id.numberPicker);
numberPicker.setMinValue(00);
numberPicker2.setMinValue(00);
numberPicker2.setMaxValue(23);
numberPicker.setMaxValue(23);
OnOff.setTextOff("On");
OnOff.setTextOn("Off");
//not nav
}
After
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = findViewById(R.id.btnChange);
//Not nav
Switch OnOff = (Switch) findViewById(R.id.OnOff);
NumberPicker numberPicker2 = findViewById(R.id.numberPicker2);
NumberPicker numberPicker = findViewById(R.id.numberPicker);
numberPicker.setMinValue(00);
numberPicker2.setMinValue(00);
numberPicker2.setMaxValue(23);
numberPicker.setMaxValue(23);
OnOff.setTextOff("On");
OnOff.setTextOn("Off");
//not nav
setContentView(R.layout.activity_bobble_selector);
drawer = findViewById(R.id.dl);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer, R.string.navigation_drawer_open,R.string.navigation_drawer_close);
assert drawer != null;
drawer.addDrawerListener(toggle);
toggle.syncState();
}

How can I override the button display home

By default the button(setDisplayHomeAsUpEnabled), returns the parent activity, how would I change it? For example: I need to back to a Intent
toolbar = (Toolbar) findViewById(R.id.tb_dados);
toolbar.setTitle("Adicione uma descrição");
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);

You can try this....
#Override
public boolean onOptionsItemSelected(MenuItem item)
{
switch (item.getItemId())
{
case android.R.id.home:
// your intent code here.
break;
}
return super.onOptionsItemSelected(item);
}

you can use onOptionsItemSelected method and perform any other function if you want
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
Toast.makeText(this, "back Button Clicked", Toast.LENGTH_SHORT).show();
return true;
}
return super.onOptionsItemSelected(item);
}

Since you are using custom toolbar so you can easily use custom toolbar like this
toolbar.setNavigationIcon(R.drawable.back_arrow);// use your back arrow image
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(this,MainActivity.class));//call which activity you want in back press
finish();
}
});

Android Up button not working

I am trying to manually implement the actions that must take place when the up button on the actionbar is pressed but for some reason nothing happens when I press it.
here is my code:
public class ActivityOne extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_activity_one);
Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar_actionbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
Button button = (Button)findViewById(R.id.btn1);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
openActivityTwo();
}
});
Button button2 = (Button)findViewById(R.id.btn2);
button2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
openActivityThree();
}
});
}
void openActivityTwo(){
Intent intent = new Intent(this, ActivityTwo.class);
startActivity(intent);
}
void openActivityThree(){
Intent intent = new Intent(this, ActivityThree.class);
startActivity(intent);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_activity_one, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
else if(id == R.id.homeAsUp){
Log.i("","Up is pressed");
finish();
return true;
}
return super.onOptionsItemSelected(item);
}
}
I understand that I have to explicitly assign a parent activity for the activity I want to implement up navigation on the manifest file, but problem is that this activity has multiple parents so I thought calling the finish() method when the up button is pressed on this activity will be the better approach.
I have already tried both id == R.id.home and id == R.id.homeAsUp and they both do not work. I do not know if it is because I am using AppCompactActivity or what Please help

Here is how you can implement this, try this code
use android.R.id.home instead of R.id.home or R.id.homeAsUp
public boolean onOptionsItemSelected(final MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
//use onBackPressed() OR finish();
return true;
default:
return super.onOptionsItemSelected(item);
}
}

The correct way to do it is to override public boolean onNavigateUp() just like overriding onBackPressed().

Using android studio 3.6.2 I've found that the Up button is not displayed by default in my apps, but it can be easily added..
Go to AndroidManifest.xml and update each activity that needs an Up button as follows:
<activity
android:name=".yourClassName"
android:parentActivityName=".MainActivity">
<meta-data android:name="android.support.PARENT_ACTIVITY"
android:value="com.example.yourPackageName" />
</activity>
The target destination for the Up button is set by changing parentActivityName. In this example I have set it as '.MainActivity' but you can change that to whatever activity you want the user to navigate to.

Using one navigation drawer that shows different options depending on the activity that is currently showing

I am trying to implement a navigation drawer in a BaseActivity, that shows different options depending on the activity that is currently showing. For that, I developed a BaseActivity, that implements the navigation drawer, and decides what to show, depending on the activity that is currently showing. The purpose of this, is to make all other activities that need to use the navigation drawer, expand the BaseActivity.
The following code, shows no errors, but the navigation drawer shows itself completely empty, and does not show when I click the 'home' button, neither the 'menu' button, a functionality that I implemented with the 'onKeyDown' method. It just shows, when I use the following gesture: move the finger from the left to the right in the left side of the screen.
When I do the same in each class I need, instead of using a BaseActivity, everything works perfeclty fine.
I have been trying this for days now and I still do not understand why, the content of the navigation drawer is still not showing. I would appreciate some help please. Thanks in advance.
Here, the core classes of the problem:
BaseActivity.java
public abstract class BaseActivity extends ActionBarActivity
{
public DrawerLayout drawerLayout = null;
public ActionBarDrawerToggle drawerToggle = null;
public Activity currentActivity = null;
public ArrayList<Item> navDrawerItems = new ArrayList<Item>();
public ItemListAdapter adapter = null;
public ListView drawerList = null;
int id = 0;
protected void onCreate(Bundle savedInstanceState, int resLayoutID)
{
super.onCreate(savedInstanceState);
setContentView(resLayoutID);
currentActivity = this;
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
drawerToggle = new ActionBarDrawerToggle(currentActivity,
drawerLayout,
R.drawable.ic_drawer,
R.string.open_menu,
R.string.close_menu)
{
public void onDrawerClosed(View view)
{
Log.e("", "Close drawer");
getSupportActionBar().setTitle(getTitle());
ActivityCompat.invalidateOptionsMenu(currentActivity);
}
public void onDrawerOpened(View drawerView)
{
Log.e("", "Open drawer");
getSupportActionBar().setTitle(getTitle());
ActivityCompat.invalidateOptionsMenu(currentActivity);
}
};
drawerLayout.setDrawerListener(drawerToggle);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
// Populate navigation drawer depending on the activity
// that is currently showing.
if (this.getClass().getSimpleName().equals("Z"))
setUpNavigationForZActivity();
}
private void setUpNavigationForZActivity()
{
Log.e("", "In setUpNavigationForZActivity");
// Prepare list items.
id = R.string.title_activity_A;
navDrawerItems.add(new NavigationDrawerItem(getString(id), Utils.activityIcon().get(id)));
id = R.string.title_activity_B;
navDrawerItems.add(new NavigationDrawerItem(getString(id), Utils.activityIcon().get(id)));
// Populate view.
drawerList = (ListView) findViewById(R.id.left_menu);
adapter = new ItemListAdapter(currentActivity, navDrawerItems;
drawerList.setAdapter(adapter);
drawerList.setOnItemClickListener(new OnItemClickListener()
{
public void onItemClick(AdapterView<?> parent, View view, int position,
long id)
{
Intent intent = null;
switch(position)
{
case 0:
intent = new Intent(currentActivity, A.class);
startActivity(intent)
break;
case 1:
intent = new Intent(currentActivity, B.class);
startActivity(intent)
break;
default:
}
}
});
}
#Override
public boolean onOptionsItemSelected(MenuItem item)
{
if (drawerToggle.onOptionsItemSelected(item))
return true;
return super.onOptionsItemSelected(item);
}
#Override
protected void onPostCreate(Bundle savedInstanceState)
{
super.onPostCreate(savedInstanceState);
drawerToggle.syncState();
}
#Override
public void onConfigurationChanged(Configuration newConfig)
{
super.onConfigurationChanged(newConfig);
drawerToggle.onConfigurationChanged(newConfig);
}
#Override
public boolean onKeyDown(int keyCode, KeyEvent e)
{
Log.e("", "onKeyDown");
if (keyCode == KeyEvent.KEYCODE_MENU)
{
if(!drawerLayout.isDrawerOpen(Gravity.LEFT))
drawerLayout.openDrawer(Gravity.LEFT);
else
drawerLayout.closeDrawer(Gravity.LEFT);
}
return super.onKeyDown(keyCode, e);
}
}
Z.java
public class Z extends BaseActivity
{
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState, R.layout.Z);
setContentView(R.layout.Z);
//Other things to do...
}
}
Z.xml
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<!-- Main content view -->
<ScrollView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:fillViewport="true" >
// Other layout and views configurations...
</ScrollView>
<!-- Navigation drawer -->
<ListView
android:id="#+id/left_menu"
android:layout_width="240dp"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="#color/gray_7_5"
android:choiceMode="singleChoice" />
</android.support.v4.widget.DrawerLayout>

I do not exactly know why you would want to implement it that way but if you still want to do it this way i would suggest making your navdrawer use a listview with an adapter to draw items from an array and then have your base activity have a getData() call that you can override in your derived activities that will supply the data that the Adapter so that the listview will then draw the appropriate items in the navdrawer. You will then have to implement the onItemClick event for each listview per activity.