I have the following code, the project is migrated to andoidx, R.id.viewpager returns can not find symbol variable viewpager SimpleFragmentPagerAdapter is a custom(an extention of)
FragmentPagerAdapter and is working well
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Set the content of the activity to use the activity_main.xml layout file
setContentView(R.layout.activity_catagory);
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
// Create an adapter that knows which fragment should be shown on each page
SimpleFragmentPagerAdapter adapter = new SimpleFragmentPagerAdapter(getSupportFragmentManager());
// Set the adapter onto the view pager
viewPager.setAdapter(adapter);
}
}
Related
I am developing an Android app that has a little bit confusing navigation structure which leads me to my problem. There are two ways to navigate through the app. First is the BottomNav and second is a TabMenu. I thought about working with fragments that replace each other, so I came up with the following structure:
1. BottomNav#1
- TabMenu#1
- Tabmenu#2
- TabMenu#3
- ...
2. BottomNav#2
- TabMenu#4
- Tabmenu#5
- TabMenu#6
- ...
... and so on.
The problem I am facing is that when I navigate from BottomNav#1 to BottomNav#2 and back again there is a blank screen that doesn't show the content of the actual fragment:
When I open the app
After clicking on BottomNav#2 and then back to BottomNav#1 the fragment seems to be blank
My guess is that I somehow have a problem with my fragmentTransaction.replace(); as it seems like the fragment doesn't get loaded again? I am kind of new to this and really tried to find an answer online but this is a bit specific why I guess I didn't find anything.
This is my MainActivity:
package com.example.XXXX;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.widget.FrameLayout;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
private FrameLayout mMainFrame;
private AusweisFragment ausweisFragment;
private SpendenFragment spendenFragment;
#Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ausweisFragment = new AusweisFragment();
spendenFragment = new SpendenFragment();
BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
}
private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
= new BottomNavigationView.OnNavigationItemSelectedListener()
{
#Override
public boolean onNavigationItemSelected(#NonNull MenuItem item)
{
switch (item.getItemId())
{
case R.id.navigation_ausweis:
setFragment(ausweisFragment);
return true;
case R.id.navigation_spenden:
setFragment(spendenFragment);
return true;
}
return false;
}
};
private void setFragment(Fragment fragment)
{
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.replace(R.id.main_frame, fragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
}
This should lead to e.g. the fragment called "ausweis" by clicking on on BottomNav#1 (switch case):
package com.example.XXXXXXX;
import android.app.Activity;
import android.os.Bundle;
import android.support.design.widget.TabItem;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class AusweisFragment extends Fragment {
private View rootView;
private AusweisPageAdapter ausweisPageAdapter;
private TabLayout tabLayout;
private ViewPager viewPager;
public AusweisFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
rootView= inflater.inflate(R.layout.fragment_ausweis, container, false);
tabLayout = rootView.findViewById(R.id.tablayoutAusweis);
viewPager = rootView.findViewById(R.id.viewPagerAusweis);
ausweisPageAdapter = new AusweisPageAdapter(getActivity().getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(ausweisPageAdapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener()
{
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
return rootView;
}
}
After that I would like to call another fragment called "spenden" which is exactly the same as the fragment called "ausweis" but with different named tabs, so I think it is not bother you with more code.
edit: I missed about writing where the "content" I wrote about gets from. For a first try and proof that the fragments change, I hardcoded a phrase like "Ausweis" into the XML which is connected to my fragment java class.
Maybe one of you has an idea to that problem. I think it has something to do with my onCreateView in one of the fragments, but I have no close clue.
Hopefuly I didn't miss an important detail. I am very grateful for any kind of help. Thanks a lot in advance.
The answer to my problem was to use a child-parent relation between the different fragments. With the click on BottomNav#1 I am inflating an fragment which inflates a new fragment inside itself. That was the key problem. In my code I handled this as a second "normal" getFragmentManager();.
The answer is to use getChildFragmentManager(); for the nested fragment instead. Like this:
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
rootView= inflater.inflate(R.layout.fragment_ausweis, container, false);
tabLayout1 = rootView.findViewById(R.id.tablayoutAusweis);
viewPager = rootView.findViewById(R.id.viewPagerAusweis);
ausweisPageAdapter = new AusweisPageAdapter(getChildFragmentManager(), tabLayout1.getTabCount());
viewPager.setAdapter(ausweisPageAdapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout1));
...
...
Hopefuly this will help some people when they face the same problem with nested fragments.
This question already has answers here:
Android - activity_main cannot be resolved or is not a field
(11 answers)
Closed 6 years ago.
I'm facing a problem. I am getting the error "Cannot resolve symbol 'activity_main'. I read the other posts about it, and could not figure out how to fix it. Here is my code :
package com.grasland.musicplayer.Activities;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import com.grasland.musicplayer.R;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get the ViewPager and set it's PagerAdapter so that it can display items
ViewPager viewPager = (ViewPager) findViewById(R.id.viewpager);
viewPager.setAdapter(new SampleFragmentPagerAdapter(getSupportFragmentManager(),
MainActivity.this));
// Give the TabLayout the ViewPager
TabLayout tabLayout = (TabLayout) findViewById(R.id.sliding_tabs);
tabLayout.setupWithViewPager(viewPager);
}
}
There is a screen of my project's tree :
Tree project
Thanks !
Make sure that the name of the main activity's layout file is "activity_main". If its not, rename it to "activity_main". If the name is already correct, try Build → Clean Project.
I want to display custom listview in navigation drawer's fragment page. However, in my fragment class, I'm getting an error which seems I cannot set a custom adapter.
package android_gcm_client.mynavigation;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import java.util.ArrayList;
public class List_Fragment extends Fragment {
View rootview;
ArrayList prgmName;
public static int [] prgmImages= {R.drawable.images,R.drawable.images1,R.drawable.images2,R.drawable.images3,R.drawable.images4,R.drawable.images5,R.drawable.images6,R.drawable.images7,R.drawable.images8};
public static String [] prgmNameList={"Let Us C","c++","JAVA","Jsp","Microsoft .Net","Android","PHP","Jquery","JavaScript"};
#Nullable
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootview=inflater.inflate(R.layout.custom_layout,container,false);
CustomAdapter ca = new CustomAdapter(this,prgmNameList,prgmImages);
ListView listview=(ListView) getView().findViewById(R.id.listView);
listview.setAdapter(ca);
return rootview;
}
}
It seems the error happens in line below (custom adapter can not be applied).
CustomAdapter ca = new CustomAdapter(this,prgmNameList,prgmImages);
In MainActivity I call the fragment as follows:
public void onNavigationDrawerItemSelected(int position) {
// update the main content by replacing fragments
Fragment objFragment=null;
switch(position) {
case 0:
objFragment=new ListFragment();
break;
}
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.container, objFragment)
.commit();
}
I tried different ways to display custom listview for navigation item selected method.
I tried to directly call activity instead of fragment but problem was navigation drawer not visible for all activity. So I tried to call CustomAdapter in activity as I'm doing in fragment.
I have struggle to solve this error. (Sorry for bad English).
You are using this in custom adapter. Usually adapters wants a Context in constructor call. But this constructor is called inside a fragment and this can't be used.
You can use getActivity() as Context inside a Fragment. But.
Sometimes it can return a null if it is called before onAttach() of this fragment.
CustomAdapter ca = new CustomAdapter(getActivity(), prgmNameList, prgmImages);
Also you can use Application context by creating static variable inside your Application class:
public class Application extends android.app.Application {
public static Context AppContext = null;
#Override
public void onCreate() {
super.onCreate();
AppContext = getApplicationContext();
// You can use this line to solve styling problems
// because Manifest android:theme is not working
AppContext.setTheme(R.style.AppTheme);
}
}
and create adapter like this:
CustomAdapter ca = new CustomAdapter(Application.AppContext, prgmNameList, prgmImages);
Can anyone tell me why this isnt working? I havent changed this file since it worked last but now I get the error below:
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.v13.app.FragmentStatePagerAdapter;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
public class MainActivity extends FragmentActivity {
private final static int NUM_PAGES = 2;
private ViewPager mPager;
private ScreenSlidePagerAdapter mAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
// Instantiate a ViewPager and a PagerAdapter.
mPager = (ViewPager) findViewById(R.id.pager);
mAdapter = new ScreenSlidePagerAdapter(getFragmentManager());
mPager.setAdapter(mAdapter);
mPager.setCurrentItem(2);
}
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int i) {
Fragment frag = null;
switch (i) {
case 0:
frag = new PageOneFragment();
break;
case 1:
frag = new PageTwoFragment();
break;
}
return frag;
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
}
The error is on "frag = new PageTwoFragment();" which states "Type mismatch: cannot convert from PageTwoFragment to Fragment".
Maybe I should create two projects from now on, last good version and then current working project. Is this something other people do?
Thanks
The Problem is, that you are mixing Android Fragments how there were introduced in API11 and Fragments from android support library.
You have to use one or the other, but not both.
Change your imports to
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.support.v13.app.FragmentStatePagerAdapter;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
And change getFragmentManager() to getSupportFragmentManager().
And it will work using the support lib.
Calling mPager.setCurrentItem(2); with a pager of 2 Fragments crashs, though.
Only 0 and 1 are valid values in your case.
You imported the wrong Fragment.
You need to import android.support.v4.Fragment
Furthermore, your adapter only handles 2 Fragments. Therefore calling
ViewPager.setCurrentItem(2);
will cause problems, since the index for the first fragment is 0.
I am making a view pager to make a slide show for images. I took code from Android developers, but I was facing some issues, fragment was not recognized, I think it was because my android was 2.33. So to solve that I imported a jar file android.support.v4.jar
My issues were resolved but now I am getting this error that getfragmentmanager() is undefined
and another issue "The method invalidateOptionsMenu() is undefined for the type new ViewPager.SimpleOnPageChangeListener(){}"
Here is my code, can any one please help ??
My platform is 2.3.3 and api level is 10 and in manifest I have this
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
Code :
package com.example.profilemanagment;
import android.support.v4.app.Fragment;
import android.support.v4.app.*;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.NavUtils;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
public class ScreenSlideActivity extends FragmentActivity {
/**
* The number of pages (wizard steps) to show in this demo.
*/
private static final int NUM_PAGES = 5;
/**
* The pager widget, which handles animation and allows swiping horizontally to access previous
* and next wizard steps.
*/
private ViewPager mPager;
/**
* The pager adapter, which provides the pages to the view pager widget.
*/
private PagerAdapter mPagerAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_screen_slide);
// Instantiate a ViewPager and a PagerAdapter.
mPager = (ViewPager) findViewById(R.id.pager);
mPagerAdapter = new ScreenSlidePagerAdapter(getFragmentManager());
mPager.setAdapter(mPagerAdapter);
mPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// When changing pages, reset the action bar actions since they are dependent
// on which page is currently active. An alternative approach is to have each
// fragment expose actions itself (rather than the activity exposing actions),
// but for simplicity, the activity provides the actions in this sample.
invalidateOptionsMenu();
}
});
}
/**
* A simple pager adapter that represents 5 {#link ScreenSlidePageFragment} objects, in
* sequence.
*/
private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
public ScreenSlidePagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
return ScreenSlidePageFragment.create(position);
}
#Override
public int getCount() {
return NUM_PAGES;
}
}
}
Quoting from the docs.
When using this class (FragmentActivity) as opposed to new platform's built-in fragment and loader support, you must use the getSupportFragmentManager() and getSupportLoaderManager() methods respectively to access those features.
Since you are extending FragmentActivity use getSupportFragmentManager()
http://developer.android.com/reference/android/support/v4/app/FragmentActivity.html
Check the docs
FragmentActivity does not have getFragmentManager()