I have a PagerAdapter with two views. Right now I am calling populateList() from the xml by attaching a android:onClick="populateList()" to a button. If I try to call the populateList() from within the Main activity it creates a NullPointerException on my ListView. How do I inflate my view/ListView so that I can use it within the Main activity?
package com.itoxygen.publicsafety;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.os.Bundle;
import android.os.Environment;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ListView;
public class Main extends Activity {
/** Called when the activity is first created. */
EditText alarmLabel;
ArrayList<String> item = new ArrayList<String>();
Dialog alarmDialog;
ArrayAdapter<String> listAdapter;
ListView list;
private List<String> path = null;
private String root;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
root = Environment.getExternalStorageDirectory().getPath(); //gets the root path of SD card
MyPagerAdapter adapter = new MyPagerAdapter();
ViewPager myPager = (ViewPager) findViewById(R.id.threepageviewer);
myPager.setAdapter(adapter);
myPager.setCurrentItem(0);
}
}
public void populateList(View v) {
list.setAdapter(listAdapter);
}
////////////////////////////////////////SWIPE NAVIGATION STUFF///////////////////////////////////////////////////////////////
/**
*
*/
private class MyPagerAdapter extends PagerAdapter {
/**
* Returns how many pages on the main Activity
*/
public int getCount() {
return 2; //increment this if adding pages
}
public Object instantiateItem(View collection, int position) {
LayoutInflater inflater = (LayoutInflater) collection.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
/*
* Add your layouts here
*/
int resId = 0;
switch (position) {
case 0:
resId = R.layout.activity_main_list;
break;
case 1:
resId = R.layout.activity_main_tile;
break;
}
View view = inflater.inflate(resId, null);
((ViewPager) collection).addView(view, 0);
list = (ListView)findViewById(R.id.list);
listAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, item);
return view;
}
public void destroyItem(View arg0, int arg1, Object arg2) { ((ViewPager) arg0).removeView((View) arg2); }
public void finishUpdate(View arg0) { }
public boolean isViewFromObject(View arg0, Object arg1) { return arg0 == ((View) arg1); }
public void restoreState(Parcelable arg0, ClassLoader arg1) { }
public Parcelable saveState() { return null; }
public void startUpdate(View arg0) { }
}
}
In list.setAdapter(listAdapter); list will be null unless instantiateItem is called first. Move your assignment of list into onCreate()
Related
I would like to change the fragment when listview item clicked under Bottom navigation activity
But I have not idea how to write the OnClickListener
Anyone can provide some hints or tell me what wrong in this program?
Here is the program
And thank you for spend the time to view my program
Thank you very much
package com.example.campus.ui.campus;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import com.example.c.MainActivity;
import com.example.c.R;
import com.example.c.database.campus.CampusData;
import com.example.c.ui.campusInformation.CampusInformationActivity;
import com.example.c.ui.campusInformation.CampusInformationFragment;
import java.util.ArrayList;
import java.util.List;
public class CampusListLayoutAdapter extends BaseAdapter {
private LayoutInflater layoutInflater;
private List<CampusData> campusList = new ArrayList<CampusData>();
private int resourceViewID;
private Context context;
private Context mContext;
static class ViewHolder{
LinearLayout llCampusCard;
TextView tvCampusName;
TextView tvCampusAddress;
ImageView ivCampusImage;
}
public CampusListLayoutAdapter(Context c, List<CampusData> campusList){
context = c;
layoutInflater = LayoutInflater.from(c);
this.campusList = campusList;
}
#Override
public int getCount() {
return campusList.size();
}
#Override
public Object getItem(int i) {
return i;
}
#Override
public long getItemId(int i) {
return i;
}
#Override
public View getView(int i, View view, ViewGroup viewGroup) {
mContext = viewGroup.getContext();
ViewHolder holder = new ViewHolder();
view = layoutInflater.inflate(R.layout.listview_campus, null);
if(view != null){
holder.tvCampusName = view.findViewById(R.id.tvCampusName);
holder.tvCampusAddress = view.findViewById(R.id.tvCampusAddress);
holder.ivCampusImage = view.findViewById(R.id.ivCampusImage);
holder.tvCampusName.setText(campusList.get(i).name);
holder.tvCampusAddress.setText(campusList.get(i).address);
String image = campusList.get(i).image;
resourceViewID = context.getResources().getIdentifier(image, "drawable", context.getPackageName());
holder.ivCampusImage.setImageResource(resourceViewID);
view.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
}
});
return view;
}else {
return null;
}
}
}
First of all, create an interface in your adapter class.
public interface Callbacks {
void onItemClick(YourObject object, int position); // arguments as per the requirement
}
change your constructor of adapter as
Callbacks callback;
public CampusListLayoutAdapter(Context c, List<CampusData> campusList, Callbacks callback){
.....
this.callback = callback;
}
Now in your onClick() use..
callback.onItemClick(yourClickedItem, position)
then pass an anonymous or simply implement interface in your activity.
adapter = new CampusListLayoutAdapter(context, list, new CampusListLayoutAdapter.Callbacks() {
#Override
public void onItemClick(Alert_bean alert, int position) {
// do what you want here in activity like changing fragment or view updates
}
});
I have a custom viewPagerAdapter in this activity, when the first launch of the activity (When the main activity starts it with the intent) the pager displays the fragments correctly, but when I rotate the device, the recipe is got from the savedInstantState, and the adapter is started, but the fragments are not displayed and the getItem method doesn't get callled!
Here's the code for the Activity:
package com.ameer.bake.activities;
import android.content.Intent;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.NavUtils;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MenuItem;
import android.view.ViewGroup;
import com.ameer.bake.Constants;
import com.ameer.bake.fragments.IngredientsFragment;
import com.ameer.bake.fragments.StepDetailsFragment;
import com.ameer.bake.fragments.StepsFragment;
import com.ameer.bake.R;
import com.ameer.bake.models.Recipe;
import com.ameer.bake.models.Step;
import com.google.gson.Gson;
import com.ogaclejapan.smarttablayout.SmartTabLayout;
public class DetailsActivity extends AppCompatActivity implements StepsFragment.StepCallback{
private Recipe recipe;
private IngredientsFragment ingredientsFragment;
private StepsFragment stepsFragment;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_details);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
if (savedInstanceState != null){
recipe = new Gson().fromJson(savedInstanceState.getString(Constants.RECIPE), Recipe.class);
setupViewPager();
} else if (getIntent().hasExtra(Constants.CURRENT_RECIPE_KEY) ) {
Gson gson = new Gson();
recipe = gson.fromJson(getIntent().getStringExtra(Constants.CURRENT_RECIPE_KEY), Recipe.class);
setTitle(recipe.getName());
setupViewPager();
}
}
#Override
public void onStepClicked(Step step) {
Intent intent = new Intent(DetailsActivity.this, StepActivity.class);
intent.putExtra(Constants.STEP_KEY, new Gson().toJson(step));
startActivity(intent);
}
private class RecipePagerAdapter extends FragmentPagerAdapter {
private static final int NUM_ITEMS = 2;
private final String[] titles = new String[]{
getString(R.string.ingredients), getString(R.string.steps)};
private RecipePagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
if (ingredientsFragment == null && stepsFragment == null) {
ingredientsFragment = new IngredientsFragment();
ingredientsFragment.setIngredients(recipe.getIngredients());
stepsFragment = new StepsFragment();
stepsFragment.setSteps(recipe.getSteps());
stepsFragment.setCallback(DetailsActivity.this);
}
}
// Returns total number of pages
#Override
public int getCount() {
return NUM_ITEMS;
}
// Returns the fragment to display for that page
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return ingredientsFragment;
case 1:
return stepsFragment;
default:
return null;
}
}
// Returns the page title for the top indicator
#Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home){
NavUtils.navigateUpFromSameTask(this);
}
return super.onOptionsItemSelected(item);
}
#Override
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putString(Constants.RECIPE, new Gson().toJson(recipe));
super.onSaveInstanceState(savedInstanceState);
}
private void setupViewPager(){
ViewPager vpPager = (ViewPager) findViewById(R.id.vpPager);
FragmentPagerAdapter pagerAdapter = new RecipePagerAdapter(getSupportFragmentManager());
vpPager.setAdapter(pagerAdapter);
SmartTabLayout viewPagerTab = (SmartTabLayout) findViewById(R.id.viewpager_tab);
viewPagerTab.setViewPager(vpPager);
}
}
Switch to a FragmentStatePagerAdapter rather than using FragmentPagerAdapter. Also use getChildFragmentManager() instead of getSupportFragmentManager()
The solution was as Pedro Varela mentioned in the comments:
"Hope this works. Add setRetainInstance(true); in onCreate of your internal fragments of the view pager "Control whether a fragment instance is retained across Activity re-creation (such as from a configuration change). This can only be used with fragments not in the back stack. If set, the fragment lifecycle will be slightly different when an activity is recreated""
Thanks
I am trying to write different functionalities for my FloatingActionButton depending on the fragment that the mainActivity is currently hosting. Yet for for reason in my onClick() method, getSupportFragmentManager().findFragmentById() returns null.
I haven't seen any examples of this question implemented with a viewpager and I am curious if there is a different approach I have to take.
MainActivity
import android.content.Intent;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.View;
public class MainActivity extends FragmentActivity {
private Adapter mAdapter;
private ViewPager mViewPager;
private static FloatingActionButton bButton;
private static String UID;
private Intent intent;
public static String getUID(){
return UID;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAdapter = new Adapter(getSupportFragmentManager());
mViewPager = (ViewPager)findViewById(R.id.vPager);
mViewPager.setAdapter(mAdapter);
intent = getIntent();
UID = intent.getStringExtra("uid");
bButton = (FloatingActionButton)findViewById(R.id.bButton);
bButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Fragment fragment = getSupportFragmentManager().findFragmentById(R.id.fragContainer);
if(fragment == null){
Log.e("TAG","FRAGMENT IS NULL!!");
}
else{
Log.e("TAG","FRAGMENT IS NOT NULL!!");
}
}
});
}
}
NewsFeedFragment
import android.os.Bundle;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.ListFragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
import com.firebase.client.Firebase;
import com.firebase.client.FirebaseError;
import com.mycompany.neighbors.R;
import com.mycompany.neighbors.SinglePost;
import java.util.ArrayList;
/**
* Created by joshua on 5/25/2016.
*/
public class NewsFeedFragment extends ListFragment implements AdapterView.OnItemClickListener{
private ListView lv;
private TextView tvUserName;
private TextView tvStatus;
private ArrayList<SinglePost> posts = new ArrayList<>();
private static final String POSTS_PATH = "MY_PATH";
private Firebase postsRef;
// private static final String FRAGMENT_POST = "post";
public void postFragment(){
Log.d("TAG", "Doing something else");
PostFragment postFragment = new PostFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction()
.replace(R.id.fragContainer,postFragment)
.addToBackStack(null)
.commit();
}
#Override
public void onViewCreated(View v, Bundle s){
lv = getListView();
lv.setOnItemClickListener(this);
}
#Override
public void onCreate(Bundle savedInstance){
super.onCreate(savedInstance);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState){
View v = inflater.inflate(R.layout.fragment_post_feed_item,parent,false);//changed
tvUserName = (TextView)v.findViewById(R.id.tvUN);
tvStatus = (TextView)v.findViewById(R.id.tvStatus);
postsRef = new Firebase(POSTS_PATH);
postsRef.addChildEventListener(new com.firebase.client.ChildEventListener() {
#Override
public void onChildAdded(com.firebase.client.DataSnapshot dataSnapshot, String s) {
SinglePost post = dataSnapshot.getValue(SinglePost.class);
post.setKey(dataSnapshot.getKey());
posts.add(0, post);
if(posts.size() > 0) {
PostAdapter adapter = new PostAdapter(posts);
setListAdapter(adapter);
}else{
Toast toast = Toast.makeText(getActivity(),"No data", Toast.LENGTH_SHORT);
toast.show();
}
}
#Override
public void onChildChanged(com.firebase.client.DataSnapshot dataSnapshot, String s) {
}
#Override
public void onChildRemoved(com.firebase.client.DataSnapshot dataSnapshot) {
}
#Override
public void onChildMoved(com.firebase.client.DataSnapshot dataSnapshot, String s) {
}
#Override
public void onCancelled(FirebaseError firebaseError) {
}
});
return v;
}
#Override
public void onListItemClick(ListView l, View v, int position, long id){
SinglePost p = ((PostAdapter) getListAdapter()).getItem(position);
}
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
}
private class PostAdapter extends ArrayAdapter<SinglePost>{
public PostAdapter(ArrayList<SinglePost> singlePost){
super(getActivity(),android.R.layout.simple_list_item_1,singlePost);
}
#Override
public View getView(int position, View convertView, ViewGroup parent){
if(convertView == null){
convertView = getActivity().getLayoutInflater().inflate(R.layout.fragment_post_feed_item,null);
}
SinglePost p = getItem(position);
TextView tvUserName = (TextView)convertView.findViewById(R.id.tvUN);
tvUserName.setText(p.getUserName());
TextView tvStatus = (TextView)convertView.findViewById(R.id.tvStatus);
tvStatus.setText(p.getStatus());
return convertView;
}
}
}
I have 2 other fragments but i'll post one as an example. Here is my adapter for the viewpager.
Adapter
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import com.mycompany.neighbors.Fragments.MapFragment;
import com.mycompany.neighbors.Fragments.NewsFeedFragment;
import com.mycompany.neighbors.Fragments.ProfileFragment;
/**
* Created by joshua on 5/25/2016.
*/
public class Adapter extends FragmentPagerAdapter {
private String Fragment[] = {"Posts" , "Map" , "Profile"};
public Adapter(FragmentManager fm){
super (fm);
}
#Override
public Fragment getItem(int position) {
switch(position){
case 0:
return new NewsFeedFragment();
case 1:
return new MapFragment();
case 2:
return new ProfileFragment();
default:
return null;
}
}
#Override
public int getCount(){return Fragment.length;}
#Override
public CharSequence getPageTitle(int position) {
return Fragment[position];
}
}
Please check below link, It has very good explanation for your problem:
http://tamsler.blogspot.in/2011/11/android-viewpager-and-fragments-part-ii.html
Or you can try below code snippet:
1.Where you add fragment in view pager or view pager adapter:
MyFragment myFragment = MyFragment.newInstance();
mPageReferenceMap.put(index, "Some Tag");
getSupportFragmentManager().beginTransaction().add(myFragment,"Some Tag").commit();
2.To get the tag for the currently visible page, you then call:
int index = mViewPager.getCurrentItem();
String tag = mPageReferenceMap.get(index);
3.and then get the fragment page:
Fragment myFragment = getSupportFragmentManager().findFragmentByTag(tag);
I'm very new to fragments and I'm attempting to load a videoView into a fragment . I have my layout files laid out correctly (as I can swipe among images just fine), but I'm unsure of how to load a videoView into a fragment. My code for my activities is as follows:
package com.example.PLS;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.VideoView;
public class CustomPagerAdapter extends PagerAdapter
{
public Object instantiateItem(View collection, int position) {
LayoutInflater inflater = (LayoutInflater) collection.getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
int resId = 0;
switch (position) {
case 0: {
resId = R.layout.page1;
break;
}
case 1: {
resId = R.layout.page2;
break;
}
case 2: {
resId = R.layout.page3;
break;
}
}
View view = inflater.inflate(resId, null);
((ViewPager) collection).addView(view, 0);
return view;
}
#Override
public void destroyItem(View arg0, int arg1, Object arg2) {
((ViewPager) arg0).removeView((View) arg2);
}
#Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == ((View) arg1);
}
#Override
public Parcelable saveState() {
return null;
}
#Override
public int getCount() {
return 3;
}
}
package com.example.PLS;
import android.app.Fragment;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.widget.VideoView;
public class MyActivity extends FragmentActivity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// Create and set adapter
CustomPagerAdapter adapter = new CustomPagerAdapter();
ViewPager myPager = (ViewPager) findViewById(R.id.customviewpager);
myPager.setAdapter(adapter);
myPager.setCurrentItem(0);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
I'm not sure where or how to place the code that tells the videoView to play a video in page1 for example. Where would I place that and how would it look?
A bit offtopic:
Are you sure, that you are using Fragments and not just Views? As far as I can see, you add and remove Views.
Or do you do something within the layout files? If so, could you provide the xml layout resources?
See can i use view pager with views (not with fragments)
For your question:
After you call addView, you could do something like to following (or add that to a button listener):
String videoUri = getVideoUriForPosition(position);
// TODO check if videoUri is not null or something
mPlayerView = (VideoView) mView.findViewById(R.id.video_player);
mPlayerView.requestFocus();
if(mPlayerView == null) {
Log.e(TAG, "Video view null");
} else {
mPlayerView.setVideoURI(Uri.parse(videoUri));
mPlayerView.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
public void onPrepared(MediaPlayer mp) {
mPlayerView.start();
});
}
i'm working on simple app , i made a viewpager of 3 views, i need to put listview in the viepager
but the listview won't showup
here's my special class for viewpager
package com.Schoolreporting.androidApp;
import java.util.ArrayList;
import android.content.Context;
import android.location.Address;
import android.os.Parcelable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.widget.Adapter;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class MyPagerAdapter extends PagerAdapter {
String Name;
// State number of pages
public int getCount() {
return 4;
}
public void setName(String Name) {
this.Name = Name;
}
// Set each screen's content
#Override
public Object instantiateItem(View container, int position) {
Context context = container.getContext();
LinearLayout layout = new LinearLayout(context);
// Add elements
TextView textItem = new TextView(context);
ListView grades=new ListView(context);
ArrayList<String>names=new ArrayList<String>();
names.add("Adel");
names.add("zetta");
names.add("Pringy");
ArrayAdapter<String> adapter=new ArrayAdapter<String> (context,android.R.layout.simple_list_item_1,names);
grades.setAdapter(adapter);
switch (position) {
case 0:
Toast.makeText(context,names.get(1),Toast.LENGTH_LONG).show();
textItem.setText(Name + "'s Grades");
grades.setAdapter(adapter);
Toast.makeText(context,names.get(1),Toast.LENGTH_LONG).show();
break;
case 1:
grades.setAdapter(adapter);
textItem.setText(Name + "'s grades");
break;
case 2:
textItem.setText( Name + "'s feedback");
break;
case 3:
textItem.setText( Name + "'s school");
break;
}
layout.addView(textItem);
((ViewPager) container).addView(layout, 0); // This is the line I
// added
return layout;
}
#Override
public void destroyItem(View arg0, int arg1, Object arg2) {
((ViewPager) arg0).removeView((View) arg2);
}
#Override
public boolean isViewFromObject(View arg0, Object arg1) {
return arg0 == ((View) arg1);
}
#Override
public Parcelable saveState() {
return null;
}
}
You can do so using the following code:
Context context;
List<View> viewList;
public MyPagerAdapter(Context context) {
this.context = context;
viewList = new ArrayList<View>();
LayoutInflater inflater = LayoutInflater.from(context);
View pg1 = inflater.inflate(R.layout.pg1_layout, null);
View pg2 = inflater.inflate(R.layout.pg2_layout, null);
View pg3 = inflater.inflate(R.layout.pg3_layout, null);
viewList.add(pg1);
viewList.add(pg2);
viewList.add(pg3);
}