The problem I have is the List View does not show up on my fragment. I tried different suggestions from the internet, but it doesn't work.
Here is my code for MainMenuFragment.java
package project.foodkit.tabbed_activity;
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.lang.reflect.Array;
public class MainMenuFragment extends Fragment {
private ArrayAdapter<String> adapter;
private ListView listView;
public MainMenuFragment() {
// Required empty public constructor
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_main_menu, container, false);
//array holding data->to be changed to list data from database
String[] food = {"pizza", "burger", "chocolate", "ice-cream", "banana", "apple"};
listView = (ListView) view.findViewById(R.id.mainMenu);
adapter = new ArrayAdapter<String>(
getActivity(),
android.R.layout.simple_list_item_1,
food
);
listView.setAdapter(adapter);
// Inflate the layout for this fragment
return view;
}
and the code for fragment_main_menu.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="project.foodkit.tabbed_activity.MainMenuFragment">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/mainMenu" />
</FrameLayout>
and the mainActivity.java
public class MainActivity extends AppCompatActivity {
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {#link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
private SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
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();
}
});
}
#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_main, 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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main_menu, container, false);
return rootView;
}
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
#Override
public int getCount() {
// Show 3 total pages.
return 2;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "Shopping Cart";
case 1:
return "Existing ingredients";
}
return null;
}
}
}
Here you used PlaceholderFragement not your MainMenuFragment
#Override
public Fragment getItem(int position) {
return PlaceholderFragment.newInstance(position + 1); <-- here is the problem
}
you should use your fragment instead. like
#Override
public Fragment getItem(int position) {
return new MainMenuFragment();
}
There is no issue in setting listview inside MainMenuFragment();
You have wrong code inside SectionsPagerAdapter
replace return PlaceholderFragment.newInstance(position + 1); with return new MainMenuFragment();
remove PlaceholderFragment from MainActivity.class
Related
I am attempting to learn the basics behind Tabs in Android Studio and ALL tutorials I have currently watched go over the basics however at the very bottom of their "MainActivity" file the following code is shown:
#Override
public CharSequence getPageTitle(int position){
switch (position){
case 0:
return "SECTION 1";
case 2:
return "SECTION 2";
case 3:
return "SECTION 3";
}
return null;
}
I believe from my understanding this is a key method.
However, once I create a DEFAULT Tabbed Activity, it appears this may have been changed. Is it possible to go back to the recent versions of the default activity?
This is what my MainActivity.java file looks like currently.
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {#link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
private SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
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();
}
});
}
#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_main, 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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.section_label);
textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
}
}
As shown, I believe I may have a different version of the default activity for tabbed applications?
Can this be fixed?
Thanks everyone.
I don't see any reason to "go back" when you can just add that method back in
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public CharSequence getPageTitle(int position){
switch (position){
case 0:
return "SECTION 1";
case 1:
return "SECTION 2";
case 2:
return "SECTION 3";
}
return null;
}
Tip: Change it to return "SECTION " + (position + 1) instead.
Otherwise, I think you can set the labels during the definition of the TabLayout class
First of all, I'm a beginner in Android programming. What I'm trying to do is to program three Tabs with each a ListView inside (you know it from e.g. WhatsApp). Android Studio makes it easy to automatically create a Tabbed Activity. So the question is: how can I implement a ListView for each Tab?
Actually there is a nice tutorial on http://www.androidhive.info/2012/05/android-combining-tab-layout-and-list-view/ which uses TabActivity. However this method is deprecated and Fragments should be used instead. I have extended main_fragment.xml (which was created by Android Studio) with a ListView. But what is the correct way to set the corresponding list adapters and especially where to set them? Setting them like ListView list_all = (ListView) findViewById(R.id.listViewAll) in onCreate() does not work because of a null object reference error. Also I didn't find out how to use the rootView which is returned by onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) So how can I solve this problem?
main_fragment.xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:background="#color/colorAccent"
android:paddingTop="#dimen/activity_vertical_margin">
<ListView
android:id="#+id/listViewAll"
android:layout_width="match_parent"
android:layout_height="match_parent"></ListView>
</RelativeLayout>
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 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/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:background="#color/white"
tools:context="de.url.members">
<android.support.design.widget.AppBarLayout
android:id="#+id/appbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:paddingTop="#dimen/appbar_padding_top"
android:background="#color/bg_login_dark"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="#color/bg_login_dark"
app:layout_scrollFlags="scroll|enterAlways"
app:popupTheme="#style/AppTheme.PopupOverlay">
</android.support.v7.widget.Toolbar>
<android.support.design.widget.TabLayout
android:id="#+id/tabs"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:tabMaxWidth="0dp"
app:tabGravity="fill"
app:tabMode="fixed"
android:fillViewport="false" />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior" />
<android.support.design.widget.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end|bottom"
android:layout_margin="#dimen/fab_margin"
android:src="#android:drawable/ic_dialog_email" />
</android.support.design.widget.CoordinatorLayout>
main.java:
public class main extends AppCompatActivity {
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {#link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
private SectionsPagerAdapter mSectionsPagerAdapter;
// The {#link ViewPager} that will host the section contents.
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
// action here
}
});
}
#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_members, 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.logout) {
//action here
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
int sectionNumber = getArguments().getInt(ARG_SECTION_NUMBER);//INDEX of selected TAB
View rootView;
if (sectionNumber == 1){
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}else if (sectionNumber == 2){
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}else if (sectionNumber == 3){
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}else{
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}
return rootView;
}
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return getResources().getString(R.string.title_section1);
case 1:
return getResources().getString(R.string.title_section2);
case 2:
return getResources().getString(R.string.title_section3);
}
return null;
}
}
}
If you want to use Listing with tablayout and viewpager try this way it will work for you
public class MainActivity extends AppCompatActivity {
private static Toolbar toolbar;
private static ViewPager viewPager;
private static TabLayout tabLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
viewPager = (ViewPager) findViewById(R.id.viewPager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabLayout);
tabLayout.setupWithViewPager(viewPager);//setting tab over viewpager
//Implementing tab selected listener over tablayout
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setCurrentItem(tab.getPosition());//setting current selected item over viewpager
switch (tab.getPosition()) {
case 0:
Log.e("TAG","TAB1");
break;
case 1:
Log.e("TAG","TAB2");
break;
case 2:
Log.e("TAG","TAB3");
break;
}
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
}
//Setting View Pager
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new DummyFragment("ANDROID"), "ANDROID");
adapter.addFrag(new DummyFragment("iOS"), "iOS");
adapter.addFrag(new DummyFragment("WINDOWS"), "WINDOWS");
viewPager.setAdapter(adapter);
}
//View Pager fragments setting adapter class
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<>();//fragment arraylist
private final List<String> mFragmentTitleList = new ArrayList<>();//title arraylist
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
//adding fragments and title method
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
return mFragmentTitleList.get(position);
}
}
}
For more see android-material-design-tabs-using-tablayout
OR
Check this http://www.tutorialsbuzz.com/2015/10/Android-Sliding-TabLayout-ListView-WhatsApp.html
And check this https://github.com/codepath/android_guides/wiki/Handling-Scrolls-with-CoordinatorLayout
OUTPUT
I will explain what you have to do to put a ListView on one of the fragments. (Sorry if I write a bad English)
You should put your listView view on the xml witch is displayed by one of your fragments. In the code that you have post the layout witch fragment displays is R.layout.main_fragment
Then on the fragment you have to declare your ListView:
ListView list_all = (ListView) rootView.findViewById(R.id.listViewAll);
You have to create a ListView adapter, an object class and some other files, you can use the tutorial witch you have post.
Link
Then write your code to set an Adapter to this ListView after the rootView is assigned on the fragment:
if (sectionNumber == 1){
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}else if (sectionNumber == 2){
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}else if (sectionNumber == 3){
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}else{
rootView = inflater.inflate(R.layout.main_fragment, container, false);
}
ArrayList<Object> arrayListOfObjects = new ArrayList<>();
arrayListOfObjects.add(new Object(...));
MyAdapter adapter = new MyAdapter(arrayListOfObjects);
list_all.setListAdapter(adapter);
I have solved it now by simply editing the getItem() method of public class SectionsPagerAdapter in main.java.
Just return a default ListFragment instead of the PlaceholderFragment.
Interesting note: Returning the same ListFragment object for all tabs leads to an error.
main.java:
public class MainActivity extends AppCompatActivity {
private ArrayAdapter<String> adapter;
private ListFragment contacts1 = new ListFragment();
private ListFragment contacts2 = new ListFragment();
private ListFragment contacts3 = new ListFragment();
List<String> words = new ArrayList<String>();
private SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
words.add("Hello");
words.add("World");
words.add("!");
adapter = new ArrayAdapter<String>(this,R.layout.item,words);
contacts1.setListAdapter(adapter);
contacts2.setListAdapter(adapter);
contacts3.setListAdapter(adapter);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
Snackbar.make(view, "Update List", Snackbar.LENGTH_LONG).setAction("Action", null).show();
words.add("New Item");
adapter.notifyDataSetInvalidated();
}
});
}
#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_main, 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);
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public ListFragment getItem(int position) {
if (position == 0){
return contacts1;
}else if (position == 1){
return contacts2;
}else{
return contacts3;
}
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "SECTION 1";
case 1:
return "SECTION 2";
case 2:
return "SECTION 3";
}
return null;
}
}
}
I'm a beginner. I am having a problem with Spinner. I'm using tabbed activity with fragments. When I add spinner in fragment main and add listener to it and when I run the app, it crashes, saying
( java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Spinner.setOnItemSelectedListener(android.widget.AdapterView$OnItemSelectedListener)' on a null object reference)
I've checked everything and seems fine. I don't know what is the matter, please guys help me out. I really need to fix this bug, my Android Studio version is 2.1.2
MainActivity.java
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
spinner = (Spinner)findViewById(R.id.spin);
spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(MainActivity.this, parent.getItemAtPosition(position).toString(), Toast.LENGTH_SHORT).show();
}
#Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
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();
}
});
}
#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_main, 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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
TextView textView = (TextView) rootView.findViewById(R.id.section_label);
textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
return rootView;
}
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class below).
return PlaceholderFragment.newInstance(position + 1);
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "SECTION 1";
case 1:
return "SECTION 2";
case 2:
return "SECTION 3";
}
return null;
}
}
}
I set up a fragment which looks like this:
The EditText("5") has the id et_input. Now I want to interact with my EditText but it doesn't work.
MainActivity.java
public class MainActivity extends AppCompatActivity {
/**
* The {#link android.support.v4.view.PagerAdapter} that will provide
* fragments for each of the sections. We use a
* {#link FragmentPagerAdapter} derivative, which will keep every
* loaded fragment in memory. If this becomes too memory intensive, it
* may be best to switch to a
* {#link android.support.v4.app.FragmentStatePagerAdapter}.
*/
private SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
getSupportActionBar().hide();
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
public PlaceholderFragment() {
}
/**
* Returns a new instance of this fragment for the given section
* number.
*/
public static PlaceholderFragment newInstance(int sectionNumber) {
PlaceholderFragment fragment = new PlaceholderFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
switch (getArguments().getInt(ARG_SECTION_NUMBER) - 1) {
case 1:
return inflater.inflate(R.layout.fragment_roman_numbers, container, false);
case 2:
return inflater.inflate(R.layout.fragment_binary_numbers, container, false);
default:
return inflater.inflate(R.layout.fragment_main, container, false);
}
}
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
if(position == 0) {
return main.newInstance();
} else if(position == 1) {
return roman_numbers.newInstance();
} else if(position == 2) {
return binary_numbers.newInstance();
}
throw new IllegalArgumentException("There is no fragment for position [" + position + "]");
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return getString(R.string.fragment_home);
case 1:
return getString(R.string.fragment_roman_numbers);
case 2:
return getString(R.string.fragment_binary_numbers);
}
return null;
}
}
}
binary_numbers.java
public class binary_numbers extends Fragment {
public binary_numbers() {
// Required empty public constructor
}
public static binary_numbers newInstance() {
binary_numbers fragment = new binary_numbers();
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_binary_numbers, container, false);
EditText et_input = (EditText) view.findViewById(R.id.et_input);
et_input.setText("TEST");
// Inflate the layout for this fragment
return view;
}
}
roman_numbers.java and main.java look exactly the same except for binary_numbers being replaced with their names.
fragement_binary_numbers.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.ngtnttnmnt.xtool.MainActivity$PlaceholderFragment">
<EditText
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:inputType="number"
android:ems="10"
android:id="#+id/et_input"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="100dp"
android:hint="#string/input_hint"
android:gravity="center" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
android:id="#+id/tv_output"
android:layout_centerVertical="true"
android:layout_centerHorizontal="true"
android:textSize="40dp"
android:gravity="center" />
fragement_roman_numbers.xml looks exactly the same and fragement_main.xml has two TextView's
Should be
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_binary_numbers, container, false);
EditText et_input = (EditText) view.findViewById(R.id.et_input);
et_input.setText("TEST");
// Inflate the layout for this fragment
return view;
}
EDIT:
As I said, you're showing a different fragment. In reality, you are showing the PlaceholderFragment created within your SectionsPagerAdapter, which just selects the binary_number layout when it's inflated, but you're not actually showing a binary_numbers fragment.
Your code should be the following:
public class MainActivity extends AppCompatActivity {
private SectionsPagerAdapter mSectionsPagerAdapter;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.container);
mViewPager.setAdapter(mSectionsPagerAdapter);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(mViewPager);
getSupportActionBar().hide();
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
if(position == 0) {
return home.newInstance();
} else if(position == 1) {
return roman_numbers.newInstance();
} else if(position == 2) {
return binary_numbers.newInstance();
}
throw new IllegalArgumentException("There is no fragment for position [" + position + "]");
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return getString(R.string.fragment_home);
case 1:
return getString(R.string.fragment_roman_numbers);
case 2:
return getString(R.string.fragment_binary_numbers);
}
throw new IllegalArgumentException("There is no fragment for position [" + position + "]");
}
}
}
Please note the complete removal of the PlaceholderFragment class, because you won't need it, ever.
EDIT: also add
public class home extends Fragment {
public static home newInstance() {
return new home();
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle saveInstanceState) {
return inflater.inflate(R.layout.fragment_main, container, false);
}
}
EDIT:
Also modify your binary_numbers class like so
import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.InputFilter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import com.ngtnttnmnt.xtool.InputFilterMinMax;
import com.ngtnttnmnt.xtool.R;
public class binary_numbers extends Fragment {
public binary_numbers() {
// Required empty public constructor
}
public static binary_numbers newInstance() {
binary_numbers fragment = new binary_numbers();
return fragment;
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_binary_numbers, container, false);
EditText et_input = (EditText) view.findViewById(R.id.et_input);
et_input.setText("TEST");
// Inflate the layout for this fragment
return view;
}
}
public class SectionsPagerAdapter extends FragmentPagerAdapter {
private PlaceholderFragment mPlaceholderFragment;
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
if(mPlaceholderFragment == null){
mPlaceholderFragment = PlaceholderFragment.newInstance(position + 1);
}
return mPlaceholderFragment;
}
It should be like this
I have a ListView within a ListFragment, and currently I just want a click on any of the items to go to ProblemActivity.class, which is currently a barebones 'HelloWorld' activity. Problem is I don't think the onItemClickListener is firing, and I'm not sure why, as I'm an Android novice. Any ideas?
public class MainActivity extends Activity implements ActionBar.TabListener {
SectionsPagerAdapter mSectionsPagerAdapter;
/**
* The {#link ViewPager} that will host the section contents.
*/
ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set up the action bar.
final ActionBar actionBar = getActionBar();
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Create the adapter that will return a fragment for each of the three
// primary sections of the activity.
mSectionsPagerAdapter = new SectionsPagerAdapter(getFragmentManager());
// Set up the ViewPager with the sections adapter.
mViewPager = (ViewPager) findViewById(R.id.pager);
mViewPager.setAdapter(mSectionsPagerAdapter);
// When swiping between different sections, select the corresponding
// tab. We can also use ActionBar.Tab#select() to do this if we have
// a reference to the Tab.
mViewPager
.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
#Override
public void onPageSelected(int position) {
actionBar.setSelectedNavigationItem(position);
}
});
// For each of the sections in the app, add a tab to the action bar.
for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
// Create a tab with text corresponding to the page title defined by
// the adapter. Also specify this Activity object, which implements
// the TabListener interface, as the callback (listener) for when
// this tab is selected.
actionBar.addTab(actionBar.newTab()
.setText(mSectionsPagerAdapter.getPageTitle(i))
.setTabListener(this));
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void onTabSelected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
// When the given tab is selected, switch to the corresponding page in
// the ViewPager.
mViewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
#Override
public void onTabReselected(ActionBar.Tab tab,
FragmentTransaction fragmentTransaction) {
}
/**
* A {#link FragmentPagerAdapter} that returns a fragment corresponding to
* one of the sections/tabs/pages.
*/
public class SectionsPagerAdapter extends FragmentPagerAdapter {
public SectionsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
// getItem is called to instantiate the fragment for the given page.
// Return a PlaceholderFragment (defined as a static inner class
// below).
switch (position) {
case 0:
return MainFragment.newInstance(position);
case 1:
return ProfileFragment.newInstance(position);
case 2:
return ReferenceFragment.newInstance(position);
default:
return MainFragment.newInstance(position);
}
}
#Override
public int getCount() {
// Show 3 total pages.
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
Locale l = Locale.getDefault();
switch (position) {
case 0:
return getString(R.string.title_section1).toUpperCase(l);
case 1:
return getString(R.string.title_section2).toUpperCase(l);
case 2:
return getString(R.string.title_section3).toUpperCase(l);
}
return null;
}
}
/**
* The default fragment containing a list view of problems.
*/
public static class MainFragment extends ListFragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section number.
*/
public static MainFragment newInstance(int sectionNumber) {
MainFragment fragment = new MainFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public MainFragment() {
}
static final String[] PROBLEMS = new String[] { "Problem 1", "Problem 2", "Probelm 3",
"Problem 4", "Problem 5", "Problem 6", "Problem 7", "Problem 8",
"Problem 9" };
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
/*TextView textView = (TextView) rootView
.findViewById(R.id.section_label);
textView.setText(Integer.toString(getArguments().getInt(
ARG_SECTION_NUMBER)));*/
setListAdapter(new ArrayAdapter<String>(getActivity(), R.layout.list_probs,PROBLEMS));
ListView listView = (ListView) rootView
.findViewById(android.R.id.list);
listView.setTextFilterEnabled(true);
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> a, View v, int position,
long id) {
Intent intent = new Intent(MainFragment.this.getActivity(), ProblemActivity.class);
startActivity(intent);
}
});
return rootView;
}
}
/**
* The profile fragment. To be completed later.
*/
public static class ProfileFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section number.
*/
public static ProfileFragment newInstance(int sectionNumber) {
ProfileFragment fragment = new ProfileFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public ProfileFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_profile, container,
false);
TextView textView = (TextView) rootView
.findViewById(R.id.section_label);
textView.setText(Integer.toString(getArguments().getInt(
ARG_SECTION_NUMBER)));
return rootView;
}
}
/**
* The reference fragment. To be completed later.
*/
public static class ReferenceFragment extends Fragment {
/**
* The fragment argument representing the section number for this
* fragment.
*/
private static final String ARG_SECTION_NUMBER = "section_number";
/**
* Returns a new instance of this fragment for the given section number.
*/
public static ReferenceFragment newInstance(int sectionNumber) {
ReferenceFragment fragment = new ReferenceFragment();
Bundle args = new Bundle();
args.putInt(ARG_SECTION_NUMBER, sectionNumber);
fragment.setArguments(args);
return fragment;
}
public ReferenceFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_reference, container,
false);
TextView textView = (TextView) rootView
.findViewById(R.id.section_label);
textView.setText(Integer.toString(getArguments().getInt(
ARG_SECTION_NUMBER)));
return rootView;
}
}
}
list_probs.xml:
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:padding="10dp"
android:textSize="20sp" >
</TextView>
Try this..
Change this..
ListView listView = (ListView) rootView.findViewById(android.R.id.list);
to
ListView listView = getListView();
EDIT
Add below code after onCreateView
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
setListAdapter(new ArrayAdapter<String>(getActivity(), R.layout.list_probs,PROBLEMS));
ListView listView = getListView();
listView.setTextFilterEnabled(true);
listView.setOnItemClickListener(new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> a, View v, int position,
long id) {
Intent intent = new Intent(MainFragment.this.getActivity(), ProblemActivity.class);
startActivity(intent);
}
});
}
Apart for the other answer you directly add ListItem click event like
#Override
public void onListItemClick(ListView l, View v, int position, long id) {
Toast.makeText(getActivity(), PROBLEMS[(int) id],Toast.LENGTH_SHORT).show();
}
For example go to
DemonstrationofusingListFragmenttoshowalistofitemsfromacannedarray.
android-custom-adapter-listview-with-listfragment-and-loadermanager-inside-fragmentactivity
try this,
Add this property in your adapter layout android:descendantFocusability="blocksDescendants" listener of Listview starts working.