In my MainActivity i have this code:
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myViewPager.setCurrentItem(1);
ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));
}
private class MyPagerAdapter extends FragmentPagerAdapter {
public MyPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int pos) {
switch(pos) {
case 2: return FirstFragment.newInstance("FirstFragment, Instance 1");
case 1: return SecondFragment.newInstance("SecondFragment, Instance 1");
case 0: return ThirdFragment.newInstance("ThirdFragment, Instance 1");
default: return ThirdFragment.newInstance("ThirdFragment, Default");
}
}
#Override
public int getCount() {
return 3;
}
}
}
The fragments are working fine and when i run MainActivity i want to open the SecondFragment first, so i tried using:
myViewPager.setCurrentItem(1);
But then i get the error "myViewPager cannot be resolved", i have tried updating SDK and adding support library, but nothing seems to help, any idea how to fix it?
You have not declared myViewPager and you also need to initialize it before myViewPager.setCurrentItem(1);.
You probably meant pager.setCurrentItem(1);
Related
I am trying to create tabs in my android activity,I have done this before,used the same type implementation for this method also
Now in my Activity class in this line final PagerAdapter adapter = new PagerAdapter(getSupportFragmentManager(), tabLayout.getTabCount());
I have an error PagerAdapter is abstract; cannot be instantiate I don't know what does that mean
Here is my Activity class code
package com.example.rimapps.icar_iisr_turmeric.view;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import com.example.rimapps.icar_iisr_turmeric.R;
public class PestsHome extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_pests_home);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText(R.string.diseases));
tabLayout.addTab(tabLayout.newTab().setText(R.string.insectpescts));
tabLayout.addTab(tabLayout.newTab().setText(R.string.bioagents));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PagerAdapter adapter = new PagerAdapter
(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(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) {
}
});
}
}
Then there is another thing in my Adapter class I cannot return my final tab "tab3" it says Required android.support.v4.app.Fragment;
but i have imported that already
here is my adapter class code
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import com.example.rimapps.icar_iisr_turmeric.view.TabFragment1;
import com.example.rimapps.icar_iisr_turmeric.view.TabFragment2;
import com.example.rimapps.icar_iisr_turmeric.view.TabFragment3;
public class PagerAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;
public PagerAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
TabFragment1 tab1 = new TabFragment1();
return tab1;
case 1:
TabFragment2 tab2 = new TabFragment2();
return tab2;
case 2:
TabFragment3 tab3 = new TabFragment3();
return tab3;
default:
return null;
}
}
#Override
public int getCount() {
return mNumOfTabs;
}
please help
Issue is, you have named you customize adapter as PagerAdapter which is also an existing API in android PagerAdapter.
So remove the import
import android.support.v4.view.PagerAdapter;
and carefully import your pageradapter package
Note : It's recommended to avoid naming your classes same as android API
i followed this article http://www.truiton.com/2015/06/android-tabs-example-fragments-viewpager/ to implement swipe view and it work nice. So now i want to add button on Tab1 and when clicked has to send data to Tab2.
I know there is the issue of using interface but honestly i don't know how to add it on these codes and work provide am completely new to the android.
so far i have tried my best on these links Communication between SlidingTabLayout tabs, How to pass data from one swipe tab to another? and How can I communicate/pass data through different Fragments with Swipe Tab? but i fail.
Any one help please to make it work on every stage , i mean from Tab1 ->Mainactivity->Tab2
thanks alot
Here are the codes after i edit the question
Fragment1
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class TabFragment1 extends Fragment implements AdapterView.OnItemSelectedListener{
Button send;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v= inflater.inflate(R.layout.tab_fragment_1, container, false);
send=(Button)v.findViewById(R.id.send);
send.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// value to be sent to the TabFragment2 on button click
String value=" My Data";
}
});
return v;
}
}
Fragment2
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class TabFragment2 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
return inflater.inflate(R.layout.tab_fragment_2, container, false);
//Display value from TabFragment1
textview.setText(value);
}
}
Interface class
public Interface FragmentCommunication
{
public void printMessage(String message);
}
MainActivity
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends AppCompatActivity implements FragmentCommunication{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("Tab 1"));
tabLayout.addTab(tabLayout.newTab().setText("Tab 2"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final PagerAdapter adapter = new PagerAdapter
(getSupportFragmentManager(), tabLayout.getTabCount());
viewPager.setAdapter(adapter);
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
tabLayout.setOnTabSelectedListener(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) {
}
});
}
public void printMessage(String message)
{
Toast.makeText(MainActivity.this,message,Toast.LENGTH_LONG).show();
}
}
Adapter Class
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
public class PagerAdapter extends FragmentStatePagerAdapter {
int mNumOfTabs;
public PagerAdapter(FragmentManager fm, int NumOfTabs) {
super(fm);
this.mNumOfTabs = NumOfTabs;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
TabFragment1 tab1 = new TabFragment1();
return tab1;
case 1:
TabFragment2 tab2 = new TabFragment2();
return tab2;
default:
return null;
}
}
#Override
public int getCount() {
return mNumOfTabs;
}
}
so after posting more code I'm answering:
Implement some FragmentCommunication for both your Fragments:
//public class TabFragment1 extends Fragment implements FragmentCommunication{
public class TabFragment2 extends Fragment implements FragmentCommunication{
//public static final String TAG="TabFragment1";
public static final String TAG="TabFragment2";
...
#Override
public void onActivityCreated (Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
if(getActivity() instanceOf MainActivity)
((MainActivity) getActivity()).registerFragmentCommunication(
TAG, this);
}
#Override
public void printMessage(String message){
Toast.makeText(getActivity(), TAG+" says: "+message,
Toast.LENGTH_SHORT).show();
}
}
note this line inside onActivityCreated:
((MainActivity) getActivity()).registerFragmentCommunication(TAG, this);
this means implemented FragmentCommunication, TAG will be unique key/name of Fragment and whole method is registration of your interface in Activity. so now you have to add registerFragmentCommunication method to your MainActivity and keep reference to passed interfaces, e.g. in HashMap:
HashMap<String, FragmentCommunication> fragmentCommunications =
new HashMap<String, FragmentCommunication>();
...
public void registerFragmentCommunication(String key, FragmentCommunication fc){
fragmentCommunications.put(key, fc);
}
so now you can access each FragmentCommunication of both fragments from your MainActivity, e.g by using method like this:
public void callFragmentCommunication(String key, String msg){
if(fragmentCommunications.get(key)!=null)
fragmentCommunications.get(key).printMessage();
}
callFragmentCommunication(TabFragment1.TAG, "hi!");
callFragmentCommunication(TabFragment2.TAG, "hi!");
method is public, so Fragments can call it simply like this:
//inside TabFragment1
if(isAdded() && getActivity()!=null &&
getActivity() instanceOf MainActivity &&
!getActivity().isFinishing())
((MainActivity) getActivity()).callFragmentCommunication(
TabFragment2.TAG, "hi!");
this will show Toast with text: "TabFragment2 says: hi!", which was called inside TabFragment1. now you may pass another kind of data as well :)
there is much more methods like communicating through FragmentStatePagerAdapter like here, passing Bundle arguments where fragments are initialized, additional feedback interfaces (e.g. returning true/false when message was passed) etc. Above is just very simplified way, good luck with improving it! :)
My application is working fine when I use getChildFragmentManager() but unfortunately, it will only work with API 17 and above. Now when I switch it over to getFragmentManager(), everything works fine except for one thing. Whenever I load my tablayout in horizontal view, both pages are empty and swiping is sluggish. Vertically it is fine and they won't be empty if I first load them vertically and then switch to horizontally, because I'm using a saved instance. I have no idea what is causing this. All I know is that as soon as I switch the code above around, it happens. Let me know what is required to find the issue and I will gladly post it. I am using the support-v13 library's FragmentPagerAdapter. I am doing this so I don't have to use support-v4's way of creating fragments. I do import the ViewPager from v4 in my tablayout fragment.
Edit:
Okay when the tablayout is created for the first time, it works fine. When called again it will be blank and sluggish. It had nothing to do with orientation.
Edit:
Tablayout code Keep in mind that this code is functional. But when I change getChildFragmentManager() to getFragmentManager() it gets sluggish and only works on first oncreate:
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v13.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class TabFragment extends Fragment {
public static TabLayout tabLayout;
public static ViewPager viewPager;
public static int int_items = 2;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View x = inflater.inflate(R.layout.tab_layout, null);
tabLayout = (TabLayout) x.findViewById(R.id.tabs);
viewPager = (ViewPager) x.findViewById(R.id.viewpager);
viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));
tabLayout.post(new Runnable() {
#Override
public void run() {
tabLayout.setupWithViewPager(viewPager);
}
});
return x;
}
class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new FragmentOne();
case 1:
return new FragmentTwo();
}
return null;
}
#Override
public int getCount() {
return int_items;
}
#Override
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "TAB1";
case 1:
return "TAB2";
}
return null;
}
}
}
I'm dealing with and Android app using an activity and 3 fragments with a ViewPager and a FragmentPagerAdapter.
The app is working correctly but I still cannot retrieve the reference of a Fragment within the Activity.
The methods findFragmentById and findFragmentbyTag always return null.
Here's my code:
FragmentPagerAdapter:
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class ViewPagerAdapter extends FragmentPagerAdapter {
final int PAGE_COUNT = 3;
public ViewPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public Fragment getItem(int position) {
switch (position) {
// Open FragmentTab1.java
case 0:
FragmentTab1 fragmenttab1 = new FragmentTab1();
return fragmenttab1;
// Open FragmentTab2.java
case 1:
FragmentTab2 fragmenttab2 = new FragmentTab2();
return fragmenttab2;
// Open FragmentTab3.java
case 2:
FragmentTab3 fragmenttab3 = new FragmentTab3();
return fragmenttab3;
}
return null;
}
}
Fragment implementation:
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.app.Fragment;
public class FragmentTab1 extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Get the view from fragmenttab1.xml
View view = inflater.inflate(R.layout.fragmenttab1, container, false);
return view;
}
#Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
}
}
And finally my activity:
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the view from activity_main.xml
setContentView(R.layout.activity_main);
// Locate the viewpager in activity_main.xml
viewPager = (ViewPager) findViewById(R.id.pager);
viewPagerAdapter = new ViewPagerAdapter(getSupportFragmentManager());
// Set the ViewPagerAdapter into ViewPager
viewPager.setAdapter(viewPagerAdapter);
}
#Override
protected void onStart()
{
super.onStart();
InitializeVariables();
viewPager.setCurrentItem(1);
Fragment fragment = (Fragment)getSupportFragmentManager().findFragmentByTag(makeFragmentName(viewPager.getId(), 0));
}
I am new to android development. I following the tutorial http://slidenerd.com/2015/07/22/android-design-support-library/ which adds same fragment to the tablayout.But I need to add 3 unique fragments to the tablayout which download data from the web server.How to do that programming????
This is the code
`
package com.example.naveen.helloworld;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
public class AppMainScreen extends AppCompatActivity {
private Toolbar mToolbar;
private TabLayout mTablayout;
private ViewPager mViewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_app_main_screen2);
mToolbar = (Toolbar) findViewById(R.id.tool_bar);
setSupportActionBar(mToolbar);
mTablayout = (TabLayout) findViewById(R.id.tab_layout);
mViewPager = (ViewPager) findViewById(R.id.view_pager);
mViewPager.setAdapter(new PagerAdapter(getSupportFragmentManager()));
mTablayout.setupWithViewPager(mViewPager);
}
class PagerAdapter extends FragmentStatePagerAdapter {
public PagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int position) {
Fragment fragment =null;
switch (position) {
case 0: return new Fragment();
case 1: return new Fragment();
}
return null;
}
#Override
public int getCount() {
return 2;
}
public CharSequence getPageTitle(int position) {
switch (position) {
case 0:
return "News Feed";
case 1:
return "Events";
default:
return "News Feed";
} } }}`
Thanx in advance.
the getItem method inside the pager adapter sets the fragment so just modify the switch case to
switch(position){
case 0:
return new NewsFragment();
case 1:
return new EventsFragment();
}
Replace NewsFragment and EventsFragment with the corresponding fragments that you need to show