Develop Reference

Why the fragment only shows on create and after tab switch?

So, in the current state, I can see the fragment inside, showing when I boot up the virtual phone; however, as soon as I switch to different fragment, from my drawer, and switch back again into the fragment, with the tableLayout, its shows nothing! Plus, switching between the tabs does seem to fix it.
You can see the image here
Here is the code:
package com.example.teamapp;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.viewpager.widget.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.material.tabs.TabItem;
import com.google.android.material.tabs.TabLayout;
public class HomeFragmentNav extends Fragment {
FragmentManager fragmentManagerHome;
ViewPager viewPager;
TabLayout tableLayout;
PagerAdapter pagerAdapter;
TabItem TeamsTab;
TabItem ChatTab;
View v;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
v = inflater.inflate(R.layout.fragment_home_nav, container, false);
tableLayout = v.findViewById(R.id.TabBar);
TeamsTab = v.findViewById(R.id.TeamsTab);
ChatTab = v.findViewById(R.id.ChatTab);
viewPager = v.findViewById(R.id.ViewPager);
tableLayout.getTabAt(1).select();
tableLayout.getTabAt(0).select();
fragmentManagerHome = getFragmentManager();
pagerAdapter = new PagerAdapter(fragmentManagerHome,
tableLayout.getTabCount(), getContext());
viewPager.setAdapter(pagerAdapter);
tableLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.setAdapter(pagerAdapter);
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});
return v;
}
#Override
public void onResume() {
super.onResume();
tableLayout = v.findViewById(R.id.TabBar);
TeamsTab = v.findViewById(R.id.TeamsTab);
ChatTab = v.findViewById(R.id.ChatTab);
viewPager = v.findViewById(R.id.ViewPager);
tableLayout.getTabAt(1).select();
tableLayout.getTabAt(0).select();
fragmentManagerHome = getFragmentManager();
pagerAdapter = new PagerAdapter(fragmentManagerHome,
tableLayout.getTabCount(), getContext());
viewPager.setAdapter(pagerAdapter);
}
}
Thank you for your help.

Prevent the page from refreshing.
view_pager.setOffscreenPageLimit(2);

Found the problem, I used getFragmentManager() instead of getChildFragmentManager()

Destroy FragmentStatePagerAdapter instance with parent Fragment

I am not sure how to ask this. I tried in here, but I guess I was not clear enough. So, I thought I just write a small App to describe the situation. Please note, the App uses Googles SlidingTabLayout.
Long story short, at any point if I click Button1, the FrameLayout should contain Fragment1, removing Fragment2 (if exists). Therefore, FragmentViewPager should also be destroyed as Fragment2. However, even then if I change the orientation of my device, I get the Toast which is defined in the onCreate() method of FragmentViewPager.
Why FragmentViewPager's onCreate is called even if Fragment2 is paused/destroyed? Is it possible that, the Toast of FragmentViewPager will not be shown when Fragment2 is destroyed?
MainActivity:
package com.abdfahim.testproject;
import android.app.Fragment;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button1 = (Button) findViewById(R.id.button1);
button1.setOnClickListener(onClickListener);
Button button2 = (Button) findViewById(R.id.button2);
button2.setOnClickListener(onClickListener);
}
private View.OnClickListener onClickListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
Fragment fragment;
switch (v.getId()){
case R.id.button1:
fragment = new Fragment1();
break;
case R.id.button2:
fragment = new Fragment2();
break;
default:
return;
}
getFragmentManager().beginTransaction().replace(R.id.frame_container, fragment, v.getTag().toString()).addToBackStack(null).commit();
}
};
}
Fragment1
package com.abdfahim.testproject;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class Fragment1 extends Fragment {
public Fragment1(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment1,container,false);
setHasOptionsMenu(true);
return rootView;
}
}
Fragment2
package com.abdfahim.testproject;
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.v13.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class Fragment2 extends Fragment {
public Fragment2(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment2,container,false);
setHasOptionsMenu(true);
CharSequence titles[]= {"Tab A", "Tab B"};
// Creating The ViewPagerAdapter
ViewPagerAdapter adapter = new ViewPagerAdapter(getActivity().getFragmentManager(), titles, titles.length);
ViewPager pager = (ViewPager) rootView.findViewById(R.id.pager);
pager.setAdapter(adapter);
// Assigning the Sliding Tab Layout View
SlidingTabLayout tabs = (SlidingTabLayout) rootView.findViewById(R.id.tabs);
// Setting the ViewPager For the SlidingTabsLayout
tabs.setViewPager(pager);
return rootView;
}
static class ViewPagerAdapter extends FragmentStatePagerAdapter {
private CharSequence titles[];
private int numbOfTabs;
public ViewPagerAdapter(FragmentManager fm, CharSequence mTitles[], int mNumbOfTabs) {
super(fm);
this.titles = mTitles;
this.numbOfTabs = mNumbOfTabs;
}
#Override
public int getItemPosition(Object object) {
return POSITION_NONE;
}
#Override
public Fragment getItem(int position) {
Bundle bundle = new Bundle();
bundle.putString("displayText", "Inside Fragment 2, " + titles[position]);
FragmentViewPager fragment = new FragmentViewPager();
fragment.setArguments(bundle);
return fragment;
}
// This method return the titles for the Tabs in the Tab Strip
#Override
public CharSequence getPageTitle(int position) {
return titles[position];
}
// This method return the Number of tabs for the tabs Strip
#Override
public int getCount() {
return numbOfTabs;
}
}
}
FragmentViewPager
package com.abdfahim.testproject;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
public class FragmentViewPager extends Fragment {
public FragmentViewPager(){}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_view_pager,container,false);
setHasOptionsMenu(true);
Bundle bundle = this.getArguments();
TextView textView = (TextView) rootView.findViewById(R.id.tabText);
textView.setText(bundle.getString("displayText"));
return rootView;
}
#Override
public void onStart() {
super.onStart();
Toast.makeText(getActivity(), "This is View Pager Fragment", Toast.LENGTH_SHORT).show();
}
}

when you use fragment inside another fragment. you use getChildFragmentManager() instead of getFragmentManager. You can call setAdapter() for the ViewPager from onCreateView() or onActivityCreated()
for more detail. have a look at it
Why it is not possible to use ViewPager within a Fragment? It actually is

For every click your OnClickListener creates the instance of Fragment2 and does not create Fragment1. That is due to the misuse of View#getTag.
In MainActivity#onCreate, change the if in the definition of onClickListener to this(using this answer):
switch (v.getId()){
case R.id.button1:
fragment = new Fragment1();
break;
case R.id.button2:
fragment = new Fragment2();
break;
default:
return;
}
In your code, in the if that is checked upon a click (for example after clicking button1) android asks v (the clicked View) for its tag - but as none was set using View#setTag - it returns null which is of course not equal to the String object created for "button1", thus the if reverts to the else every time.

Android: Detect single fragment viewpager with Tab

I have a problem with android a ViewPager setup with FragmentPagerAdapter and TabLayout
TabLayout works fine. But, the code in all tabs run simultaneously. I want the code in the currently selected tab to run
This is my activity
package francesco.prisco.siamostudenti.ui;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
import francesco.prisco.siamostudenti.R;
import francesco.prisco.siamostudenti.ui.fragments.CalendarFragment;
import francesco.prisco.siamostudenti.ui.fragments.ChatFragment;
import francesco.prisco.siamostudenti.ui.fragments.EmailFragment;
import francesco.prisco.siamostudenti.ui.fragments.HomeFragment;
import francesco.prisco.siamostudenti.ui.fragments.ProfiloFragment;
public class HomeTabActivity extends AppCompatActivity {
// private Toolbar toolbar;
private TabLayout tabLayout;
private ViewPager viewPager;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home_tab);
// toolbar = (Toolbar) findViewById(R.id.toolbar);
// setSupportActionBar(toolbar);
// getSupportActionBar().setDisplayHomeAsUpEnabled(true);
viewPager = (ViewPager) findViewById(R.id.viewpager);
setupViewPager(viewPager);
tabLayout = (TabLayout) findViewById(R.id.tabs);
tabLayout.setupWithViewPager(viewPager);
setupTabIcons();
}
private void setupTabIcons() {
int[] tabIcons = {
R.drawable.ic_home,
R.drawable.ic_calendar,
R.drawable.ic_chat,
R.drawable.ic_email,
R.drawable.ic_profile
};
tabLayout.getTabAt(0).setIcon(tabIcons[0]);
tabLayout.getTabAt(1).setIcon(tabIcons[1]);
tabLayout.getTabAt(2).setIcon(tabIcons[2]);
tabLayout.getTabAt(3).setIcon(tabIcons[3]);
tabLayout.getTabAt(4).setIcon(tabIcons[4]);
}
private void setupViewPager(ViewPager viewPager) {
ViewPagerAdapter adapter = new ViewPagerAdapter(getSupportFragmentManager());
adapter.addFrag(new HomeFragment(), "HOME");
adapter.addFrag(new CalendarFragment(), "CALENDAR");
adapter.addFrag(new ChatFragment(), "CHAT");
adapter.addFrag(new EmailFragment(), "EMAIL");
adapter.addFrag(new ProfiloFragment(), "PROFILO");
viewPager.setAdapter(adapter);
}
class ViewPagerAdapter extends FragmentPagerAdapter {
private final List<Fragment> mFragmentList = new ArrayList<();
private final List<String> mFragmentTitleList = new ArrayList<>();
public ViewPagerAdapter(FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
return mFragmentList.get(position);
}
#Override
public int getCount() {
return mFragmentList.size();
}
public void addFrag(Fragment fragment, String title) {
mFragmentList.add(fragment);
mFragmentTitleList.add(title);
}
#Override
public CharSequence getPageTitle(int position) {
// return null to display only the icon
return null;
}
}
}
And this is code of a fragment
package francesco.prisco.siamostudenti.ui.fragments;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;
import francesco.prisco.siamostudenti.R;
import francesco.prisco.siamostudenti.ui.HomeTabActivity;
public class ProfiloFragment extends Fragment {
public ProfiloFragment() {}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_profilo, container, false);
return rootView;
}
}
Help me please

Like #Mrugesh Thaker says, all of the Fragment lifecycle functions - onCreateView(), etc. are executed every time the View of a Fragment is inflated.
Here, the View of each Fragment is inflated every time it becomes the adjacent Fragment of the current Fragment page.
So, you should move the 'code each Fragment needs to execute' when it becomes the currently selected Fragment page into an OnPageChangeListener
In your HomeTabActivity, when you set up the ViewPager, add an
OnPageChangeListener to yourViewPager
private void setupViewPager(ViewPager viewPager) {
.
.
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener(){
public void onPageScrollStateChanged (int state){
}
public void onPageSelected (int position){
/*
* Define the action to be performed for each page.
* Variable 'position' is the index of the page in the ViewPager
*/
}
public void onPageScrolled (int position, float positionOffset, int positionOffsetPixels){
}
});
}
Learning Resource

Actually, view pager works like that. The main aim of view pager is to enable a user to have smooth swipe , so what it does is , it will create all the fragments that you gave at a time to have smooth swiping flow. This is actually the limitation of it because all the methods of fragment lifecycle are called at a time.

Android: How to REPLACE or OVERLAY fragments when a FragmentPagerAdapter is used

I have an app with three tabs which I control with an FragmentPagerAdapter. Now I want to jump between those tabs when I click on a TextView of one fragment (the fragment with the TextView should be replaced with the destination fragment). And when i click on a Button another Fragment should be overlayed above this fragment with the Button.
I know that those are two different things but I also know that I have to use FragmentTransaction but I can't figure out how to do it.
Could you please help me?
Here is my MainActivy.java:
package letscho.workout;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.support.design.widget.TabLayout;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
public class MainActivity extends AppCompatActivity {
Toolbar toolbar;
ViewPager viewPager;
TabLayout tabLayout;
FragmentManager fragmanager;
FragmentTransaction fragtrans;
Fragment1 fragment1;
#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);
ViewPagerAdapter1 viewPagerAdapter1 = new ViewPagerAdapter1(getSupportFragmentManager());
viewPager.setAdapter(viewPagerAdapter1);
tabLayout = (TabLayout) findViewById(R.id.tablayout);
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
tabLayout.setupWithViewPager(viewPager);
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 static void changefragmentOnBtnClick(){
fragmanager = getFragmentManager();
fragtrans = fragmanager.beginTransaction();
fragtrans.replace(R.id.viewpager, getActivity());
fragtrans.commit();
}
}
And the ViewPager:
package letscho.workout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class ViewPagerAdapter1 extends FragmentPagerAdapter {
String [] tabtitlearray = {"Übungen", "Push", "Pull"};
public ViewPagerAdapter1 (FragmentManager manager) {
super(manager);
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0: return new Fragment1();
case 1: return new Fragment2();
case 2: return new Fragment3();
}
return null;
}
#Override
public int getCount() {
return 3;
}
#Override
public CharSequence getPageTitle(int position) {
return tabtitlearray[position];
}
}
And the Fragment where all should start:
package letscho.workout;
import android.content.Context;
import android.content.SharedPreferences;
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.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Fragment2 extends Fragment {
View contentView2;
TextView textView;
Button btn1;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
contentView2 = inflater.inflate(R.layout.layout2_push, null);
return contentView2;
}
#Override
public void onViewCreated(View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
textView = (TextView)contentView2.findViewById(R.id.push_text_eins);
textView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
MainActivity.changefragmentOnBtnClick();
}
});
btn1 = (Button) contentView2.findViewById(R.id.btn_timer1);
btn1.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
}
});
}
#Override
public void onStop() {
super.onStop();
}
}

How to go back to the parent Fragment using webview?

I have used fragments here. But I cannot go back to the parent.
Swipeactivitydefault.java
package com.pokhara.nepal;
import android.app.ActionBar;
import android.app.ActionBar.Tab;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import com.pokhara.nepal.json.TabsPagerAdapter;
public class Swipeactivitydefault extends FragmentActivity implements
ActionBar.TabListener {
private ViewPager viewPager;
private TabsPagerAdapter mAdapter;
private ActionBar actionBar;
// Tab titles
private String[] tabs = { "Tab1", "Tab2", "Tab3" };
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.viewpager_news);
// Initilization
viewPager = (ViewPager) findViewById(R.id.pager);
actionBar = getActionBar();
mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
viewPager.setAdapter(mAdapter);
actionBar.setHomeButtonEnabled(false);
actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
// Adding Tabs
for (String tab_name : tabs) {
actionBar.addTab(actionBar.newTab().setText(tab_name)
.setTabListener(this));
}
/**
* on swiping the viewpager make respective tab selected
* */
viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
#Override
public void onPageSelected(int position) {
// on changing the page
// make respected tab selected
actionBar.setSelectedNavigationItem(position);
}
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
}
#Override
public void onTabReselected(Tab tab, FragmentTransaction ft) {
}
#Override
public void onTabSelected(Tab tab, FragmentTransaction ft) {
// on tab selected
// show respected fragment view
viewPager.setCurrentItem(tab.getPosition());
}
#Override
public void onTabUnselected(Tab tab, FragmentTransaction ft) {
}
}
Tab1.java
package com.pokhara.nepal;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.widget.LinearLayout;
public class Tab1 extends Fragment {
private WebView webView;
private Bundle webViewBundle;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout ll = (LinearLayout) inflater.inflate(
R.layout.news_activity_child, container, false);
webView = (WebView) ll.findViewById(R.id.webview);
webView.getSettings().setSupportZoom(true);
webView.getSettings().setBuiltInZoomControls(true);
WebSettings webSettings = webView.getSettings();
webSettings.setJavaScriptEnabled(true);
webView.setWebViewClient(new MyCustomWebViewClient());
if (webViewBundle == null) {
webView.loadUrl("http://www.tipfortechs.com/mobile");
} else {
webView.restoreState(webViewBundle);
}
webView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
return ll;
}
}
Tab2.java and Tab3.java are also same as Tab 1
Just wanted to make three tabs.
TabsPagerAdapter.java
package com.pokhara.nepal.json;
import android.app.Activity;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import com.pokhara.nepal.Ekantipur;
import com.pokhara.nepal.HimalayaTimes;
import com.pokhara.nepal.NepalNews;
public class TabsPagerAdapter extends FragmentPagerAdapter {
public TabsPagerAdapter(FragmentManager fm) {
super(fm);
}
#Override
public Fragment getItem(int index) {
switch (index) {
case 0:
// Top Rated fragment activity
return new Tab1();
case 1:
// Games fragment activity
return new Tab2();
case 2:
// Movies fragment activity
return new Tab3();
}
return null;
}
#Override
public int getCount() {
// get item count - equal to number of tabs
return 3;
}
}
news_activity_child.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<WebView
android:id="#+id/webview"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
Help me Please!!! I want to go back to the parent fragment after opening the link from that webview.
I know there are many answer out there. The one was overiding the back button. But I donot know how to implement. I am new to this. So, can somebody help me with the code.

#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//...
}
#Override
public void onBackPressed() {
this.getParent().onBackPressed();
}
write onBackPressed() override method on tab1/tab2/tab3 fragment pages. It will help you.

I am unfamiliar with webview but I have worked with tabbed fragments.
From my experience with tabbed fragments, one way to go would be to implement a method on the main activity that "exposes your viewpager functionality" and swtiches to a desired fragment. For example:
public void showTab(int n) {
viewPager.setCurrentItem(n);
}
Then, within the fragment you want to trigger the transition to the other fragment, you just get the reference to the acitivy and tell it to show the tab you want.
Swipeactivitydefault m = (Swipeactivitydefault )getActivity();
m.showTab(1);