Show/Hide Fragments and change the visibility attribute programmatically - android-fragments

Question

This is a 2 part problem. What I'm having is a 3 Fragment layout where the 3'rd Fragment(FragmentC) is added dynamically when the user taps a button found in another fragment. Then, after it's added the 3'rd Fragment has a button to maximize/minimize it.
UPDATE: Scrool at the end for SOLUTION
PROBLEM 1:
I'm trying to change the visibility attribute of a FrameLayout that acts as a container for the 3'rd fragment(R.id.fragment_C).
What the code is supposed to do is to generate another fragment that, originally has an XML containing android:visibility = "gone". Then, the Fragment is added when tapping a button and the visibility is suppose to change to VISIBLE.
I know this has been covered before, but after 4 hours of trying to make it work I decided to ask what I'm doing wrong.
PROBLEM 2:
After the 3'rd fragment is generated I have a minimize/maximize button that's supposed to hide the first 2 Fragments and allow the 3'rd Fragment to fill the screen.
The problem is the Views of the first 2 Fragments are not removed when using .setVisibility(View.GONE). This has been covered before as well, but I can't figure out why it doesn't work in my code.
The code so far(sorry if it's to verbose but I thought it's better to include all details for you folks):
main_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:paddingLeft="0dp"
android:paddingRight="0dp"
android:orientation="vertical"
>
<FrameLayout
android:id="#+id/fragment_A"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="#CCCCCC"
>
</FrameLayout>
<FrameLayout
android:id="#+id/fragment_B"
android:layout_width="fill_parent"
android:layout_height="300dp"
android:layout_below="#id/fragment_A"
android:layout_centerHorizontal="true"
android:layout_marginTop="15dp"
android:background="#B4B4B4"
>
</FrameLayout>
<FrameLayout
android:id="#+id/fragment_C"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="#id/fragment_B"
android:layout_centerHorizontal="true"
android:layout_marginTop="0dp"
android:background="#A3A3A3"
android:visibility="gone"
>
</FrameLayout>
</RelativeLayout>
land/main_activity.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal"
android:paddingLeft="0dp"
android:paddingRight="0dp" >
<LinearLayout
android:id="#+id/fragments_container"
android:layout_width="fill_parent"
android:layout_height="200dp"
android:baselineAligned="false" >
<FrameLayout
android:id="#+id/fragment_A"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="0.5"
android:background="#CCCCCC" >
</FrameLayout>
<FrameLayout
android:id="#id/fragment_B"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="0.5"
android:background="#B4B4B4"
>
</FrameLayout>
</LinearLayout>
<FrameLayout
android:id="#+id/fragment_C"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="#id/fragment_container"
android:layout_centerHorizontal="true"
android:layout_marginTop="0dp"
android:background="#A3A3A3"
android:visibility="gone" >
</FrameLayout>
</RelativeLayout>
MainActivity.java
package com.example.android.fragments_proto.activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import com.example.android.fragments_proto.R;
import com.example.android.fragments_proto.fragment.GMC_DateSelectionFragment;
import com.example.android.fragments_proto.fragment.GMC_ProdUnitSelectionFragment;
public class MainActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_activity);
FragmentManager fm = getSupportFragmentManager();
Fragment fragmentA = fm.findFragmentById(R.id.fragment_A);
Fragment fragmentB = fm.findFragmentById(R.id.fragment_B);
if (fragmentA == null) {
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_A, new FragmentA());
ft.commit();
}
if (fragmentB == null) {
FragmentTransaction ft = fm.beginTransaction();
ft.add(R.id.fragment_B, new FragmentB());
ft.commit();
}
}
}
Now the XML and .java files for the first Fragment.
fragment_A.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:gravity="center_horizontal"
>
<DatePicker
android:id="#+id/datePicker1"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
FragmentA.java
package com.example.android.fragments_proto.fragment;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewGroup;
import android.widget.DatePicker;
import android.widget.Toast;
import com.example.android.fragments_proto.R;
public class FragmentA extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_A, container, false);
DatePicker datePicker = (DatePicker) view.findViewById(R.id.datePicker1);
datePicker.setCalendarViewShown(true);
datePicker.setSpinnersShown(false);
datePicker.setOnTouchListener(new OnTouchListener() {
#Override
public boolean onTouch(View v, MotionEvent event) {
Activity activity = getActivity();
if (activity != null) {
Toast.makeText(activity, "You Touched ME!", Toast.LENGTH_SHORT).show();
}
return false;
}
});
return view;
}
}
Now the XML and .java files for the Fragment that contains the button that when tapped adds the content in R.id.fragment_C
fragment_B.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<LinearLayout
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="0.1"
>
<ListView
android:id="#+id/listView1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
</ListView>
</LinearLayout>
<LinearLayout
android:layout_width="fill_parent"
android:orientation="horizontal"
android:gravity="center"
android:layout_height="wrap_content">
<Button
android:id="#+id/button"
android:text="#string/btn_fragment"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>
</LinearLayout>
FragmentB.java
package com.example.android.fragments_proto.fragment;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import com.example.android.fragments_proto.R;
public class FragmentB extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragmentB, container, false);
ListView listView = (ListView) view.findViewById(R.id.listView1);
Button button = (Button) view.findViewById(R.id.button);
String[] machines = new String[] { "MachineId-001", "MachineId-002", "MachineId-003", "MachineId-004", "MachineId-005", "MachineId-006", "MachineId-007", "MachineId-008"};
listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
listView.setAdapter(new ArrayAdapter<String>(getActivity(), android.R.layout.select_dialog_multichoice, machines));
final FrameLayout frameLayout = (FrameLayout) view.findViewById(R.id.fragment_C);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Activity activity = getActivity();
if (activity != null) {
getFragmentManager().beginTransaction().replace(R.id.fragment_C, new FragmentC()).setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE).addToBackStack(null).commit();
frameLayout.setVisibility(View.VISIBLE);
}
}
});
return view;
}
}
The XML and .java files for the Fragment that's supposed to be added.
fragment_C.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<LinearLayout
android:layout_width="fill_parent"
android:orientation="horizontal"
android:gravity="center"
android:layout_height="wrap_content">
<Button
android:id="#+id/maximize_button"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Maximize Me!" />
</LinearLayout>
<TextView
android:id="#+id/text_view"
android:textIsSelectable="true"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FF33FF"
/>
</LinearLayout>
FragmentC.java
package com.example.android.fragments_proto.fragment;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import com.example.android.fragments_proto.R;
public class FragmentC extends Fragment {
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_C, container, false);
TextView textView = (TextView) view.findViewById(R.id.text_view);
final Fragment fragmentA = getFragmentManager().findFragmentById(R.id.fragment_A);
final Fragment fragmentB = getFragmentManager().findFragmentById(R.id.fragment_B);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
FragmentTransaction ft = getFragmentManager().beginTransaction();
if (fragmentA.isVisible() && fragmentB.isVisible()) {
ft.hide(fragmentA);
ft.hide(fragmentB);
fragmentA.getView().setVisibility(View.GONE);
fragmentB.getView().setVisibility(View.GONE);
button.setText("Minimize Me!");
ft.addToBackStack(null);
} else {
ft.show(fragmentA);
ft.show(fragmentB);
fragmentA.getView().setVisibility(View.VISIBLE);
fragmentB.getView().setVisibility(View.VISIBLE);
button.setText("Maximize Me!");
ft.addToBackStack(null);
}
ft.commit();
}
});
return view;
}
}
Found the problem and a solution thanks to Moesio
PROBLEM:
My error was that I was trying to find a view (in FragmentB.java) with
final FrameLayout frameLayout = (FrameLayout) view.findViewById(R.id.fragment_C);
This line was returning null so when the code reached the point where it was supposed to do a .setVisibility() then the app. would return a nullPointerException.
The same happened for FragmentC.java (so my 2 problems were related). The Views were not removed because my findViewById was null!
SOLUTION:
Just search for your View with getActivity.findViewById(R.id.your_view);

Answer 1

In FragmentB you're trying get a view which is not on your contentView
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_b, container, false);
// this is in fragment_b layout
ListView listView = (ListView) view.findViewById(R.id.listView1);
Button button = (Button) view.findViewById(R.id.button);
/* ... */
// ****************************************
// this is NOT in fragment_b layout, which causes null
// ****************************************
final FrameLayout frameLayout = (FrameLayout) view.findViewById(R.id.fragment_C);
/* ... */
}
Try:
final FrameLayout frameLayout = (FrameLayout) getActivity().getWindow().findViewById(R.id.fragment_C);
Whereas R.id.fragment_C is inflated and setted on MainActivity.
Moreover, I had the same problem until use an extra flag
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
final Fragment fragmentC = new FragmentC();
fragmentTransaction.add(R.id.fragment_C, fragmentC);
fragmentTransaction.commit();
menuIsOn = false;
final View fragmentCView = findViewById(R.id.fragment_C);
final Button btn = (Button) findViewById(R.id.btn);
btnPowers.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (!menuIsOn) {
fragmentCView.setVisibility(View.VISIBLE);
} else {
fragmentCView.setVisibility(View.INVISIBLE);
}
menuIsOn = !menuIsOn;
}
});

Answer 2

Create the Instances of fragments and add instead of replace
FragA fa= new FragA();
FragB fb= new FragB();
FragC fc= new FragB();
fragmentManager = getSupportFragmentManager();
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.fragmnt_container, fa);
fragmentTransaction.add(R.id.fragmnt_container, fb);
fragmentTransaction.add(R.id.fragmnt_container, fc);
fragmentTransaction.show(fa);
fragmentTransaction.hide(fb);
fragmentTransaction.hide(fc);
fragmentTransaction.commit();
suppose we want to to hide and show different fragments based on our action
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.hide(fa);
fragmentTransaction.show(fb);
fragmentTransaction.hide(fc);
fragmentTransaction.commit();