So I am still fairly new to working with Android Studio and everything in it. I have been stuck on trying to get fragments to communicate directly with each other. Here I'm simply just trying to set the TextView text element within one of my fragments. I have looked for hours and tried a lot, but I'm not sure what to do. Also, I am implementing my fragments through code in a FrameLayout.
Here is my fragment whose text value I'm trying to edit:
public class ReceivingFrag extends Fragment {
TextView sender;
public void updateText(String text) {
sender.setText(text);
}
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.frag_sender, container, false);
sender = (TextView) v.findViewById(R.id.sender);
return v;
}
}
I believe my root problem is that getView() and sender both return Null. I also understand that fragments are not technically views, but rather aid in the layout of views and ViewGroups. Any help is appreciated.
Not sure if it helps, but this is the method that calls the updateText() method within the ReceivingFrag class.
public void sendText(String text){
ReceivingFrag frag = new ReceivingFrag();
getSupportFragmentManager().beginTransaction().add(R.id.receiving_container, frag).commit();
getSupportFragmentManager().executePendingTransactions()
frag.updateText(text);
}
**Edit: This is my MainActivity class that is calling and creating the Fragment:
public class MainActivity extends AppCompatActivity implements SendingFragment.TextClicked {
private static final String TAG = MainActivity.class.getSimpleName();
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String[] myStringArray = {"Hello", "Nice To See You", "Bye"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, myStringArray);
ListView listView = (ListView) findViewById(R.id.mobile_list);
listView.setAdapter(adapter);
sendText("Hello");
}
@Override
public void sendText(String text){
ReceivingFrag frag = new ReceivingFrag();
getSupportFragmentManager().beginTransaction().add(R.id.receiving_container, frag).commit();
getSupportFragmentManager().executePendingTransactions();
frag.updateText(text);
}}
**Edit 2: This is the MainActivity layout file:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/apk/tools"
xmlns:tools2="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="1">
<EditText android:id="@+id/edit_message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:hint="@string/edit_message"
android:layout_weight="1" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="sendMessage"
android:text="@string/button_send"/>
</LinearLayout>
<ListView android:id="@+id/mobile_list"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<FrameLayout
android:id="@+id/receiving_container"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></FrameLayout></LinearLayout>
And this is the layout for the Fragment:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/sender"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/frag_sender"
android:background="@color/gray"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"/></LinearLayout>
Solution: So as mentioned below, the runtime error was fixed by adding
@Override
protected void onResume() {
super.onResume();
sendText("hello");
}
to the MainActivity class. After reading from https://developer.android.com/guide/components/fragments.html#Lifecycle I think the statement
"Once the activity reaches the resumed state, you can freely add and remove fragments to the activity. Thus, only while the activity is in the resumed state can the lifecycle of a fragment change independently."
best explains the situation and why the error initially occurred.
