I have reviewed multiple solutions to my question, but each attempt results in my android application crashing due to the data being sent returning null. I am attempting to send a ArrayList of Strings to a fragment, but when I launch my application I receive the following error.
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.assignment2, PID: 17719
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.assignment2/com.example.assignment2.MainActivity}: android.view.InflateException: Binary XML file line #9 in com.example.assignment2:layout/activity_main: Binary XML file line #9 in com.example.assignment2:layout/activity_main: Error inflating class fragment
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3449)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
Caused by: android.view.InflateException: Binary XML file line #9 in com.example.assignment2:layout/activity_main: Binary XML file line #9 in com.example.assignment2:layout/activity_main: Error inflating class fragment
Caused by: android.view.InflateException: Binary XML file line #9 in com.example.assignment2:layout/activity_main: Error inflating class fragment
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.ArrayList android.os.Bundle.getStringArrayList(java.lang.String)' on a null object reference
at com.example.assignment2.TickerListFragment.onCreateView(TickerListFragment.java:21)
at androidx.fragment.app.Fragment.performCreateView(Fragment.java:2963)
at androidx.fragment.app.FragmentStateManager.ensureInflatedView(FragmentStateManager.java:386)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:281)
at androidx.fragment.app.FragmentLayoutInflaterFactory.onCreateView(FragmentLayoutInflaterFactory.java:140)
at androidx.fragment.app.FragmentController.onCreateView(FragmentController.java:135)
at androidx.fragment.app.FragmentActivity.dispatchFragmentsOnCreateView(FragmentActivity.java:319)
at androidx.fragment.app.FragmentActivity.onCreateView(FragmentActivity.java:298)
at android.view.LayoutInflater.tryCreateView(LayoutInflater.java:1067)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:995)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:959)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1121)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1082)
at android.view.LayoutInflater.inflate(LayoutInflater.java:680)
at android.view.LayoutInflater.inflate(LayoutInflater.java:532)
at android.view.LayoutInflater.inflate(LayoutInflater.java:479)
at androidx.appcompat.app.AppCompatDelegateImpl.setContentView(AppCompatDelegateImpl.java:706)
at androidx.appcompat.app.AppCompatActivity.setContentView(AppCompatActivity.java:195)
at com.example.assignment2.MainActivity.onCreate(MainActivity.java:18)
at android.app.Activity.performCreate(Activity.java:8000)
at android.app.Activity.performCreate(Activity.java:7984)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3422)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3601)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
E/AndroidRuntime: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2066)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:223)
at android.app.ActivityThread.main(ActivityThread.java:7656)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
W/System: A resource failed to call close.
The following is my MainActivity class
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import android.os.Bundle;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
ArrayList<String> tickers;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
getSupportActionBar().hide();
tickers = new ArrayList<String>();
tickers.add("BAC");
tickers.add("BTC");
tickers.add("APPL");
FragmentManager fragmentManager = getSupportFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
Bundle bundle = new Bundle();
bundle.putStringArrayList("def", tickers);
TickerListFragment list = new TickerListFragment();
list.setArguments(bundle);
fragmentTransaction.replace(R.id.list_fragment, list).commit();
}
}
The following is the XML for the main activity class.
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<fragment
android:id="@ id/list_fragment"
android:name="com.example.assignment2.TickerListFragment"
android:layout_width="wrap_content"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
The following is the fragment class
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.Toast;
import androidx.fragment.app.Fragment;
import java.util.ArrayList;
public class TickerListFragment extends Fragment {
ArrayList<String> def_tickers;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle state) {
View view = inflater.inflate(R.layout.fragment_tickerlist, container, false);
def_tickers = this.getArguments().getStringArrayList("def");
return view;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
LinearLayout layout = (LinearLayout) view.findViewById(R.id.list_layout);
}
}
And the following is the XML for the fragment
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@ id/list_layout"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:orientation="vertical">
</LinearLayout>
</ScrollView>
If someone could point out my oversight as to why the sent data is being retrieved as null that would be much appreciated.
CodePudding user response:
AFAIK when you use <fragment>
in xml it is automatically inflated, when the view is inflated, i.e. setContentView(R.layout.activity_main);
This means the fragment is created before you got the chance to pass in the bundled args.
Back in the day it was standard practice to use a FrameLayout
instead like you've stated in your comment. But now it is best to use FragmentContainerView
as it respects animations among other things.
<FragmentContainerView
android:id="@ id/list_fragment"
android:layout_width="wrap_content"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />