Issue
I'm new to android. Recently I tried communication between 2 fragments via activity. Basically here i'm sending the position of the button pressed from one fragment to another fragment that consist of a textview. But i'm getting the error: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
I tried if the value id even being passed or not. i printed the value on Log and it was successfully printed. I have searched a lot over this error and tried alternatives; using method,rootView instead of getView() but nothing seems to work out. I might be making a silly mistake but i really to get through with this.
MainActivity.java
package com.example.benchtobasecamp.doublelistfragment;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.support.v4.app.FragmentTransaction;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends FragmentActivity implements BlankFragment.OnItemClickListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void method1(int position)
{
ResultFragment rf=new ResultFragment();
Bundle bundle = new Bundle();
bundle.putString("value", String.valueOf(position));
rf.setArguments(bundle);
FragmentTransaction fragmentManager=getSupportFragmentManager().beginTransaction();
fragmentManager.replace(R.id.frame_container,rf);
fragmentManager.addToBackStack(null);
fragmentManager.commit();
}
}
BlankFragment.jav
package com.example.benchtobasecamp.doublelistfragment;
import android.content.Context;
import android.support.v4.app.ListFragment;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
public class BlankFragment extends ListFragment {
OnItemClickListener listener;
public interface OnItemClickListener
{
public void method1(int position);
}
@Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
ArrayAdapter<CharSequence> adapter=ArrayAdapter.createFromResource(getActivity(), R.array.Buttons, android.R.layout.simple_list_item_1);
setListAdapter(adapter);
getListView().setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
switch (position)
{
case 0:listener.method1(0);
break;
case 1:listener.method1(1);
break;
case 2:listener.method1(2);
break;
}
}
});
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view= inflater.inflate(R.layout.fragment_blank, container, false);
return view;
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
try{
listener = (OnItemClickListener) context;
}
catch(ClassCastException e) {
throw new ClassCastException(context.toString() + " must implement MyListFragment.OnItemSelectedListener");
}
}
}
ResultFragment
package com.example.benchtobasecamp.doublelistfragment;
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.TextView;
public class ResultFragment extends Fragment {
TextView textView;
public ResultFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Bundle bundle = this.getArguments();
String Value = bundle.getString("value");
//Log.d("You pressed Button",String.valueOf(position+1));
textView= (TextView) getActivity().findViewById(R.id.textView);
textView.setText(Value);
}
}
The logcat is showing this error:
01-20 11:33:24.084 1923-1923/com.example.benchtobasecamp.doublelistfragment E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.benchtobasecamp.doublelistfragment, PID: 1923
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.example.benchtobasecamp.doublelistfragment.ResultFragment.onCreate(ResultFragment.java:34)
at android.support.v4.app.Fragment.performCreate(Fragment.java:1942)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1040)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1259)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1624)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Solution
Here:
textView= (TextView) getActivity().findViewById(R.id.textView);
getActivity()
return container Activity
Context, if we use getActivity()
to call findViewById
method means accessing Views from Activity
layout instead of Fragment
.
To access View from Fragment
layout use onCreateView
in same way as ding in BlankFragment
Fragment.
override onCreateView
method in BlankFragment
Fragment:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View view= inflater.inflate(
R.layout.<pass layout id which contains TextView with textView id>,
container, false);
TextView textView= (TextView) view.findViewById(R.id.textView);
Bundle bundle = this.getArguments();
String Value = bundle.getString("value");
textView.setText(Value);
return view;
}
Answered By - ρяσѕρєя K
0 comments:
Post a Comment
Note: Only a member of this blog may post a comment.