I am trying to use the new RecyclerView widget inside a Fragment but I am getting this error:
Unable to start activity
ComponentInfo{com.example.myapplication/com.example.myapplication.MyActivity}:
java.lang.NullPointerException: Attempt to invoke interface method
'boolean java.util.List.add(java.lang.Object)' on a null object
reference
What am I doing wrong?
This is my Fragment:
import android.app.Fragment;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import java.util.List;
public class RecyclerviewFragment extends Fragment {
private RecyclerView mRecyclerView;
private RecyclerviewAdapter mRecyclerviewAdapter;
private LinearLayoutManager mLinearLayoutManager;
private List<ViewModel> viewModel;
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_recyclerview, container, false);
mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recycler_view);
return rootView;
}
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
mRecyclerviewAdapter = new RecyclerviewAdapter(viewModel);
mLinearLayoutManager = new LinearLayoutManager(getActivity());
mRecyclerView.setAdapter(mRecyclerviewAdapter);
mRecyclerView.setLayoutManager(mLinearLayoutManager);
mRecyclerView.setItemAnimator(new DefaultItemAnimator());
}
}
And my Activity:
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import java.util.List;
public class MyActivity extends Activity {
private List<ViewModel> viewModel;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
RecyclerviewFragment recyclerviewFragment = new RecyclerviewFragment();
getFragmentManager().beginTransaction().add(android.R.id.content, recyclerviewFragment).commit();
viewModel.add(new ViewModel("View"));
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.my, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Thanks!
You didn't initialize private List<ViewModel> viewModel
Related
i'm trying to add sliding tabs in my application following one guide from google, but i'm getting this error when i try to start application:
05-29 02:04:40.353: E/AndroidRuntime(21092): java.lang.NullPointerException: Attempt to invoke virtual method 'int android.os.Bundle.getInt(java.lang.String)' on a null object reference
05-29 02:50:06.212: E/AndroidRuntime(3506): at com.tabs.dusandimitrijevic.Tab1.onCreate(Tab1.java:33)
Here are my one Fragment Tab:
package com.tabs.dusandimitrijevic;
import com.dusandimitrijevic.spisakzakupovinu.R;
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.TextView;
/**
* Created by hp1 on 21-01-2015.
*/
//In this case, the fragment displays simple text based on the page
public class Tab1 extends Fragment {
public static final String ARG_PAGE = "ARG_PAGE";
private int mPage;
public static Tab1 newInstance(int page) {
Bundle args = new Bundle();
args.putInt(ARG_PAGE, page);
Tab1 fragment = new Tab1();
fragment.setArguments(args);
return fragment;
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPage = getArguments().getInt(ARG_PAGE);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.tab_1, container, false);
TextView textView = (TextView) view;
textView.setText("Fragment #" + mPage);
return view;
}
}
And here are my FragmentPagerAdapter:
package com.tabs.dusandimitrijevic;
import android.R;
import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentStatePagerAdapter;
/**
* Created by hp1 on 21-01-2015.
*/
public class SampleFragmentPagerAdapter extends FragmentPagerAdapter {
final int PAGE_COUNT = 3;
private String tabTitles[] = new String[] { "Tab1", "Tab2", "Tab3" };
private Context context;
public SampleFragmentPagerAdapter(FragmentManager fm, Context context) {
super(fm);
this.context = context;
}
#Override
public int getCount() {
return PAGE_COUNT;
}
#Override
public Fragment getItem(int position) {
switch (position) {
case 0:
return new Tab1();
case 1:
return new Tab2();
case 2:
return new Tab3();
}
return null;
}
#Override
public CharSequence getPageTitle(int position) {
// Generate title based on item position
return tabTitles[position];
}
}
And here are my MainActivity:
package com.dusandimitrijevic.spisakzakupovinu;
import java.util.ArrayList;
import com.tabs.dusandimitrijevic.SampleFragmentPagerAdapter;
import com.tabs.dusandimitrijevic.SlidingTabLayout;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
private Toolbar toolbar;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
toolbar = (Toolbar) findViewById(R.id.app_bar);
setSupportActionBar(toolbar);
// Get the ViewPager and set it's PagerAdapter so that it can display items
ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
viewPager.setAdapter(new SampleFragmentPagerAdapter(getSupportFragmentManager(),
MainActivity.this));
// Give the SlidingTabLayout the ViewPager
SlidingTabLayout slidingTabLayout = (SlidingTabLayout) findViewById(R.id.tabs);
// Center the tabs in the layout
slidingTabLayout.setDistributeEvenly(true);
slidingTabLayout.setViewPager(viewPager);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
Toast.makeText(MainActivity.this, "Ovo su podešavanja", Toast.LENGTH_SHORT).show();
return true;
}
if(id == R.id.navigate){
Intent i= new Intent(MainActivity.this, SubActivity.class);
startActivity(i);
}
return super.onOptionsItemSelected(item);
}
}
Can anyone help me with this?
You have coded a static factory function to create your fragments , but you don't use it ?!
Your adapter should create the fragments using it:
#Override
public Fragment getItem(int position) {
return Tab1.newInstance(position);
}
Trying to create a switch in android with default ON state and with OnCheckedChangeListener. But application is force closing. What is wrong? please help. New in android development.
package com.tiumca2013.smarthousecontrol;
import android.app.Activity;
import android.app.Fragment;
import android.bluetooth.BluetoothAdapter;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.Switch;
import android.widget.Toast;
public class MainActivity extends Activity{
private Switch switch1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
switch1 = (Switch) findViewById(R.id.Switch1);
switch1.setChecked(true); // force close
switch1.setOnCheckedChangeListener(new OnCheckedChangeListener() // force close again
{
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked)
{
if(isChecked)
Toast.makeText(getApplicationContext(),"switch 1 ON",Toast.LENGTH_SHORT).show();
else
Toast.makeText(getApplicationContext(),"switch 1 OFF",Toast.LENGTH_SHORT).show();
}
});
if (savedInstanceState == null) {
getFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
I dont know what happen with my sdk and eclipse. I install google services,it is install successfully but now i add activity to my old project but now .java file is extends FragementActivity. i dont know why this is happen. Please give reply please.
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
public class WebViewActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.web_view);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.web_view, 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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
I can't to get the button from fragment, what's wrong?
Recieve a uncaught exception - nullpointerexception;
Button can't be found.
Early all will be find, but after update android sdk, all is changed ((
package com.example.test;
import java.io.IOException;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity implements OnClickListener {
Button play, pause;
MediaPlayer mplayer;
RadioGroup rgroup;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i("MyTAG", "1");
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
mplayer = new MediaPlayer();
rgroup = (RadioGroup) findViewById(R.id.radioGroup1);
play = (Button) findViewById(R.id.play);
pause = (Button) findViewById(R.id.pause);
play.setOnClickListener(this);
pause.setOnClickListener(this);
}
#Override
public void onClick(View v) {
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
p.s. sorry for my english
You are trying to search inside Activity's layout, and your widgets are inside a Fragment's layout.
Put your logic inside your PlaceHolderFragment class:
public static class PlaceholderFragment extends Fragment implements OnClickListener {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
mplayer = new MediaPlayer();
rgroup = (RadioGroup) rootView.findViewById(R.id.radioGroup1);
play = (Button) rootView.findViewById(R.id.play);
pause = (Button) rootView.findViewById(R.id.pause);
play.setOnClickListener(this);
pause.setOnClickListener(this);
return rootView;
}
#Override
public void onClick(View v) {
}
}
P.S. Салам алейкум =)
I am new to android development.I am trying to create an activity method on clicking a button.
Below is my MainActivity.java file code.
I am getting errors
1."cannot resolve method'setVisibility (int)'" and
2."cannot resolve symbol 'TextView'"
please guide.
MainActivity.java
package com.AndroidLove;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
public void onLoveButtonClicked(View view) {
TextView textView =(TextView) findViewById(R.id.textView);
textView.setVisibility(View.VISIBLE);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
//Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.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.
switch (item.getItemId()) {
case R.id.action_settings:
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
Import this package as well
import android.widget.TextView;