New to Android.i try to load fragment which insert value in SQLite database in View_Pager tab_Layout which is in Main_Activity.And tried to display data in 2nd fragment in view_pager 2nd tab.but it crashes when run the App..unable to load the fragment in view_pager . here is my code i don't know what is the problem in this code.why it is not loading.
public class MyAdapter extends FragmentPagerAdapter{
String[] name={"Insert","Show"};
@Override
public CharSequence getPageTitle(int position) {
return name[position];
}
public MyAdapter(FragmentManager fm) {
super(fm);
}
@Override
public Fragment getItem(int position) {
switch (position)
{
case 0:InsertFragment im=new InsertFragment();
return im;
case 1:ShowFragment sm=new ShowFragment();
return sm;
}
return null;
}
@Override
public int getCount() {
return 2;
}
}
MainActivity
public class MainActivity extends AppCompatActivity {
TabLayout tabLayout;
ViewPager viewPager;
MyAdapter myAdapter;
MyDatabase m;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
tabLayout=(TabLayout) findViewById(R.id.tabLayout1);
viewPager=(ViewPager) findViewById(R.id.viewPager);
myAdapter=new MyAdapter(getSupportFragmentManager());
//viewPager.setCurrentItem(0);
viewPager.setAdapter(myAdapter);
tabLayout.setupWithViewPager(viewPager);
m=new MyDatabase(this);
m.open();
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
.setAction("Action", null).show();
}
});
}
protected void onDestroy() {
super.onDestroy();
m.close();
}
@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);
}
}
InsertFragment
public class InsertFragment extends Fragment {
EditText name,sub,email;
Button fill1;
public InsertFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(final LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v= inflater.inflate(R.layout.fragment_insert, container, false);
name=(EditText)v.findViewById(R.id.name);
sub=(EditText)v.findViewById(R.id.sub);
email=(EditText)v.findViewById(R.id.email);
fill1=(Button)v.findViewById(R.id.fill);
fill1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(name.getText().toString().equals("") || sub.getText().toString().equals("")||
email.getText().toString().equals(""))
{
Toast.makeText(getActivity(), "please Insert data", Toast.LENGTH_SHORT).show();
}
else {
String Name = name.getText().toString().trim();
String Subject = sub.getText().toString().trim();
String Email = email.getText().toString().trim();
MainActivity main = new MainActivity();
main.m.insertStudent(Name, Subject, Email);
name.setText("");
sub.setText("");
email.setText("");
name.requestFocus();
}
}
});
return v;
}
}
showfragment
public class ShowFragment extends Fragment {
RecyclerView rv;
LinearLayoutManager manager;
Cursor c;
MynewAdapter ma;
public class MynewAdapter extends RecyclerView.Adapter<MynewAdapter.ViewHolder>
{
@Override
public MynewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v=getActivity().getLayoutInflater().inflate(R.layout.row,parent,false);
ViewHolder vh=new ViewHolder(v);
return vh;
}
@Override
public void onBindViewHolder(MynewAdapter.ViewHolder holder, int position) {
if(c!=null) {
c.moveToPosition(position);
int eno = c.getInt(0);
String name1 = c.getString(1);
String sub1=c.getString(2);
String email1=c.getString(3);
holder.tv1.setText("" + eno);
holder.tv2.setText(name1);
holder.tv3.setText(sub1);
holder.tv4.setText(email1);
}
}
@Override
public int getItemCount() {
if(c!=null)
{
return c.getCount();
}
else {
return 0;
}
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView tv1,tv2,tv3,tv4;
public CardView cv;
public ViewHolder(View itemView) {
super(itemView);
tv1=(TextView) itemView.findViewById(R.id.id);
tv2=(TextView) itemView.findViewById(R.id.name);
tv3=(TextView) itemView.findViewById(R.id.sub);
tv4=(TextView) itemView.findViewById(R.id.email);
cv=(CardView) itemView.findViewById(R.id.cv);
}
}
}
public ShowFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
View v= inflater.inflate(R.layout.fragment_show, container, false);
MainActivity mainActivity=(MainActivity) getActivity();
//mainActivity.m.insertEmp(ename,esal,edesig);
c=mainActivity.m.queryStudent();
ma.notifyDataSetChanged();
rv=(RecyclerView) v.findViewById(R.id.rv);
manager = new LinearLayoutManager(getActivity(),LinearLayoutManager.VERTICAL,false);
ma=new MynewAdapter();
rv.setAdapter(ma);
rv.setLayoutManager(manager);
return v;
}
}
Logcat
E/AndroidRuntime: FATAL EXCEPTION: main Process: com.sujalvivek.com.viewpagerdatabasrecyclerassignment, PID: 4931
java.lang.NullPointerException: Attempt to invoke virtual method 'void com.sujalvivek.com.viewpagerdatabasrecyclerassignment.ShowFragment$MynewAdapter.notifyDataSetChanged()' on a null object reference
