Unfortunately, "App" has stopped

i'm a student learning for this android programming. in this program i'm trying to create entry database. When i run the program in go smooth for the main activity, but the second activity gave me the "app stop working" message.

1. 
   

   Main Activity

   
   

   
   public class MainActivity extends Activity {
       private ListView list;
       private TextView txt;
       private List<Notes> notes;
       private ArrayAdapter<String> adapter;
       private ArrayList<String> arrlist;
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
           notes = data();
           arrlist = data_Notes();
   
           setContentView(R.layout.activity_main);
           list = (ListView)findViewById(R.id.note_data);
           txt = (TextView)findViewById(R.id.total_data);
   
           adapter = new ArrayAdapter<String>  (MainActivity.this,android.R.layout.simple_list_item_1,arrlist);
           list.setAdapter(adapter);
   
           if (notes.size()>0){
               txt.setText(notes.size()+" note saved");
           }else {
               txt.setText("Note not yet available");
           }
       }
       public List<Notes> data(){
           return new NotesRepo(MainActivity.this).listall();
       }
       public ArrayList<String> data_Notes(){
           ArrayList<String> dt = new ArrayList<String>();
           for (int i = 0; i < data().size(); i++){
               dt.add(data().get(i).getJudul());
           }
           return dt;
       }
       public void tambah_data(View view){
           startActivity(new Intent(MainActivity.this,AddActivity.class));
       }
   
   
   
       @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);
       ///}
   }
   
   



2. 
   

   Second Activity

   
   

   
   public class AddActivity extends Activity{
       private EditText title;
       private EditText body;
       @Override
       protected void onCreate(Bundle savedInstanceState){
           super.onCreate(savedInstanceState);
           setContentView(R.layout.add_data);
           title = (EditText)findViewById(R.id.title_data);
           body = (EditText)findViewById(R.id.body_data);
       }
       public void save_data (View view){
           Notes notes = new Notes();
           notes.setJudul(title.getText().toString());
           notes.setIsi(body.getText().toString());
           try{
               new NotesRepo(AddActivity.this).create(notes);
               Toast.makeText(AddActivity.this, "data saved",         Toast.LENGTH_LONG).show();
           }catch (SQLException e){
               Toast.makeText(AddActivity.this, "failed to save data",         Toast.LENGTH_LONG).show();
               e.printStackTrace();
           }
           startActivity(new         Intent(AddActivity.this,MainActivity.class).addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP));
           finish();
       }
   }
   
   



3. 
   

   activity_main.xml

   
   

   
   <RelativeLayout xmlns:android="http://ift.tt/nIICcg"
       xmlns:tools="http://ift.tt/LrGmb4"         android:layout_width="match_parent"
       android:layout_height="match_parent"         android:paddingLeft="@dimen/activity_horizontal_margin"
       android:paddingRight="@dimen/activity_horizontal_margin"
       android:paddingTop="@dimen/activity_vertical_margin"
       android:paddingBottom="@dimen/activity_vertical_margin"         tools:context=".MainActivity">
   
       <LinearLayout
           android:layout_width="match_parent"
           android:layout_height="wrap_content" >
           <TextView
               android:id="@+id/total_data"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"
               android:layout_marginBottom="10dp"
               android:layout_weight="0.3"
               android:text="Data Tersimpan"
               android:textAppearance="?android:attr/textAppearanceMedium"
               />
   
           <Button
               android:id="@+id/button1"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"
               android:layout_weight="1"
               android:onClick="tambah_data"
               android:text="+" />
       </LinearLayout>
       <ListView
           android:id="@+id/note_data"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:layout_alignParentLeft="true" >
       </ListView>
   
   </RelativeLayout>
   
   



4. 
   

   Add_data.xml (second activity xml)

   
   

   
   <?xml version="1.0" encoding="utf-8"?>
   <LinearLayout xmlns:android="http://ift.tt/nIICcg"
       android:layout_width="match_parent"
       android:layout_height="match_parent"
       android:orientation="vertical"
       android:paddingBottom="@dimen/activity_vertical_margin"
       android:paddingLeft="@dimen/activity_horizontal_margin"
       android:paddingRight="@dimen/activity_horizontal_margin"
       android:paddingTop="@dimen/activity_vertical_margin" >
   
       <TextView
           android:id="@+id/textView1"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:text="Title"
           android:textAppearance="?android:attr/textAppearanceMedium" />
       <EditText
           android:id="@+id/title_data"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:layout_marginTop="10dp"
           android:ems="10" >
           <requestFocus />
       </EditText>
       <TextView
           android:id="@+id/textView2"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:layout_marginTop="10dp"
           android:text="Body"
           android:textAppearance="?android:attr/textAppearanceMedium" />
       <LinearLayout
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:layout_weight="0.2"
           android:orientation="vertical" >
           <EditText
               android:id="@+id/body_data"
               android:layout_width="match_parent"
               android:layout_height="wrap_content"
               android:layout_marginTop="10dp"
               android:background="#fff"
               android:ems="10"
               android:hint="isi notes"
               android:inputType="textMultiLine" />
       </LinearLayout>
       <Button
           android:id="@+id/button1"
           android:layout_width="match_parent"
           android:layout_height="wrap_content"
           android:text="Button" />
   
   </LinearLayout>