Bagaimana untuk menanyakan pangkalan data aktiviti lain dalam satu aktiviti dalam Android?

Question

//Pertama
kes R.id.selectId:

        mmanager=(NotificationManager)this.getSystemService(NOTIFICATION_SERVICE);
        Intent intent=new Intent(this, AllSchool.class);
        PendingIntent pending=PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_CANCEL_CURRENT);
        Notification notification=new Notification.Builder(this)
                .setAutoCancel(true)
                .setTicker("下拉查看")
                .setSmallIcon(R.drawable.ic_launcher)
                .setContentTitle("学校")
                .setContentText("详细信息")
                .setContentIntent(pending)
                .build();
        mmanager.notify(1,notification);
        break;

//Kedua
dilindungi void onCreate(Bundle savedInstanceState) {

    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.manager);
                    
    listViewId=(ListView)findViewById(R.id.listViewId);
    adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,contactList);
    listViewId.setAdapter(adapter);
    readManager();
    
}

public void readManager()
{
    SQLiteDatabase db2=msh.getWritableDatabase();
    Cursor cursor=db2.query("school", null, null, null, null, null, null);
    
    if(cursor.moveToFirst())
    {
        int id=cursor.getInt(cursor.getColumnIndex("id"));
        int phone=cursor.getInt(cursor.getColumnIndex("phone"));
        String name=cursor.getString(cursor.getColumnIndex("name"));
        String address=cursor.getString(cursor.getColumnIndex("address"));
        //Log.d("MainActivity","id is"+id);
        //Log.d("MainActivity","phone is"+phone);
        //Log.d("MainActivity","name is"+name);
        //Log.d("MainActivity","address is"+address);
        
        contactList.add(id+"\n"+phone+"\n"+name+"\n"+address);
        
        
    }

Mesej ralat Pengecualian penuding nol

Answer 1

Mula-mula pastikan anda mempunyai jadual 'sekolah' dalam pangkalan data anda, kemudian pastikan jadual ini mempunyai medan 'id''nama''alamat', dan kemudian pastikan terdapat data dalam jadual selepas mendapat kursor dalam kod Jika ia batal, log ia untuk melihat jika ia adalah batal.