@Override
public int getIDmax() {
    int MAX =0;
    SQLiteDatabase db = this.getReadableDatabase();
    try{
        String QUERY = "SELECT MAX(KEY_MESSAGE_ID) AS KEY_MESSAGE_ID FROM "+TABLE_NAME ;
        Cursor cursor = db.rawQuery(QUERY,null);
        MAX =cursor.getColumnIndex(KEY_MESSAGE_ID);
        db.close();
        return MAX;

    }catch (Exception e){
        Log.e("error",e+"");
    }
   return 0;
}

int b = handler.getIDmax();
            Toast.makeText(getApplicationContext(),""+b,Toast.LENGTH_LONG).show();