无限循环。 从数据库中读取数据并将其与if语句进行比较

Question

My English is a little rusty, but I will try to explain what I want to do.

I have a database and 5 rows in it. I am trying to do something like this:

1. Read n rows from database.
2. Assign data from database to variables
3. Check if variables belongs to the condition
   if(((szerokosc<=a)&&(szerokosc>=b)) && ((dlugosc>=c)&&(dlugosc<=d)))
4. if yes, display (opis)
5. if not, display(brak danych)
6. if end of rows go to first
7. if there exists next row, go to it,

I want to do this over and over again;

public void onLocationChanged(Location location)
{
    showLocation(location);
    showAdditionalInfo(location);
    if(savedLocation == null)
    savedLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
    DataBaseHelper zb = new DataBaseHelper(getApplicationContext());
    double szerokosc = location.getLatitude();
    double dlugosc = location.getLongitude();
    Cursor k = zb.dajCos();
    String lokalizacja = "Jestes na: ";
    while(k.moveToNext())
    {
        nazwa = k.getString(0);
        szmax= k.getDouble(1);
        szmin= k.getDouble(2);
        dlmin= k.getDouble(3);
        dlmax= k.getDouble(4);
        opis = k.getString(5);
        a=szmax;
        b=szmin;
        c=dlmin;
        d=dlmax; 
        if(k.moveToNext()==false){k.moveToFirst();}
    }
    if(((szerokosc<=a)&&(szerokosc>=b)) && ((dlugosc>=c)&&(dlugosc<=d)))
    {
        lokalizacja =nazwa+opis;
    }
    else
    {
        lokalizacja ="brak danych";
    }
    tvLokalizacja.setText(lokalizacja);
}

This is public Cursor dajCos()

public Cursor dajCos() 
{
     String[] kolumny={"nazwa","szmax","szmin","dlmin","dlmax","opis"};
     SQLiteDatabase db = getReadableDatabase();
     Cursor kursor = db.query("obiekty", kolumny, null, null, null, null, null);
     return kursor;
}

I dont know how to explain this better. I will try to describe this in that way.

In database I have 5 records each of them include coordinates. For example: My position corresponds to coordinates from second row , I want to display you are in "zone1", I move ten meters away and my position don't match to coordinates in any row so I want to display "no data", I move fifteen meters away then fourth row coordinates match to my position and display you are in "zone2".

I hope you will understand what I mean and help me. Thank you.

Answer 1

I have this loop:

 k.moveToFirst(); //iterate over rows for (int i = 0; i < k.getCount(); i++) { nazwa = k.getString(0); szmax= k.getDouble(1); szmin= k.getDouble(2); dlmin= k.getDouble(3); dlmax= k.getDouble(4); opis = k.getString(5); a=szmax; b=szmin; c=dlmin; d=dlmax; wypisz +=i+nazwa+"-"+a+"-"+opis+"\\n"; tvBaza.setText(wypisz); k.moveToNext(); } 

the loop execute 5 times because I have 5 rows in database. I want to change it to execute over and over again.

Answer 2

Could You give me a clue. I don't know how to explain this. My database have 5 rows. They looks like that:

---

1 Zone_A(nazwa), 50.03233693(dlmax), 50.0281259(dlmin), 22.00383871(szmin), 22.0094177(szmax), You are in zone_A(opis).

---

As You see I have coordinates and names in them. My goal is to achieve somethin like that.

When my location change I get in to database check each row, if coordinates from one of them mach to the statement

    if(((szerokosc<=a)&&(szerokosc>=b)) && ((dlugosc>=c)&& (dlugosc<=d)))`

where

    a=szmax;b=szmin;c=dlmin;d=dlmax; 

and

    double szerokosc = location.getLatitude();
    double dlugosc = location.getLongitude();

if they match display (nazwa+opis) if not dispaly(brak danych). When I am moving then data in

    double szerokosc = location.getLatitude();
    double dlugosc = location.getLongitude();

are changing too.

So I have to get in to database againg to check if one of row fits to new coordinates obtained from GPS which are saved in

    double szerokosc = location.getLatitude();
    double dlugosc = location.getLongitude();