如何从android sqlite数据库中获取多个项目并将其存储在数组中？

Question

I m using static database to fetch data. I m fetching longitude and latitude of static location from database, storing it in string and using. What if i want to extract all longitude and latitude and store it in an array...i mean array of size [137][15] storing latitude and longitude in a single 2d array.....or 2 separate 1 d array. One for latitude ..another for latitude...

DataBaseHelper2 mDbHelper = new DataBaseHelper2(this);
try {
    mDbHelper.createDataBase();
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}      
try {
    mDbHelper.openDataBase();
} catch (SQLException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}   
    Spinner s1=(Spinner) findViewById(R.id.spinner1);
    int index1=s1.getSelectedItemPosition();
    String Text1 = s1.getSelectedItem().toString();
    String Text3="";
    String Text4="";

    if(index1==0)
    {
        Toast.makeText(getApplicationContext(),"Please Enter station", Toast.LENGTH_SHORT).show();
    }
    else{
    Cursor c=mDbHelper.fetchQuery(Text1);

    int latitude =  c.getColumnIndex("lat");
    int longitude = c.getColumnIndex("lng");

    for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
        Text3=Text3 + c.getString(latitude)+"\n";
        Text4=Text4 + c.getString(longitude)+"\n";
    }

    Double p,p1;
    p=Double.valueOf(Text3).doubleValue();
    p1=Double.valueOf(Text4).doubleValue();

fetchquery is a method to extract longitude and latitude where name of station matches with text of spinner1.

Answer 1

Use List<BasicNameValuePair> they will be stored in key-value manner. As you iterate store them add them in the list like:

List<BasicNameValuePair> latLongList = new ArrayList<BasicNameValuePair>();
 for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
        latLongList.add(new BasicNameValuePair(c.getString(latitude), c.getString(longitude)));
    }

Then you can use it where ever you want. In thiscase latitude will be key and longitude will be value.

This is one way of doing this. Also instead BasicNameValuePair you can use android.location.Location and set in same manner.

Answer 2

I think you'll run into more trouble than it's worth using a 2 dimensional array for this. If you wanna persist 2 regular arrays, then perhaps you could check out the following code:

        if(index1==0){
            Toast.makeText(getApplicationContext(),"Please Enter station", Toast.LENGTH_SHORT).show();
        }else{
        Cursor c=mDbHelper.fetchQuery(Text1);
        arrLatitude = new String [c.getCount()];
        arrLongitude = new String [c.getCount()];

        int latitude =  c.getColumnIndex("lat");
        int longitude = c.getColumnIndex("lng");

        i = 0;
        for(c.moveToFirst();!c.isAfterLast();c.moveToNext()){
            Text3=Text3 + c.getString(latitude)+"\n";
            Text4=Text4 + c.getString(longitude)+"\n";
            arrLatitude[i] = Text3;
            arrLongitude[i] = Text4;
        i++;
        }

Personally, I'd rather do it with an object to hold both of these Strings together. That way you'd have peace of mind in case the indexes become mismatched for whatever reason.