android retrieve one or few values from arraylist from database

Question

I have made a database and arraylist android passing variables from inside database class , now I am trying to get one or some values from the array list using List<EntryEffectiveRate> allEffectiveRate = db.getAllEffectiveRates(); as for get the all the data lists from the database, however i only able to get all of them using loop :

 // getting all ER
                Log.d("Get ER", "GEtting All ER");

                List<EntryEffectiveRate> allEffectiveRate = db.getAllEffectiveRates();
                for (EntryEffectiveRate ER : allEffectiveRate) {
                    Log.d("ER_ids", String.valueOf(ER.getERId()));
                    Log.d("ER_rates", ER.getERKondisi());
                    Log.d("ER_tenors", String.valueOf(ER.getERTenor()));
                    Log.d("ER_rates", String.valueOf(ER.getERrate()));
                }

how to get just one or few values from the array list?

thanks in advance.

The solution is on the above link, check on the answer.

score 4 · Answer 1 · answered Apr 09 '15 at 06:12

4

i am posting a sample method that i just write in my project, definately it will be according to your requirement.

public ArrayList<SomeModelClass> GetCatagoriesName() {
    close();
    database = this.dbOpenHelper.getReadableDatabase();
    ArrayList<SomeModelClass> catagory_List = new ArrayList<SomeModelClass>();
    String selectQuery = " SELECT " + KEY_CATAGORIES + " FROM "
            + TABLE_CATAGORIES;
    Cursor cursor = database.rawQuery(selectQuery, null);
    if (cursor != null) {
        if (cursor.moveToFirst()) {
            do {
                catagory_List.add(cursor.getString(0));
            } while (cursor.moveToNext());
        }
    }
    return catagory_List;
}

on the other side, just get it from arraylist with position 0, no need to iterate over for loop.

answered Apr 09 '15 at 06:12

Pankaj Arora

10,224
2
37
59

This is good code, but he already had this functionality in place. You can see it in the link to his other question. – Daniel Nugent Apr 09 '15 at 06:39
@DanielNugent i always give hints, never did spoon feeding bro, yes i checked, that's y i post a worked around. – Pankaj Arora Apr 09 '15 at 06:49
1

I did just notice one thing in your code though, be sure to close your cursor! Otherwise you'll have a memory leak. – Daniel Nugent Apr 09 '15 at 07:02
1

Many Thanks, even i saw the same error on logcat, but due to workload i ignored that. +1 – Pankaj Arora Apr 09 '15 at 07:05

score 3 · Accepted Answer · edited Apr 09 '15 at 06:44

Just create a new function that takes a parameter that you can pass to the where clause of your query.

Doing this, you won't have to do any filtering on the ArrayList that's returned from your DatabaseMaster class.

You can create a different function to filter on each database entry you need.

For example, to filter on a certain KEY_ER_USEDORNEW value, the new function would be something like this:

public List<EntryEffectiveRate> getSomeERates(String USEDORNEW) {
        List<EntryEffectiveRate> EffectiveRates = new ArrayList<EntryEffectiveRate>();
        String selectQuery = "SELECT  * FROM " + TABLE_EFFECTIVE_RATE + " where " + KEY_ER_USEDORNEW + " = ?";

        Log.e(LOG, selectQuery);

        SQLiteDatabase db = this.getReadableDatabase();
        Cursor c = db.rawQuery(selectQuery, new String[] {USEDORNEW});

        // looping through all rows and adding to list
        if (c.moveToFirst()) {
            do {
                EntryEffectiveRate ergt = new EntryEffectiveRate();

                ergt.setERKondisi(c.getString(c
                        .getColumnIndex(KEY_ER_USEDORNEW)));              
                // add
                EffectiveRates.add(ergt);
            } while (c.moveToNext());
        }
        // db.close();
        c.close();
        return EffectiveRates;
    }

To call this from your Activity, you would pass the filter value as a parameter:

           String USEDORNEW = "Baru";
           List<EntryEffectiveRate> someEffectiveRates = db.getSomeERates(USEDORNEW);
            for (EntryEffectiveRate ER : someEffectiveRates) {           
                Log.d("ER_rates", ER.getERKondisi());
            }

would you please also tell me how to call this function in the activity class? (an example) — Jedi Fighter, Apr 09 '15 at 06:15
@JediFighter I just realized that initially I used the wrong function as a reference. I just fixed it. — Daniel Nugent, Apr 09 '15 at 06:29

score 1 · Answer 3 · answered Apr 09 '15 at 05:50

1

You can use ...

List.get(index);

method for getting the specific or one value from the list without looping it. But if you want more then one value then you have to loop it.

answered Apr 09 '15 at 05:50

Khubab Hamza

184
12

score 1 · Answer 4 · answered Apr 09 '15 at 05:59

Use the Following code to get just one value from arraylist

   List<EntryEffectiveRate> allEffectiveRate =  db.getAllEffectiveRates();
   EntryEffectiveRate ER =allEffectiveRate.get(position);
   Log.d("ER_ids", String.valueOf(ER.getERId()));
   Log.d("ER_rates", ER.getERKondisi());
   Log.d("ER_tenors", String.valueOf(ER.getERTenor()));
   Log.d("ER_rates", String.valueOf(ER.getERrate()));

Darshan Kachhadiya · Answer 5 · 2015-04-09T08:52:34.130

//use for loop as like below

for(int i=0;i<allEffectiveRate.size();i++)
  { 
     EntryEffectiveRate ER =allEffectiveRate.get(i);  
     Log.d("ER_ids"String.valueOf(ER.getERId()) ;
     Log.d("ER_rates", ER.getERKondisi());
     Log.d("ER_tenors", String.valueOf(ER.getERTenor()));
      Log.d("ER_rates", String.valueOf(ER.getERrate()));

}

//if after that u can't get propar data at then problem with ur method //db.getAllEffectiveRates();

android retrieve one or few values from arraylist from database

5 Answers5