How do I get the cursor value of a ListView's item onItemClick?

Question

I've created a database with tables (categories) with columns (_id, title etc). I want to read these categories' data from my database and list them in a ListView.

Here is my code:

   public class MainActivity extends listActivity{

    private ArrayAdapter arrayAdapter;
    ArrayList results = new ArrayList();
    ListView catlist;
    Cursor cur;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        catlist = getListView();

        int parentid = getIntent().getIntExtra("catid", 0);
        openAndQueryDatabase(parentid);

        displayCatListView();

    }

    private void displayCatListView() {

        setListAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, results));


        catlist.setOnItemClickListener(new OnItemClickListener() {

               @Override
               public void onItemClick(AdapterView<?> parent, View v,
                 final int position, long id) {


                Toast.makeText(MainActivity.this,
                  "List View Clicked:" + position, Toast.LENGTH_LONG)
                  .show();
               }
              });     

    }

    private void openAndQueryDatabase(int parentid) {
        DataBaseHelper db = new DataBaseHelper(this);

        SQLiteDatabase dbr = db.getReadableDatabase();
        cur = dbr.rawQuery(
                "SELECT _id, title, has_sub FROM categories where parent_id=?",
                new String[] { String.valueOf(parentid) });


        if (cur != null) {
            while (cur.moveToNext()) {

                int cat_id = cur.getInt(cur.getColumnIndex("_id"));
                String cattitle = cur.getString(cur.getColumnIndex("title"));
                int has_sub = cur.getInt(cur.getColumnIndex("has_sub"));
                results.add(cat_id + cattitle + has_sub);
            }
            cur.close();
        }

        db.close();

    }
}

I can get the item's position onItemClick, but I want to get their row's _id onItemClick. How do I do this?
I'm new to this. Are there any mistakes in my code?

Thanks a lot.

score 12 · Answer 1 · answered Jul 13 '13 at 19:12

12

Use CursorAdapter(http://developer.android.com/reference/android/widget/CursorAdapter.html) instead, when you are using ArrayAdapter it's exceed memory allocation, and also you wouldn't get notifications if db changed.

Moreover in case of using CursorAdapter you will have

public void onItemClick(AdapterView<?> parent, View v, final int position, long id)

the "id" param will concur with table's _id field

to get the whole row just do

adapter.getItem(int position)

answered Jul 13 '13 at 19:12

Andrew Matiuk

924
1
7
21

This is a much better answer – Gonzo Aug 07 '13 at 04:30
never new id works this way. +1 for this useful info. – Vikash Kumar Verma Jan 26 '17 at 22:08

score 1 · Accepted Answer · answered Jul 13 '13 at 18:14

Instead of

int cat_id = cur.getInt(cur.getColumnIndex("_id"));
String cattitle = cur.getString(cur.getColumnIndex("title"));
int has_sub = cur.getInt(cur.getColumnIndex("has_sub"));
results.add(cat_id + cattitle + has_sub);

create a Category class to contain these values, and use a parameterized ArrayList. Something like

class Category {
    public int cat_id;
    public String cattitle;
    public int has_sub;

    public Category(int cat_id, ...) {
        // constructor logic here
    }
}

and

results.add(new Category(cat_id, cattitle, has_sub));

With this, you can set the onItemClickListener as such:

        catlist.setOnItemClickListener(new OnItemClickListener() {

           @Override
           public void onItemClick(AdapterView<?> parent, View v,
             final int position, long id) {
                 Category clickedCategory = results.get(position);
                 int id = clickedCategory.cat_id;

                 // do something with id
           }
          });

Your ArrayList is the data source of your ArrayAdapter, and position corresponds to the index of the clicked Category in it.

thank you for your answer. could you explain this more this part please: `class Category { public int cat_id; public String cattitle; public int has_sub; public Category(int cat_id, ...) { // constructor logic here } }` or link a complete example? — , Jul 13 '13 at 21:31
@ErikR Could you please point to a full tutorial on using object instead of arraylist? — numediaweb, Oct 05 '13 at 12:59
@numediaweb My code above uses the original ArrayList in Ji.Mack's code to hold instances of the Category class. So we're using objects with an ArrayList, not instead of. — ErikR, Oct 06 '13 at 08:13

How do I get the cursor value of a ListView's item onItemClick?

2 Answers2

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