Error:(56, 28) error: cannot find symbol method clear()

[John Joe]

Good day guys. I have a listView, and AllAdapter adapter where the AllAdapter is extending to BaseAdapter

Why I get error on line adapter.clear()?

Error

Error:(56, 28) error: cannot find symbol method clear()

Code

 

  public void retrieveList(String name)
        {
            database= mdb.getReadableDatabase();
            Cursor cursor = database.rawQuery("SELECT Title FROM " + MyDatabaseHelper.TABLE__TASK + " WHERE NAME = ? " ,new String[]{name},null);
            if (cursor!=null && cursor.getCount()>0) {
                while (cursor.moveToNext()) {
                    String idx = cursor.getString(cursor.getColumnIndex("Title"));
                    if(adapter!=null) {
                        adapter.clear();
                        adapter.add(idx);
                        listview.setAdapter(adapter);
                    }
                }
            }
            else
            {
                Toast.makeText(getApplication(),"null", Toast.LENGTH_SHORT).show();
            }
        }

[Rob Spoor]

BaseAdapter doesn't have a clear() method. That means that you will need to declare adapter as AllAdapter and not as BaseAdapter. Can you show us how you declared adapter?

[John Joe]

Rob Spoor wrote:BaseAdapter doesn't have a clear() method. That means that you will need to declare adapter as AllAdapter and not as BaseAdapter. Can you show us how you declared adapter?

This is how I declare adapter

AllAdapter adapter;
ArrayList<SearchList> search = new ArrayList<SearchList>();
ListView listview;

And code after setContentView

adapter=new AllAdapter(getApplication(),search,listview);

And finally AllAdapter Class

public class AllAdapter extends BaseAdapter {

    Context context;
    private static ArrayList<SearchList> search;
    private LayoutInflater mInflater;
    ListView listview;

    public AllAdapter(Context context, ArrayList<SearchList> searchList, ListView listview) {
        search=searchList;
        this.listview=listview;
        mInflater = LayoutInflater.from(context);
    }
  
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.item_to_do, null);
            holder= new ViewHolder();
            holder.text = (TextView) convertView.findViewById(R.id.task_title);
            convertView.setTag(holder);
        }
        holder = (ViewHolder) convertView.getTag();
        holder.text.setText(search.get(position).getTitle());
        return convertView;
    }

    static class ViewHolder {
        TextView text;

    }
}

[Norm Radder]

cannot find symbol method clear()

Where do you think the method clear() is defined? What class in what package?

[John Joe]

Norm Radder wrote:

cannot find symbol method clear()

Where do you think the method clear() is defined? What class in what package?

I post part of my code here.

public class ReminderPage extends AppCompatActivity {

    private MyDatabaseHelper mdb;
    private SQLiteDatabase database;
    AllAdapter adapter;
    ArrayList<SearchList> search = new ArrayList<SearchList>();
    ListView listview;
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.reminder_page);
        mdb=new MyDatabaseHelper(this);
        database= mdb.getReadableDatabase();
        listview = (ListView) findViewById(R.id.list_todo);
        adapter=new AllAdapter(getApplication(),search,listview);
        retrieveList(name);
    }

    public void retrieveList(String name)
    {
        database= mdb.getReadableDatabase();
        Cursor cursor = database.rawQuery("SELECT Title FROM " + MyDatabaseHelper.TABLE__TASK + " WHERE NAME = ? " ,new String[]{name},null);
        if (cursor!=null && cursor.getCount()>0) {
            while (cursor.moveToNext()) {
                String idx = cursor.getString(cursor.getColumnIndex("Title"));
                if(adapter!=null) {
                    adapter.clear(); // clear cannot be resolved
                    adapter.add(idx);
                    listview.setAdapter(adapter);
                    adapter.getCount();
                    if (search.size() == 0) {
                        imageView.setVisibility(View.VISIBLE);
                        textView.setVisibility(View.VISIBLE);
                        button.setVisibility(View.VISIBLE);
                    } else {
                        imageView.setVisibility(View.GONE);
                        textView.setVisibility(View.GONE);
                        button.setVisibility(View.GONE);
                    }
                }
            }
        }
        else
        {
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.add_task, menu);
        return super.onCreateOptionsMenu(menu);
    }

  
}

[Norm Radder]

That doesn't answer my question:
Where do you think the clear() method is defined?  What class is it in?
If the compiler can not find a definition for a method it will flag that statement as an error.

[John Joe]

Norm Radder wrote:That doesn't answer my question:
Where do you think the clear() method is defined?  What class is it in?
If the compiler can not find a definition for a method it will flag that statement as an error.

Do you mean that I need to create a clear method in AllAdapter class ? I would like to clear all the listview item first before they added into listview.

[Norm Radder]

Do you mean that I need to create a clear method in AllAdapter class ?

You can not call a method that does not exist.  If you want the AllAdapter class to have a clear method, you will have to write it.

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