Rows being repeated in ListView

Question

I know this question has appeared a number of times but for some reason I can't seem to get it to work. The fact that getView is called multiple times in certain cases.

However, in the example given here: http://android.amberfog.com/?p=296 it says that the first call for each row in the data should get a null value in currentView. This is not happening.

What is happening for me is that the calls when position is 0 has currentView set to null whereas the calls where position is 1 has currentView set to an existing object.

In total 16 calls are made to "getView" but I get the rows duplicated once (i.e two of each row). Row 0 Row 1 Row 0 Row 1

I probably just didn't understand something from that post.

Layout:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"   
    android:layout_height="fill_parent"
    >
    <TextView android:id="@+id/title_paired_devices" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/title_paired_devices" 
        android:visibility="gone"
        android:background="#666"
        android:textColor="#fff"
        android:paddingLeft="5dp"
    />
    <ListView android:id="@+id/paired_devices"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:stackFromBottom="true"
        android:layout_weight="1"
    />
    <TextView android:id="@+id/title_new_devices"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/title_other_devices"
        android:visibility="gone"
        android:background="#666"
        android:textColor="#fff"
        android:paddingLeft="5dp"
    />
    <ListView android:id="@+id/new_devices"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:stackFromBottom="true"
        android:layout_weight="2"
    />
    <Button android:id="@+id/button_scan" 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/button_scan"
    />
</LinearLayout>

Listview row:

    <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.

android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/list_selector"
    android:orientation="horizontal"
    android:padding="5dip" >

    <!--  ListRow Left side Thumbnail image -->
    <LinearLayout android:id="@+id/thumbnail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="3dip"
        android:layout_alignParentLeft="true"
        android:background="@drawable/image_bg"
        android:layout_marginRight="5dip">

        <ImageView
            android:id="@+id/list_image"
            android:layout_width="50dip"
            android:layout_height="50dip"
            android:src="@drawable/icon"/>

    </LinearLayout>

    <!-- Device Address -->
    <TextView
        android:id="@+id/tvwDeviceAddress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/thumbnail"
        android:layout_toRightOf="@+id/thumbnail"
        android:textColor="#040404"
        android:typeface="sans"
        android:textSize="15dip"
        android:textStyle="bold"/>

    <!-- Display Name -->
    <TextView
        android:id="@+id/tvwDisplayName"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/tvwDeviceAddress"
        android:textColor="#343434"
        android:textSize="10dip"
        android:layout_marginTop="1dip"
        android:layout_toRightOf="@+id/thumbnail"/>


</RelativeLayout>

Adapter:

    private class LazyAdapter extends BaseAdapter {

    private Activity activity;
    private ArrayList<MPGDeviceDetails> data;
    private LayoutInflater inflater=null;

    public LazyAdapter(Activity a, ArrayList<MPGDeviceDetails> d) {
        activity = a;
        data=d;
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public int getCount() {
        return data.size();
    }

    public Object getItem(int position) {
        return position;
    }

    public long getItemId(int position) {
        return position;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;
        Log.e("MPG","Position = " + position + ".  ConvertView = " + convertView);
        if(convertView==null)
            vi = inflater.inflate(R.layout.device_name, null);

        TextView address = (TextView)vi.findViewById(R.id.tvwDeviceAddress); // Device Address
        TextView name = (TextView)vi.findViewById(R.id.tvwDisplayName); // Display name
        ImageView thumb_image=(ImageView)vi.findViewById(R.id.list_image); // thumb image



        address.setText(data.get(position).deviceAddress);
        name.setText(data.get(position).getDisplayName());
        Bitmap photo = data.get(position).getContactPhoto();
        if (photo != null)
            thumb_image.setImageBitmap(photo);


        return vi;
    }
}

Usage:

    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Setup the window
    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
    setContentView(R.layout.device_list);

    // Set result CANCELED incase the user backs out
    setResult(Activity.RESULT_CANCELED);

    // Initialize the button to perform device discovery
    Button scanButton = (Button) findViewById(R.id.button_scan);
    scanButton.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            doDiscovery();
            v.setVisibility(View.GONE);
        }
    });

    // Initialize array adapters. One for already paired devices and
    // one for newly discovered devices


    // Find and set up the ListView for paired devices
    pairedListView = (ListView) findViewById(R.id.paired_devices);
    pairedDevicesList = new ArrayList<MPGDeviceDetails>();
    pairedListView.setAdapter((mPairedDevicesArrayAdapter = new LazyAdapter(this,pairedDevicesList)));
    pairedListView.setOnItemClickListener(mDeviceClickListener);
    registerForContextMenu(pairedListView);

    // Get the local Bluetooth adapter
    mBtAdapter = BluetoothAdapter.getDefaultAdapter();

    // Get a set of currently paired devices
    Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();

    // If there are paired devices, add each one to the ArrayAdapter
    if (pairedDevices.size() > 0) {
        findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);
        for (BluetoothDevice device : pairedDevices) {
          pairedDevicesList.add(MPGDeviceDetailsControl.getDeviceDetails(this, device.getAddress(), device.getName()));
        }
    } 

}

MPGDeviceDetails is an object that holds all the data about a specific device.

This is the output from the "debug" command:

03-27 10:03:30.730: E/MPG(2841): Position = 0.  ConvertView = null.
03-27 10:03:30.742: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@4062d608. 
03-27 10:03:30.746: E/MPG(2841): Position = 0.  ConvertView = null. 
03-27 10:03:30.750: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@40628d78. 
03-27 10:03:30.750: E/MPG(2841): Position = 0.  ConvertView = android.widget.RelativeLayout@4062d608. 
03-27 10:03:30.753: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@4062d608. 
03-27 10:03:30.753: E/MPG(2841): Position = 0.  ConvertView = android.widget.RelativeLayout@40628d78. 
03-27 10:03:30.753: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@40628d78. 
03-27 10:03:30.761: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@4062d608. 
03-27 10:03:30.761: E/MPG(2841): Position = 0.  ConvertView = null. 
03-27 10:03:30.769: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@40628d78. 
03-27 10:03:30.769: E/MPG(2841): Position = 0.  ConvertView = null. 
03-27 10:03:30.777: E/MPG(2841): Position = 0.  ConvertView = null. 
03-27 10:03:30.781: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@406d4af8. 
03-27 10:03:30.781: E/MPG(2841): Position = 0.  ConvertView = null. 
03-27 10:03:30.785: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@40694970. 
03-27 10:03:30.789: E/MPG(2841): Position = 0.  ConvertView = android.widget.RelativeLayout@406d4af8. 
03-27 10:03:30.789: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@406d4af8. 
03-27 10:03:30.789: E/MPG(2841): Position = 0.  ConvertView = android.widget.RelativeLayout@40694970. 
03-27 10:03:30.792: E/MPG(2841): Position = 1.  ConvertView = android.widget.RelativeLayout@40694970.

This is what the screen looks like: enter image description here

Funny thing is that, whilst all 4 buttons work, the context-menu only works for the first two!

why don't you post some code so we can figure out what is going wrong — dymmeh, Mar 26 '12 at 16:07
`the first call for each row in the data should get a null value in currentView.` This is incorrect. Android may use a previously use view for any row past the first one, and often does. Simply reuse the given view by changing its content. — njzk2, Mar 26 '12 at 16:11
Added thr code. Hopefully someone can help me please. Need to show it to a potential employer. — theblitz, Mar 28 '12 at 10:53

score 2 · Accepted Answer · answered Mar 29 '12 at 08:55

2

Try calling notifyDataSetChanged() on your adapter when you've finished filling pairedDevicesList:

if (pairedDevices.size() > 0) {
    findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE);
    for (BluetoothDevice device : pairedDevices) {
        pairedDevicesList.add(MPGDeviceDetailsControl.getDeviceDetails(this, device.getAddress(), device.getName()));
    }
}
((BaseAdapder)getListAdapter()).notifyDataSetChanged();

Or create adapter after filling pairedDevicesList.

Also try stating that your adapter's data has stable ids:

@Override
public boolean hasStableIds() {
    return true;
}

answered Mar 29 '12 at 08:55

a.ch.

8,285
5
40
53

1

Perhaps, you show `` somehow. Try removing it from your layout for a while. – a.ch. Mar 29 '12 at 10:58
Perfect! Doing that pointed me to the mistake: newDevicesListView.setAdapter(new LazyAdapter(this,pairedDevicesList)); Connected the wrong list to the View. – theblitz Mar 29 '12 at 11:26
So what you connected to the list now.. Have you replaced newDevicesListView.setAdapter(new LazyAdapter(this,pairedDevicesList)); – Daya Aug 07 '14 at 13:02

score 0 · Answer 2 · edited May 23 '17 at 12:24

0

In general, besides regular getView calls for each item(s), it is called about 3 times more because it needs to calculate measurements for the views for scrollbar size, layout, etc. Regarding the duplicate rows, i think you should paste your code. You might be doing something else wrong.

For more info, view this and read this

edited May 23 '17 at 12:24

Community

1
1

answered Mar 26 '12 at 16:16

waqaslam

67,549
16
165
178

score 0 · Answer 3 · answered Mar 26 '12 at 16:20

The currentView value should be used to optimization issues. Android propose to reuse views to save the memory and more quicker response.

When yor currentView isn't null then you can use it to display current item.
Take a look at example:

public View getView(int position, View convertView, ViewGroup parent) {
    View v = convertView;
    if (v == null) {
        // we can't reuse view and must read it from layout
        LayoutInflater vi = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        v = vi.inflate(R.layout.whatever, null);
    }

   // ... use v as view for row
}

score 0 · Answer 4 · answered Mar 29 '12 at 07:24

0

You just need to clear the ArrayList before adding values to it.

here in your if condition

if (pairedDevices.size() > 0) { 
 pairedDevicesList.clear();
 // other code as it is
}

also you can put one log before you clear the ArrayList.

Log.i("Size","ArrayList Size = "+pairedDevicesList.size());

So you will get more idea.

answered Mar 29 '12 at 07:24

MKJParekh

34,073
11
87
98

Still no good. Shows it as empty before I fill it and then having 2 rows after I fill. – theblitz Mar 29 '12 at 09:02

Rows being repeated in ListView

4 Answers4

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