I have a custom listview with a button to add more elements
but when I add and element the app crash, but when I restart I find that the element is added, (rarely it doesn't crash)
And i
I use custom adapter
class CustomAdapter extends BaseAdapter {
ArrayList<ListItem> listItems = new ArrayList<ListItem>();
CustomAdapter(ArrayList<ListItem> list){
this.listItems = list;
}
#Override
public int getCount() {
return listItems.size();
}
#Override
public Object getItem(int position) {
return listItems.get(position).name;
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int i, View convertView, ViewGroup parent) {
LayoutInflater inflater = getLayoutInflater();
View view = inflater.inflate(R.layout.list_item,null);
TextView name = (TextView) view.findViewById(R.id.name);
TextView lastm = (TextView) view.findViewById(R.id.last);
TextView time = (TextView) view.findViewById(R.id.time);
CircleImageView pic= (CircleImageView) view.findViewById(R.id.pic);
name.setText(listItems.get(i).name);
lastm.setText(listItems.get(i).lastm);
time.setText(listItems.get(i).time);
Bitmap bmp = BitmapFactory.decodeByteArray(listItems.get(i).pic,0,listItems.get(i).pic.length);
pic.setImageBitmap(bmp);
return view;
}
}
and when I add an element the app crashs
add.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
EditText editText=(EditText) mView.findViewById(R.id.name);
String name=editText.getText().toString();
boolean result=myDataBase.insertData(imageViewToByte(img),name,"no messages yet","");
if (result) {
Toast.makeText(Main2Activity.this, "Saved in DATABASE", Toast.LENGTH_SHORT).show();
viewLastData();
dialog.dismiss();
}
If your ListView lags it's because you used wrap_content for the listView's layout_height. It forces your ListView to count all the items inside and it has a huge performance impact.
So replace wrap_content by match_parent to avoid those lags.
EDIT: Use a ViewHolder pattern too in your Adapter, see this link.
Here is an example:
// ViewHolder Pattern
private static class ViewHolder {
TextView name, status;
}
#Override #NonNull
public View getView(int position, View convertView, #NonNull ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
LayoutInflater vi = LayoutInflater.from(getContext());
convertView = vi.inflate(R.layout.list_item, parent, false);
holder = new ViewHolder();
holder.name = (TextView) convertView.findViewById(R.id.text_name);
holder.status = (TextView) convertView.findViewById(R.id.another_text);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
// Then do the other stuff with your item
// to populate your listView
// ...
return convertView
}
Related
I have created a ListView of items that each one of them looks as follows:
In simplified code, It looks like this:
public class MyBAdapter extends ArrayAdapter {
private static class ViewHolder {
public ImageButton ib_Delete;
public ToggleButton tb_Status;
}
public MyBAdapter(Context context, ArrayList<MyB> aB) {
super(context, 0, aB);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
final MyB b = getItem(position);
ViewHolder viewHolder;
if (convertView == null) {
viewHolder = new ViewHolder();
LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate( R.layout.item_b_myb, parent, false);
viewHolder.ib_DeleteB = convertView.findViewById( R.id.ib_DeleteB );
viewHolder.tb_Status = convertView.findViewById( R.id.tb_Status );
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
return convertView;
}
}
Now, I had like that once a user clicks on the ToggleButton of on the x button, that it will remove this item from the list and that the view will be updated on this screen.
How can I do it?
I saw that for this case notifyDataSetChanged() won't work.
Basically what I'm trying to do is to refresh the list without calling again the activity.
Thank you
You can try like this:
public static class MyBAdapter extends ArrayAdapter {
private ArrayList<String> aB;
private class ViewHolder {
public ImageButton ib_Delete;
public ToggleButton tb_Status;
public TextView text;
}
public MyBAdapter(Context context, ArrayList<String> aB) {
super(context,0, aB);
this.aB = aB;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if (convertView == null) {
viewHolder = new ViewHolder();
LayoutInflater inflater = (LayoutInflater)getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate( R.layout.item_b_myb, parent, false);
viewHolder.ib_Delete = convertView.findViewById( R.id.ib_DeleteB );
viewHolder.tb_Status = convertView.findViewById( R.id.tb_Status );
viewHolder.text = convertView.findViewById( R.id.text );
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
viewHolder.tb_Status.setChecked(false);
}
viewHolder.text.setText(aB.get(position));
viewHolder.ib_Delete.setTag(position);
viewHolder.ib_Delete.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if(viewHolder.tb_Status.isChecked()){
delete((Integer)view.getTag());
}
}
});
return convertView;
}
private void delete(int position) {
aB.remove(position);
notifyDataSetChanged();
}
#Override
public int getCount() {
return aB.size();
}
}
I wanted to show the image only at the selected row from listview. Here is the code:
private class ListAdapter extends BaseAdapter {
LayoutInflater inflater;
ViewHolder viewHolder;
public ListAdapter(Context context) {
inflater = LayoutInflater.from(context);
}
public int getCount() {
return attendeeList.size();
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = inflater.inflate(R.layout.attendee_listview_row,
null);
viewHolder = new ViewHolder();
viewHolder.txt_dName = (TextView) convertView
.findViewById(R.id.txtDisplayName);
viewHolder.txt_dAddr = (TextView) convertView
.findViewById(R.id.txtDisplayAddr);
viewHolder.txt_dtelNo = (TextView) convertView
.findViewById(R.id.txtDisplayTelNo);
viewHolder.btn_scan = (ImageView) convertView.findViewById(R.id.btnScan);
viewHolder.registered_tag = (ImageView) convertView.findViewById(R.id.ivRegisteredTag);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.txt_dName.setText(attendeeList.get(position)
.getAccountName().trim());
viewHolder.txt_dAddr.setText(attendeeList.get(position)
.getAttendeeAddr().trim());
viewHolder.txt_dtelNo.setText("Tel no: "
+ attendeeList.get(position).getTelNo().trim());
viewHolder.btn_scan.setOnClickListener(new OnClickListener(){
public void onClick(View v){
viewHolder.registered_tag.setVisibility(View.VISIBLE);
Intent intent = new Intent(
"com.google.zxing.client.android.SCAN");
intent.putExtra("SCAN_MODE", "QR_CODE_MODE");
startActivityForResult(intent, 0);
}
});
return convertView;
}
}
With these code, I am trying to show the registered_tag upon btn_scan onClick. However, the image is not really showing at the selected row. It shows at other row instead.
Any ideas? Thanks in advance.
Probably you are getting last row image change when clicking on any row because viewHolder will contain last row view when getView called. Use setTag and getTag method of viewHolder.btn_scan view to save and get selected row view in onClick method:
viewHolder.btn_scan.setTag(viewHolder);
viewHolder.btn_scan.setOnClickListener(new OnClickListener(){
public void onClick(View v){
ViewHolder selectedViewHolder=(ViewHolder)v.getTag();
selectedViewHolder.registered_tag.setVisibility(View.VISIBLE);
...
}
});
I have made an Listview populated with list_row_layout.xml(which is populated with json serializable class), i have clickable textview and onclick changing text from "Accept" to "Accepted". But when i click it on first listview item, another textview listview items below are changing. Here's some photos to descibe you better
Activity class
feedListView.setAdapter(new CustomListAdapter(this, feedList));
adapter class
public class CustomListAdapter extends BaseAdapter
{
private ArrayList<FeedItem> listData;
private LayoutInflater layoutInflater;
private Context mContext;
public CustomListAdapter(Context context, ArrayList<FeedItem> listData)
{
this.listData = listData;
layoutInflater = LayoutInflater.from(context);
mContext = context;
}
#Override
public int getCount()
{
return listData.size();
}
#Override
public Object getItem(int position)
{
return listData.get(position);
}
#Override
public long getItemId(int position)
{
return position;
}
public View getView(int position, View convertView, ViewGroup parent)
{
final ViewHolder holder;
if (convertView == null)
{
convertView = layoutInflater.inflate(R.layout.list_row_layout, null);
holder = new ViewHolder();
holder.headlineView = (TextView)convertView.findViewById(R.id.title);
holder.reportedDateView = (TextView) convertView.findViewById(R.id.confid);
holder.approve = (TextView) convertView.findViewById(R.id.approveTV);
holder.approve.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View argView)
{
holder.approve.setText("accepted");
}
}
);
convertView.setTag(holder);
}
else
{
holder = (ViewHolder) convertView.getTag();
}
FeedItem newsItem = listData.get(position);
holder.headlineView.setText(Html.fromHtml(newsItem.getTitle()));
holder.reportedDateView.setText(Html.fromHtml(newsItem.getContent()));
holder.approve.setTag(newsItem);
return convertView;
}
static class ViewHolder
{
TextView approve;
TextView headlineView;
TextView reportedDateView;
ImageView imageView;
}
}
textview code
<TextView
android:id="#id/approveTV"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_marginRight="5dp"
android:background="#drawable/pressed"
android:gravity="fill"
android:text="Accept"
android:clickable="true"
android:textColor="#0D98BA"
android:textSize="17sp" />
You have to write some tracking position functionality which remember the position which you have changed and make sure that only text of position changed .
you must set id to each row, and save it in one array,like integer and when you click on one row you must change the value of that, and in changing text or anything you must check the value of that row,if 0 then set default and if 1 then so what you want: my idea is create int[] with length of that is size of your list,
first you must define you int[] like below and set to zero every index.
int[] selected = new int[listData.getsize()]
something like this in getview:
holder.approve.setId(Html.fromHtml(newsItem.getId());
and after else statement in getView:
if (selected[position] == 0)
{
// set default
}
else
{
// any changing that you want
}
and in onClick:
selected[holder.approve.getId()] = 1;
// any change that you want
Try the below code:-
public View getView(final int position, View convertView, ViewGroup parent)
{
final ViewHolder holder;
if (convertView == null)
{
holder = new ViewHolder();
convertView = layoutInflater.inflate(R.layout.list_row_layout, null);
holder.headlineView = (TextView)convertView.findViewById(R.id.title);
holder.reportedDateView = (TextView) convertView.findViewById(R.id.confid);
holder.approve = (TextView) convertView.findViewById(R.id.approveTV);
convertView.setTag(holder);
}
else
{
holder = (ViewHolder) convertView.getTag();
}
FeedItem newsItem = listData.get(position);
holder.headlineView.setText(Html.fromHtml(newsItem.getTitle()));
holder.reportedDateView.setText(Html.fromHtml(newsItem.getContent()));
holder.approve.setOnClickListener(new OnClickListener()
{
#Override
public void onClick(View argView)
{
holder.approve.setText("accepted");
}
}
);
return convertView;
}
Thanks!!
my images get shuffled or changed when i scroll in list view.......
Images get shuffled when i scroll down and keep on changing own its own...............
public class CustomListAdapter extends BaseAdapter {
private ArrayList<NewsItem> listData;
private LayoutInflater layoutInflater;
public CustomListAdapter(Context context, ArrayList<NewsItem> listData) {
this.listData = listData;
layoutInflater = LayoutInflater.from(context);
}
#Override
public int getCount() {
return listData.size();
}
#Override
public Object getItem(int position) {
return listData.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.activity_list_search, null);
holder = new ViewHolder();
holder.headlineView = (TextView) convertView.findViewById(R.id.title);
holder.reporterNameView = (TextView) convertView.findViewById(R.id.reporter);
holder.reportedDateView = (TextView) convertView.findViewById(R.id.date);
holder.imageView = (ImageView) convertView.findViewById(R.id.thumbImage);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
NewsItem newsItem = (NewsItem) listData.get(position);
holder.headlineView.setText(newsItem.getHeadline());
holder.reporterNameView.setText("Model: " + newsItem.getReporterName());
holder.reportedDateView.setText(newsItem.getDate());
if (holder.imageView != null) {
new ImageDownloaderTask(holder.imageView).execute(newsItem.getUrl());
}
return convertView;
}
static class ViewHolder {
TextView headlineView;
TextView reporterNameView;
TextView reportedDateView;
ImageView imageView;
}
}
The problem is very generic for new Android developers.
Your ImageDownloaderTask should take care of whether the downloaded image should still be posted on screen.
For example, after ImageDownloaderTask finishes one image downloading task (e.g. for index 15), it should make sure the 15th item is still displaying on screen. Since ListView is reusing all the item views, if you directly set the bit map to the original referenced view, your imageview will be shuffled.
Is it possible to get an item view based on its position in the adapter and not in the visible views in the ListView?
I am aware of functions like getChildAt() and getItemIdAtPosition() however they provide information based on the visible views inside ListView. I am also aware that Android recycles views which means that I can only work with the visible views in the ListView.
My objective is to have a universal identifier for each item since I am using CursorAdapter so I don't have to calculate the item's position relative to the visible items.
Here's how I accomplished this. Within my (custom) adapter class:
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = null;
if (convertView == null) {
LayoutInflater inflater = context.getLayoutInflater();
view = inflater.inflate(textViewResourceId, parent, false);
final ViewHolder viewHolder = new ViewHolder();
viewHolder.name = (TextView) view.findViewById(R.id.name);
viewHolder.button = (ImageButton) view.findViewById(R.id.button);
viewHolder.button.setOnClickListener
(new View.OnClickListener() {
#Override
public void onClick(View view) {
int position = (int) viewHolder.button.getTag();
Log.d(TAG, "Position is: " +position);
}
});
view.setTag(viewHolder);
viewHolder.button.setTag(items.get(position));
} else {
view = convertView;
((ViewHolder) view.getTag()).button.setTag(items.get(position));
}
ViewHolder holder = (ViewHolder) view.getTag();
return view;
}
Essentially the trick is to set and retrieve the position index via the setTag and getTag methods. The items variable refers to the ArrayList containing my custom (adapter) objects.
Also see this tutorial for in-depth examples. Let me know if you need me to clarify anything.
See below code:
public static class ViewHolder
{
public TextView nm;
public TextView tnm;
public TextView tr;
public TextView re;
public TextView membercount;
public TextView membernm;
public TextView email;
public TextView phone;
public ImageView ii;
}
class ImageAdapter extends ArrayAdapter<CoordinatorData>
{
private ArrayList<CoordinatorData> items;
public FoodDriveImageLoader imageLoader;
public ImageAdapter(Context context, int textViewResourceId,ArrayList<CoordinatorData> items)
{
super(context, textViewResourceId, items);
this.items = items;
}
public View getView(int position, View convertView, ViewGroup parent)
{
View v = convertView;
ViewHolder holder = null;
if (v == null)
{
try
{
holder=new ViewHolder();
LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
imageLoader = new FoodDriveImageLoader(FoodDriveModule.this);
v = vi.inflate(R.layout.virtual_food_drive_row, null);
//System.out.println("layout is null.......");
holder.nm = (TextView) v.findViewById(R.id.name);
holder.tnm = (TextView) v.findViewById(R.id.teamname);
holder.tr = (TextView) v.findViewById(R.id.target);
holder.re = (TextView) v.findViewById(R.id.received);
holder.membercount = new TextView(FoodDriveModule.this);
holder.membernm = new TextView(FoodDriveModule.this);
holder.email = new TextView(FoodDriveModule.this);
holder.phone = new TextView(FoodDriveModule.this);
holder.ii = (ImageView) v.findViewById(R.id.icon);
v.setTag(holder);
}
catch(Exception e)
{
System.out.println("Excption Caught"+e);
}
}
else
{
holder=(ViewHolder)v.getTag();
}
CoordinatorData co = items.get(position);
holder.nm.setText(co.getName());
holder.tnm.setText(co.getTeamName());
holder.tr.setText(co.getTarget());
holder.re.setText(co.getReceived());
holder.ii.setTag(co.getImage());
imageLoader.DisplayImage(co.getImage(), FoodDriveModule.this , holder.ii);
if (co != null)
{
}
return v;
}
}
A better option is to identify using the data returned by the CursorAdapter rather than visible views.
For example if your data is in a Array , each data item has a unique index.
Here, Its very short described code, you can simple re-use viewholder pattern to increase listview performance
Write below code in your getview() method
ViewHolder holder = new ViewHolder();
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.skateparklist, null);
holder = new ViewHolder();
holder.headlineView = (TextView) convertView
.findViewById(R.id.textView1);
holder.DistanceView = (TextView) convertView
.findViewById(R.id.textView2);
holder.imgview = (NetworkImageView) convertView
.findViewById(R.id.imgSkatepark);
convertView.setTag(holder); //PLEASE PASS HOLDER AS OBJECT PARAM , CAUSE YOU CAN NOY PASS POSITION IT WILL BE CONFLICT Holder and Integer can not cast
//BECAUSE WE NEED TO REUSE CREATED HOLDER
} else {
holder = (ViewHolder) convertView.getTag();
}
// your controls/UI setup
holder.DistanceView.setText(strDistance);
......
return convertview
Listview lv = (ListView) findViewById(R.id.previewlist);
final BaseAdapter adapter = new PreviewAdapter(this, name, age);
confirm.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
View view = null;
String value;
for (int i = 0; i < adapter.getCount(); i++) {
view = adapter.getView(i, view, lv);
Textview et = (TextView) view.findViewById(R.id.passfare);
value=et.getText().toString();
Toast.makeText(getApplicationContext(), value,
Toast.LENGTH_SHORT).show();
}
}
});