Im new to android programming, the current architecture of my application is a Main Activity with a Fragment that fills the display. I am trying to create an ExpandableListView inside the Fragment which also fills the display. Everything works as i am expecting it, i think, however I cannot populate either the Child View or Group View.
In my Fragment Java class file i have;
#Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
ExpandableListView lv = (ExpandableListView) getView().findViewById(R.id.list);
lv.setAdapter(new ParentLevel(null));
}
ParentLevel which extends BaseExpandableListAdapter has;
#Override
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent)
{
return convertView;
}
convertView returns null, but parent returns the ExpandableListView in my layout file.
I'm not sure how to work with this or what to do next, if i wanted to just have a simple TextView, for a title, and a the group arrow what would i do?
I plan to use an enum for the data, which I am already inspecting for getGroupCount() and getChildCount()
I was able to solve my problem with this peice of code;
private final LayoutInflater inf;
private FragmentActivity activity;
public ParentLevel(FragmentActivity act, MenuItem current) {
activity = act;
inf = LayoutInflater.from(act);
};
public View getGroupView(int groupPosition, boolean isExpanded,
View convertView, ViewGroup parent)
{
ViewHolder holder;
if (convertView == null) {
convertView = inf.inflate(R.layout.expandable_list_item, parent, false);
holder = new ViewHolder();
holder.text = (TextView) convertView.findViewById(R.id.text);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.text.setText(activity.getString(siblings.get(groupPosition).getName()));
return convertView;
}
and this class;
private class ViewHolder {
TextView text;
}
Related
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
}
i have an extended baseadapter class which i'm using for populating listview.
i want to change visibility of an element in another layout file(parent file containing listview element) but i'm unable to find a suitable solution.
i tried setting second inflater, executing another class and in fragment but to no avail. however click is detected fine since i'm able to log that in console
convertView = layoutInflater.inflate(R.layout.list_main, null);
final View convertView1 = layoutInflater.inflate(R.layout.tab_fragment_1, null);
that wont work obviously because we could return only one view so i tried declaring another class but still same result
for some reason i'm unable to register click in mainactivity. even that could help
gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
System.out.println("ArrayList Of Vssalues :");
}
});
baseadapter getview class
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = layoutInflater.inflate(R.layout.list_main, null);
final View convertView1 = layoutInflater.inflate(R.layout.tab_fragment_1, null);
final RelativeLayout calendartoshow = (RelativeLayout) row.findViewById(R.id.calendarlay);
final RelativeLayout list_menu = (RelativeLayout) convertView.findViewById(R.id.list_menu);
Button list_but = (Button) list_menu.findViewById(R.id.book_button);
holder = new ViewHolder();
//getView1();
holder.icon = (ImageView)convertView.findViewById(R.id.image);
holder.icon.setImageResource(listData[position]);
holder.text = (TextView)convertView.findViewById(R.id.textv);
final Button holder_but = (Button)convertView.findViewById(R.id.book_button);
holder_but.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
calendartoshow.setVisibility(View.VISIBLE);
System.out.println("ArrayLissst Of Values :");
//new clickclass();
// getView1(position,convertView1,parent);
}
});
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.text.setText(TEXTS[position]);
return convertView;
}
i'm facing a problem which is, when i toggle switch it's works for only last item of listview. It doesn't matter which switch i toggle. I research other asked questions but i couldn't figure it out.
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
LayoutInflater inflater = LayoutInflater.from(getContext());
View customView = inflater.inflate(R.layout.row, parent, false);
String allData = getItem(position);
final Switch status = (Switch) customView.findViewById(R.id.switchStatus);
status.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
Toast.makeText(getContext(),"selectid",Toast.LENGTH_LONG).show();
}
});
return customView;
}
You can see my adapter activiy in here.
public class adapter_test extends ArrayAdapter<String> {
public adapter_allservicerecords(Context context, String[] data){
super(context, R.layout.row, data);
}
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
LayoutInflater inflater = LayoutInflater.from(getContext());
View customView = inflater.inflate(R.layout.row, parent, false);
String allData = getItem(position);
try {
if(!all_data.isEmpty()) {
JSONObject jsonRowData = new JSONObject(all_data);
try {
text.setText(jsonRowData.getString("TITLE"));
} catch (Exception e) {
e.printStackTrace();
}
}
} catch (Exception e) {
Log.e("FAILED", "Json parsing error: " + e.getMessage());
}
return customView;
}
}
The solution to the problem is you have to instead of making your data as a String, you should instead change it into something that would represent each row.
For example you can set this class to represent your row:
class Item {
String data;
boolean toggled;
public Item(String data) {
this.data = data;
}
public void setToggled(boolean toggle) {
toggled = toggle;
}
}
Your data source now must not be Strings, so you should instead have your List as List and you can easily add your strings to the list by passing on new Item("THE STRING DATA HERE"); when adding data to the list.
So instead of
String allData = getItem(position);
you would use
Item item = getItem(position);
then on the getView would look something like this:
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
LayoutInflater inflater = LayoutInflater.from(getContext());
View customView = inflater.inflate(R.layout.row, parent, false);
Item item = getItem(position);
final Switch status = (Switch) customView.findViewById(R.id.switchStatus);
status.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
// here we change the value of the item which is referring to the specific index in the array returned by getItems()
item.setToggled(isChecked);
Toast.makeText(getContext(),"selectid",Toast.LENGTH_LONG).show();
}
});
// here we get what the latest value of the switch is
status.setChecked(item.toggled);
return customView;
}
Make sure you also change your data source into a data structure/list that represents somewhat like List or anything similar on which you decide to use.
BONUS TIP:
It is recommended to use a ViewHolder to hold your View and for efficient recycling of instances.
class ViewHolder {
Switch statusSwitch;
View customView;
}
Then to use that in the getView() part you can easily.
You actually don't have to create a new instance of the view since convertView or the second parameter of the method represents the view that could be reused or instantiated if null.
Heterogeneous lists can specify their number of view types, so that this View is always of the right type, so you are recommended to use that.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = LayoutInflater.from(getContext());
ViewHolder holder = null;
Item item = getItem(position);
if (convertView == null) { // instantiate if not yet instantiated
convertView = inflater.inflate(R.layout.supplies_list_item, null);
holder.statusSwitch = (Switch) convertView.findViewById(R.id.switchStatus);
}
else {
holder = (ViewHolder) convertView.getTag();
}
// you could set the values/ listeners here
holder.statusSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {
item.setToggled(isChecked);
Toast.makeText(getContext(),"selectid",Toast.LENGTH_LONG).show();
}
});
holder.statusSwitch.setChecked(item.toggled);
return convertView;
}
I am getting following warning in eclipse:
Unconditional layout inflation from view adapter: Should use View Holder pattern (use recycled view passed into this method as the second parameter) for smoother scrolling.
on:
convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false);
I have a base adapter with a CheckBox implemented and I have added a tag to make the CheckBox work.
Here is the code:
public View getView(final int position, View convertView, ViewGroup parent)
{
ViewHolder mViewHolder;
mViewHolder = new ViewHolder();
LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false);
mViewHolder.cb = (CheckBox) convertView.findViewById(R.id.checkBox);
convertView.setTag(mViewHolder);
if (InviteFriends.isChecked[position] == true)
{
mViewHolder.cb.setChecked(true);
}
else
{
mViewHolder.cb.setChecked(false);
}
mViewHolder.cb.setOnCheckedChangeListener(new OnCheckedChangeListener()
{
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean ischecked)
{
if (buttonView.isChecked())
{
InviteFriends.isChecked[position] = true;
}
else
{
InviteFriends.isChecked[position] = false;
}
}
});
TextView friendsname = (TextView) convertView.findViewById(R.id.friendsName); // title
ImageView thumb_image = (ImageView) convertView.findViewById(R.id.list_image); // thumb image
HashMap<String, String> song = new HashMap<String, String>();
song = data.get(position);
// Setting all values in listview
friendsname.setText(song.get(InviteFriends.KEY_DISPLAY_NAME));
imageLoader.DisplayImage(song.get(InviteFriends.KEY_IMAGEPROFILE_URL), thumb_image);
return convertView;
}
The results are coming up properly. How do I fix this warning? I am not able to get a solution for this yet?
Thanks!
Try this
static class ViewHolder {
private TextView friendsname;
private ImageView thumb_image;
private CheckBox cb;
}
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder mViewHolder = null;
HashMap<String, String> song = null;
if (convertView == null) {
song = new HashMap <String, String>();
mViewHolder = new ViewHolder();
LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false);
mViewHolder.friendsname = (TextView) convertView.findViewById(R.id.friendsName); // title
mViewHolder.thumb_image = (ImageView) convertView.findViewById(R.id.list_image); // thumb image
mViewHolder.cb = (CheckBox) convertView.findViewById(R.id.checkBox);
convertView.setTag(mViewHolder);
mViewHolder.cb.setTag(data.get(position));
mViewHolder.cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean ischecked) {
InviteFriends.isChecked[position] = buttonView.isChecked();
}
});
} else {
mViewHolder = (ViewHolder) convertView.getTag();
}
song = mViewHolder.cb.getTag();
mViewHolder.friendsname.setText(song.get(InviteFriends.KEY_DISPLAY_NAME));
mViewHolder.imageLoader.DisplayImage(song.get(InviteFriends.KEY_IMAGEPROFILE_URL), thumb_image);
mViewHolder.cb.setChecked(InviteFriends.isChecked[position]);
return convertView;
}
you should init the convert view only if it is null
these lines
LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false);
// [...] the rest of initialization part
// [...] some changes that must be done at refresh
return convertView;
should look like this:
if (convertView == null) {
LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false);
// [...] the rest of initialization part
}
// [...] some changes that must be done at refresh
return convertView;
the goal is to recycle the already existing view in that list, not to init it each time you display it when scrolling the list for example.
Unconditional layout inflation from view adapter: Should use View Holder pattern (use recycled view passed into this method as the second parameter) for smoother scrolling.
It means that you need to use View Holder pattern in your Adapter. The point of using View Holder is to reusing the views because inflating and using findViewById are slow.
When you're using the following code:
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder mViewHolder;
mViewHolder = new ViewHolder();
LayoutInflater vi = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false);
mViewHolder.cb = (CheckBox) convertView.findViewById(R.id.checkBox);
convertView.setTag(mViewHolder);
...
return convertView;
}
you're not reusing the views but instead you always create new views.
You need to change your code to something like this (please check the comment):
// class for holding the cached view
static class ViewHolder {
TextView tvFriendsName;
ImageView imvThumbImage;
CheckBox cbInviteFriend;
}
public View getView(final int position, View convertView, ViewGroup parent) {
// holder of the views to be reused.
ViewHolder viewHolder;
// get data based on the position
HashMap<String, String> song = data.get(position);
// if no previous views found
if (convertView == null) {
// create the container ViewHolder
viewHolder = new ViewHolder();
// inflate the views from layout for the new row
LayoutInflater inflater = LayoutInflater.from(parent.getContext());
convertView = inflater.inflate(R.layout.rowlayout, parent, false);
// set the view to the ViewHolder.
viewHolder.cbInviteFriend = convertView.findViewById(R.id.checkBox);
viewHolder.tvFriendsName = convertView.findViewById(R.id.friendsName);
viewHolder.imvThumbImage = convertView.findViewById(R.id.list_image);
// save the viewHolder to be reused later.
convertView.setTag(viewHolder);
} else {
// there is already ViewHolder, reuse it.
viewHolder = (ViewHolder) convertView.getTag();
}
// now we can set populate the data via the ViewHolder into views
viewHolder.tvFriendsName.setText(song.get(InviteFriends.KEY_DISPLAY_NAME));
imageLoader.DisplayImage(song.get(InviteFriends.KEY_IMAGEPROFILE_URL), viewHolder.imvThumbImage);
viewHolder.cbInviteFriend.isChecked(InviteFriends.isChecked[position]);
return convertView;
}
My suggestion is try to use convertView = vi.inflate(R.layout.activity_friend_list_row, null); insted of convertView = vi.inflate(R.layout.activity_friend_list_row, parent, false); this may help you.
:-
okey.. insted of accessing like this TextView friendsname = (TextView) convertView.findViewById(R.id.friendsName); // title
ImageView thumb_image = (ImageView) convertView.findViewById(R.id.list_image); // thumb image
you have to use viewholder class in your adapter
for example
static class ViewHolder {
public TextView text;
public ImageView image;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View rowView = convertView;
// reuse views
if (rowView == null) {
LayoutInflater inflater = context.getLayoutInflater();
rowView = inflater.inflate(R.layout.rowlayout, null);
// configure view holder
ViewHolder viewHolder = new ViewHolder();
viewHolder.text = (TextView) rowView.findViewById(R.id.TextView01);
viewHolder.image = (ImageView) rowView
.findViewById(R.id.ImageView01);
rowView.setTag(viewHolder);
}
// fill data
ViewHolder holder = (ViewHolder) rowView.getTag();
String s = names[position];
holder.text.setText(s);
if (s.startsWith("Windows7") || s.startsWith("iPhone")
|| s.startsWith("Solaris")) {
holder.image.setImageResource(R.drawable.no);
} else {
holder.image.setImageResource(R.drawable.ok);
}
return rowView;
}
What i have done is created a BaseSpinnerAdapter class and reusing it if needed
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.BaseAdapter
import androidx.annotation.LayoutRes
/**
* #param T Model class
* #param VH ViewHolder class, which holds the view to reuse it
* */
abstract class BaseSpinnerAdapter<T, VH>(context: Context?, private val items: ArrayList<T>) :
BaseAdapter() {
private var inflater: LayoutInflater = LayoutInflater.from(context)
/** use viewHolder pattern to reusing the views
* #param p0 current view position
* #param p1
* #param viewGroup
* */
override fun getView(p0: Int, p1: View?, viewGroup: ViewGroup?): View {
var pClone = p1
val viewHolder: VH
if (pClone == null) {
pClone = inflater.inflate(setSpinnerItemLayout(), viewGroup, false)
viewHolder = createViewHolder(pClone)
pClone?.tag = viewHolder
} else {
viewHolder = pClone.tag as VH
}
getView(viewHolder, p0)
return pClone!!
}
override fun getItem(p0: Int): T {
return items[p0]
}
override fun getItemId(p0: Int): Long {
return p0.toLong()
}
override fun getCount(): Int {
return items.size
}
#LayoutRes
abstract fun setSpinnerItemLayout(): Int
abstract fun getView(viewHolder: VH, position: Int)
abstract fun createViewHolder(view: View?): VH
}
Here is an example How you can use BaseSpinnerAdapter in your implementation. I believe that there is no need to detail out the code description.
class SpinnerImplAdapter(context: Context?, private val items: ArrayList<AnyModelClass>) : BaseSpinnerAdapter<AnyModelClass, SpinnerImplAdapter.ViewHolderImp>(context, items) {
override fun setSpinnerItemLayout(): Int {
return R.layout.spinner_item
}
override fun createViewHolder(view: View?): ViewHolderImp {
return ViewHolderImp(view)
}
override fun getView(viewHolder: ViewHolderImp, position: Int) {
val model = items[position]
viewHolder.textView?.text = "" // model.etc get anything you want
}
/**
* I have used kotlin extension to get the viewId,
* if you are not using then simply call the view.findViewById(R.id.yourView)
* */
class ViewHolderImp(view: View?) {
val textView: TextView? = view?.textView
}
}
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.