Develop Reference

Do I use ViewHolder correctly? Everithing is worked, but i still have doubts with the ListView optimization with holder recycler

I am just adapting my custom adapter code with ViewHolder so that i can optimize my list view with a recycler, but i am not sure if i do it right.
My view holder class:
public class ViewHolderTask {
int positionHolder;
TextView nameHolder;
TextView timeHolder;
TextView sessionHolder;
TextView dateHolder;
FloatingActionButton mFabTaskHolder;
public ViewHolderTask(View v, int position) {
this.positionHolder = position;
this.nameHolder = v.findViewById(R.id.taskNameText);
this.timeHolder = v.findViewById(R.id.timeTextView);
this.sessionHolder = v.findViewById(R.id.textViewSession);
this.dateHolder = v.findViewById(R.id.dateTextView);
this.mFabTaskHolder = v.findViewById(R.id.myFabTask);
}
My custom adapter class:
#NonNull
#Override
public View getView(int position, #Nullable View convertView, #NonNull ViewGroup parent) {
ViewHolderTask holder;
if(convertView == null){
LayoutInflater inflater = (LayoutInflater) context.getSystemService(
Context.LAYOUT_INFLATER_SERVICE );
convertView = inflater.inflate(R.layout.task_row, parent, false);
holder = new ViewHolderTask(convertView, position);
convertView.setTag(holder);
}else{
holder = (ViewHolderTask) convertView.getTag();
}
Task task = taskArrayList.get(position);
//set the configurations
holder.getTimeHolder().setText(getTimeString(task.getTime()));
holder.getNameHolder().setText(task.getName());
holder.getDateHolder().setText(getDateString(task.getDate()));
holder.getSessionHolder().setText(getSessionString(task.getSession()));
//Set the FAB listener
addFabListener(holder.getmFabTaskHolder(), position);
//set the clicked background
if(TaskActivity.getIsClicked() && TaskActivity.getPositionClicked()-1 == position){
convertView.setBackgroundResource(R.color.backgroundSelectedItem);
}
return convertView;
}
Do I use it right?

Seems to be fine for me other than this portion of the code
//set the clicked background
if(TaskActivity.getIsClicked() && TaskActivity.getPositionClicked()-1 == position){
convertView.setBackgroundResource(R.color.backgroundSelectedItem);
}
You might need to reset the background resource back to default for the item which is not clicked. maybe you have to add "else" part to the "if"

Different Button in List view

I have two ArrayList namely "one" and "two" ["two" is always a sub-set of "one"], And i have a list view which is populating by Arraylist "one". Now am checking condition that if element of "two" is present in "one", then set ImageButton in list view and if not the set Button in list view.
Below is my getView method. Any help or keywords will be appreciated.
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if (convertView == null) {
LayoutInflater inflater = LayoutInflater.from(context);
//HERE HOW TO SWITCH TWO LAYOUTS..
convertView = inflater.inflate(R.layout.invite_row, null);
viewHolder = new ViewHolder();
viewHolder.name = (TextView)convertView.findViewById(R.id.textView6);
viewHolder.text = (TextView) convertView.findViewById(R.id.childTextView);
viewHolder.button = (Button) convertView
.findViewById(R.id.childButton);
Typeface typeFace= Typeface.createFromAsset(context.getAssets(), "fonts/Roboto-Bold.ttf");
viewHolder.name.setTypeface(typeFace);
// viewHolder.button.setBackgroundResource(R.drawable.invitebuttonbackground);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
final String temp = getItem(position);
final String tempname = getItem(position);
viewHolder.name.setText(tempname);
viewHolder.button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (customListner != null) {
customListner.onButtonClickListner(position, temp, tempname);
}
}
});
return convertView;
}

one thing you can do is
View convertView;
if (whatever condition) {
convertView = inflater.inflate(R.layout.invite_row, null);
} else {
convertView = inflater.inflate(R.layout.invite_row_two, null);
}
if you can post your layout , i will have clear undestanding of what you want to doing.

Gridview repeating images but not the text in android

In ImageView, my images are being shuffled but not the text. This is my getView() method:
public View getView(int position, View convertView, ViewGroup parent) {
View v;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) mainActivity.getSystemService( Context.LAYOUT_INFLATER_SERVICE );
v = inflater.inflate(R.layout.item_people, parent, false);
} else {
v = (View) convertView;
}
TextView textView = (TextView) v.findViewById(R.id.name);
ImageView imageView = (ImageView) v.findViewById(R.id.image);
if (list.get(position).getClass() == SearchData.Video.class) {
SearchData.Video video = (SearchData.Video) list.get(position);
textView.setText(video.getVideoName());
if (video.getCoverPicture().length > 0)
imageView.setBackground(mainActivity.Base64toImage(video.getCoverPicture()[0].getImg()));
} else if (list.get(position).getClass() == SearchData.Actor.class) {
SearchData.Actor actor = (SearchData.Actor) list.get(position);
textView.setText(actor.getFirstName());
if (actor.getPicture().length > 0)
imageView.setBackground(mainActivity.Base64toImage(actor.getPicture()[0].getImg()));
}
return v;
}
I am setting image and text of actors. When I scroll down then up the images have shuffled, but not text. Why?

Did you tried the same with ViewHolder
Normally when ever getView() method is called, the gridview/ listview will automatically notified as a change, So that is the reason for your image shuffling s / changing in your gridview.
So, try to implement your Gridview with ViewHolder pattern and avoid those shuffling s / re-orderings
here is the sample code for view holder pattern implementation.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolderItem viewHolder;
// The convertView argument is essentially a "ScrapView" as described is Lucas post
// http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/
// It will have a non-null value when ListView is asking you recycle the row layout.
// So, when convertView is not null, you should simply update its contents instead of inflating a new row layout.
if(convertView==null){
// inflate the layout
LayoutInflater inflater = ((Activity) mContext).getLayoutInflater();
convertView = inflater.inflate(layoutResourceId, parent, false);
// well set up the ViewHolder
viewHolder = new ViewHolderItem();
viewHolder.textViewItem = (TextView) convertView.findViewById(R.id.textViewItem);
// store the holder with the view.
convertView.setTag(viewHolder);
}else{
// we've just avoided calling findViewById() on resource everytime
// just use the viewHolder
viewHolder = (ViewHolderItem) convertView.getTag();
}
// object item based on the position
ObjectItem objectItem = data[position];
// assign values if the object is not null
if(objectItem != null) {
// get the TextView from the ViewHolder and then set the text (item name) and tag (item ID) values
viewHolder.textViewItem.setText(objectItem.itemName);
viewHolder.textViewItem.setTag(objectItem.itemId);
}
return convertView;
}
your ViewHodler should be like this
// ViewHolder.
// caches our TextView
static class ViewHolderItem {
TextView textViewItem;
}
This is not the exactly same to your question, but you can edit the above logic for your way.
Hope it Helps :)

Populating Custom ArrayAdapters

I have made my own CustomArrayAdapter to show list of Brazilian Restaurants. I have overidden the GetView method to make my own custom view.
private class MyAdapter extends ArrayAdapter<String> {
public MyAdapter(Context context, int resource, int textViewResourceId,
String[] strings) {
super(context, resource, textViewResourceId, strings);
// TODO Auto-generated constructor stub
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.list_item, parent,false);
String [] items= getResources().getStringArray(R.array.locations_array);
TextView tv= (TextView) row.findViewById(R.id.textView1);
ImageView iv = (ImageView) row.findViewById(R.id.imageView1);
tv.setText(items[position]);
iv.setImageResource(R.drawable.brazil);
return row;
}
}
Currently this new GetView class is pulling in a text string from a resource xml file and putting it into the list item.
If I wanted to incorporate an array of extra data generated within the app, I assume that I don't do the array generating in the GetView class as this will be recreated each time a new row is made.
Where do I put the code to make the array, and how do I call this data into the GetView code above?

It's worth pointing out that for better performance you should be making use of the convertView variable passed into the getView() method.
The use of convertView allows you to re-use list item views instead of creating new ones which has a heavy performance hit. If you have a large data set or value performance in your app, you would do well to check out the documentation for getView()
Your code would then look something more like this:
...
//it's also worth moving these methods to your constructor so they aren't called every time getView() for better performance
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
String [] items= getResources().getStringArray(R.array.locations_array);
#Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView == null)
convertView = inflater.inflate(R.layout.list_item, parent, false);
TextView tv= (TextView) convertView.findViewById(R.id.textView1);
ImageView iv = (ImageView) convertView.findViewById(R.id.imageView1);
tv.setText(items[position]);
iv.setImageResource(R.drawable.brazil);
return row;
}
...

Building on #CodeDownZero's answer, I highly recommend you adopt the ViewHolder pattern, and definitely recycle your listviews (using convertview).
...
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = null;
if (convertView == null) {
LayoutInflater inflater = (LayoutInflater) getSystemService
(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(textViewResourceId, parent, false);
final ViewHolder viewHolder = new ViewHolder();
viewHolder.tv1 = (TextView) view.findViewById(R.id.textView1);
viewHolder.tv2 = (TextView) view.findViewById(R.id.textView2);
view.setTag(viewHolder);
} else {
view = convertView;
}
ViewHolder holder = (ViewHolder) view.getTag();
MyDataClass data = this.getItem(position);
holder.tv1.setText(data.street);
holder.tv2.setText(data.name);
return view;
}
...
private class ViewHolder {
private TextView tv1;
private TextView tv2;
}

You can base an ArrayAdapter on a custom class instead of string. Here is an example:
public class MyDataClass {
public String street;
public String name;
}
private class MyAdapter extends ArrayAdapter<MyDataClass> {
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View row = inflater.inflate(R.layout.list_item, parent,false);
TextView tv1= (TextView) row.findViewById(R.id.textView1);
TextView tv2= (TextView) row.findViewById(R.id.textView2);
MyDataClass data = this.getItem(position);
tv1.setText(data.street);
tv2.setText(data.name);
return row;
}
}
To populate the Adapter with data you can use this snippet in the OnCreate method of the Activity:
..
MyAdapter adapter = new MyAdapter();
MyDataClass lData = new MyDataClass(); // here was a mistake
lData.name = "MyName";
lData.street = "MyRoad";
adapter.Add(lData);
..
ListView.Adapter=adapter; // where Listview is the Listview

How to create a listview which have a customize look? [duplicate]

Can someone tell me how should am i going to create my listview which look similar [here][1].
Problem: How am i going to fulfill the sort of look and feel in my codes which has an icons, file name, and file size yet at the same time looking clean and simple on each file object as shown in the example in the link [here][2]??
Can someone guide on this matter because i'm rather new in android/java... Thanks

Refer to following url for how to implement custom listview
Update
public static class VideoInfo {
public String name = "";
public String size= "";
public String path = "";//add any more variables of which you want info
}
then where you are creating arraylist i.e getVideoFiles() create object of this class
Declare ArrayList<VideoInfo> videoItems;
private void getVideoFiles(File[] videoList)
{
videoItems = new ArrayList<VideoInfo>();
for (int i = 0; i < videolist.length; i++)
{
File mfile = videoList[i];
String path = mfile.getPath();
path = path.substring(path.lastIndexOf("/", path.indexOf("."));
VideoInfo model = new VideoInfo();
model.name = path;
model.size = mfile.length();
videoItems.add(model);
}
setListAdapter(new ListViewAdapter(this, R.layout.row, videoItems));
}
now in your adapter pass this object of arraylist and how you set variables in listview is already given in link above

Problem 2: And why is my listview
having error when the directory is
empty despite having this to handle
the "empty" in my xml
did you remember to name your listview?:
#id/android:list
And if you could for further helper PLEASE clear up problem 1, so its more clear and concise what you want.
UPDATE
The ID of the listview should be: #id/android:list
The ID of the texview should be: #id/android:empty

You haven't create custom adapter to incorporate the layout into codes listview.
Here is something you can use
private class ListViewAdapter extends ArrayAdapter<Object> {
private ArrayList<Object> items;
public ListViewAdapter(Context context, int textViewResourceId,
ArrayList<Object> items) {
super(context, textViewResourceId, items);
this.items = items;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
Object info = items.get(position);
if (v == null) {
LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.row, null);
}
if (info != null) {
ImageView imView = (ImageView) v.findViewById(R.id.icon);
TextView txtname =(TextView) v.findViewById(R.id.toptext);
TextView txtAddr = (TextView) v.findViewById(R.id.bottomtext);
//set image and set text as you like
}
return v;
}
}
Hope this can help.

First Create the Layout that you want to display for each row in your list then Extend the BaseAdapter class to Customize your Lists. This class contains getView method to replicate the rows in your lists as many times as you want to.
class HighScoreAdapter extends BaseAdapter
{
/* layout inflater to convert your XML layout to View to be rendered in your Each row of Lists.*/
private LayoutInflater minflator = LayoutInflater.from(HighScoreList.this);
ViewHolder holder;
#Override
public Object getItem(int position)
{
return position;
}
#Override
public long getItemId(int position)
{
return position;
}
boolean toRemove = false;
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
/* first time is null */
if (convertView == null )
{
convertView = minflator.inflate(R.layout.highscorelist, null);
holder = new ViewHolder();
holder.rank = (TextView) convertView.findViewById(R.id.user_id);
holder.username = (EditText) convertView.findViewById(R.id.user_nameedit);
holder.time = (TextView) convertView.findViewById(R.id.user_time);
convertView.setTag(holder);
}
else
{
holder = (ViewHolder) convertView.getTag();
}
holder.rank.setText(String.valueOf(position+1)+".");
/* returns the view for next row as layout will be same i.e. this increases the your list's scrolling and working faster even though your list contains thousands of Entry*/
return convertView;
}
/* this class is to make reference to your child views of your layout by using this you can set your child views properties and Listeners acording to your need.*/
class ViewHolder
{
TextView rank;
EditText username;
TextView time;
}
}
I hope this solves your problem completely.. :)

Add this method to your code and if you get any error or Exception please let me know.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
Object info = items.get(position);
if (v == null) {
LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.row, null);
}
if (info != null) {
ImageView imView = (ImageView) v.findViewById(R.id.icon);
TextView txtname =(TextView) v.findViewById(R.id.toptext);
TextView txtAddr = (TextView) v.findViewById(R.id.bottomtext);
//set image and set text as you like
imview.setImageBitmap(IMAGE YOU WANT TO SET AAS ICON);
txtname.setText(FILENAME YOU WANT TO SET);
txtadr,setText(FILESIZE YOU WANT TO SET);
// Better you take each info filename,filesize and icon in a arraylist and set them
}
return v;
}