I am creating a playlist with 2 lines of name and genre, how to I can delete it.
This is MainActivity :
String[] gene, sl;
...
adp = new Adapter(MainActivity.this, gene, sl);
lv.setAdapter(adp);
This is Adapter
public class Adapter extends ArrayAdapter<String> {
private final Activity context;
private final String[] gene;
private final String[] sl;
SharedPreferences preferences;
public Adapter(Activity context, String[] gene ,String[] sl) {
super(context, R.layout.activity_m , gene);
this.context = context;
this.gene = gene;
this.sl = sl;
}
private class ViewHolder{
TextView txtgene, txtsl;
}
#Override
public View getView(final int position, View view, ViewGroup parent) {
ViewHolder holder;
if (view == null) {
LayoutInflater inflater = context.getLayoutInflater();
view = inflater.inflate(R.layout.activity_m, null, true);
holder = new ViewHolder();
holder.txtgene = (TextView) view.findViewById(R.id.txtgene);
holder.txtsl = (TextView) view.findViewById(R.id.txtsl);
view.setTag(holder);
}else{
holder = (ViewHolder) view.getTag();
}
if (gene[position] != null) {
holder.txtgene.setText(gene[position]);
}
holder.txtsl.setText(sl[position]);
return view;
}
}
How to remove an item when you know its exact position ?
Thank !
You are using the ArrayAdapter constructor that takes an array. This in turn will create an immutable List internal to the ArrayAdapter. So, you will not be able to modify your adapter going this route.
Instead, make a new ArrayList from your array and call the ArrayAdapter constructor that takes a List.
So, change the super call in your Adapter constructor to this:
super(context, R.layout.activity_m, new ArrayList<>(Arrays.asList(gene)));
And then, when you want to remove an item given it's position, do this:
adp.remove(getItem(position));
PS: You should consider refactoring your gene and sl arrays into a class and then use it as the type of your List.
Related
I am trying to create my first Custom Adapter to generate a listview for my android app. I am getting my data from an Api call and then process it and store it in an arraylist:-
class Person{
String bioguide;
String image;
String lastname;
String firstname;
String district;
String state;
String party;}
public static ArrayList<Person> personData = new ArrayList<Person>();
Now in the onpostexecute section I am trying to create a listview and custom adapter to display my data as follows:-
ListView yourListView = (ListView) rootView.findViewById(R.id.state_listView);
ListAdapter customAdapter = new ArrayAdapter<Person>(ByState.this, R.layout.bystate_itemview,personData);
yourListView .setAdapter(customAdapter);
}
}
public class ListAdapter extends ArrayAdapter<Person> {
public ListAdapter(Context context, int textViewResourceId) {
super(context, textViewResourceId);
}
public ListAdapter(Context context, int resource, ArrayList<Person> items) {
super(context, resource, items);
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi;
vi = LayoutInflater.from(getContext());
v = vi.inflate(R.layout.bystate_itemview, null);
}
Person p = getItem(position);
if (p != null) {
TextView tt1 = (TextView) v.findViewById(R.id.last_name);
TextView tt2 = (TextView) v.findViewById(R.id.first_name);
if (tt1 != null) {
tt1.setText(p.getLastname());
}
if (tt2 != null) {
tt2.setText(p.getFirstname());
}
}
return v;
}
}
}
I got the above code following some internet tutorial. The thing is I am getting an error in the line where I use the customadapter first to invoke the constructor of custom adapter. It says cannot resolve constructor. Can someone help me in understanding this. I know I have not defined the proper constructor for my case please let me know the changes. I am creating the listview inside a fragment and the fragment class name is ByState.
In second line replace
ListAdapter customAdapter = new ArrayAdapter<Person>(ByState.this, R.layout.bystate_itemview,personData);
by
ListAdapter customAdapter = new ListAdapter(ByState.this, R.layout.bystate_itemview, personData);
You create your own adapter class, but invoke standart ArrayAdapter
I apologize in advance if this is a duplicate. I am still new to android development and tried looking for a resolution however could not find one that works.
I am creating a to-do app and getting this error in my adapter.
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String assignment.Model.getAssignment()' on a null object reference
at assignment.Adapter.getView(Adapter.java:39)
and the line of code that it is referencing to is
assignment.setText(modelItems[position].getAssignment());
I believe that the position that I am setting it as is what is causing the error but I'm not sure how to fix it.
Here's part of the rest of my code for reference:
MainActivity.Java - onActivityResult
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
String assignmentSentBack = data.getStringExtra("editAssignment");
Integer monthSentBack = data.getIntExtra("month", 0);
Integer daySentBack = data.getIntExtra("day", 0);
modelItems = new Model[100];
ArrayList<Model> modelArrayList = new ArrayList<>(Arrays.asList(modelItems));
modelArrayList.add(new Model(assignmentSentBack, (monthSentBack + 1) + "/" + daySentBack, 0));
lv = (ListView) findViewById(R.id.listAssignment);
ListAdapter adapter = new Adapter(this, modelItems);
lv.setAdapter(adapter);
}
Second Activity - onSendActivity (Button)
public void onSendAssignment (View view) {
EditText editAssignmentET = (EditText)
findViewById(R.id.editAssignment);
String editAssignment = String.valueOf(editAssignmentET.getText());
DatePicker datePickerDP = (DatePicker)
findViewById (R.id.datePicker);
Integer month = Integer.valueOf(datePickerDP.getMonth());
Integer day = Integer.valueOf(datePickerDP.getDayOfMonth());
Intent goingBack = new Intent();
goingBack.putExtra("editAssignment", editAssignment);
goingBack.putExtra ("month", month);
goingBack.putExtra("day", day);
setResult(RESULT_OK, goingBack);
finish();
}
Adapter
public class Adapter extends ArrayAdapter {
Model[] modelItems = null;
Context context;
public Adapter(Context context, Model[] resource) {
super(context, R.layout.row, resource);
this.context = context;
this.modelItems = resource;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
convertView = inflater.inflate(R.layout.row, parent, false);
TextView assignment = (TextView) convertView.findViewById(R.id.assignment);
TextView dueDate = (TextView) convertView.findViewById(R.id.dueDate);
CheckBox cb = (CheckBox) convertView.findViewById(R.id.checkBox);
assignment.setText(modelItems[position].getAssignment());
dueDate.setText(modelItems[position].getDueDate());
if (modelItems[position].getValue() == 1)
cb.setChecked(true);
else
cb.setChecked(false);
return convertView;
}
}
Model
public class Model {
String assignment;
String dueDate;
int value;
Model (String assignment, String dueDate, int value){
this.assignment = assignment;
this.dueDate = dueDate;
this.value = value;
}
public String getAssignment(){
return this.assignment;
}
public String getDueDate(){
return this.dueDate;
}
public int getValue(){
return this.value;
}
}
Any help is appreciated. Thank you.
you should try to wrap it in an inner Holder class and define the parameters in that class
public class Adapter extends ArrayAdapter {
Model[] modelItems = null;
Context context;
public Adapter(Context context, Model[] resource) {
super(context, R.layout.row, resource);
this.context = context;
this.modelItems = resource;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = ((Activity) context).getLayoutInflater();
if (convertView == null) {
holder = new ViewHolder();
convertView = vi.inflate(R.layout.list_layout, null);
// Find the child views.
holder.assignment= (TextView) convertView.findViewById(R.id.txt_name);
holder.dueDate= (Button) convertView.findViewById(R.id.btn_invite);
holder.cb= (Button) convertView.findViewById(R.id.btn_track);
convertView.setTag(holder);
//....
}
// Reuse existing row view
else {
holder = (ViewHolder)convertView.getTag();
}
return convertView;
}
class ViewHolder {
TextView assignment;
TextView dueDate;
CheckBox cb;
}
}
change
public class Adapter extends ArrayAdapter {
to
public class Adapter extends ArrayAdapter<Model> {
You have created model array of size 100 here:
modelItems = new Model[100];
So, 100 models are being created but all 100 indexes have null value.
Then you have created ArrayList using that array:
ArrayList<Model> modelArrayList = new ArrayList<>(Arrays.asList(modelItems));
So again your modelArrayList has 100 null objects. Which BTW you are using no where.
You are passing modelItems into constructor of Adapter. So now since all you items are null, you are getting this exception.
Try to do something like this:
ArrayList<Model> modelArrayList = new ArrayList<>();
modelArrayList.add(new Model(assignmentSentBack, (monthSentBack + 1) + "/" + daySentBack, 0));
Similarly add more model objects like that.
Pass this modelArrayList in your adapter's constructor and use this (instead of array) to display the list.
lv = (ListView) findViewById(R.id.listAssignment);
ListAdapter adapter = new Adapter(this, modelArrayList)
And thus your adapter will be like this:
ArrayList<Model> modelArrayList;
Context context;
public Adapter(Context context, ArrayList<Model> resource) {
super(context, R.layout.row, resource);
this.context = context;
this.modelArrayList = resource;
}
I have a special class, a custom adapter for my ListView and I need to get some data from another Activity. But my implementation of the method GetIntent()GetExtras() isn't working. What is wrong?
Here is my custom adapter code:
public class CustomAdapter extends ArrayAdapter<String> {
int myColor,myWidth;
private final Context context;
private final String[] values;
public CustomAdapter(Context context, String[] values) {
super(context, R.layout.list_item, values);
this.context = context;
this.values = values;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// return super.getView(position, convertView, parent);
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.list_item, parent, false);
TextView textView = (TextView) rowView.findViewById(R.id.ColorTextButton);
ImageView imageView = (ImageView) rowView.findViewById(R.id.imageViewIcon);
TextView textView1 = (TextView) rowView.findViewById(R.id.HelpButton);
textView.setText(values[position]);
String s = values[position];
System.out.println(s);
if (s.equals("Monday")) {
imageView.setImageResource(R.drawable.arrow2);
textView.setBackgroundColor(Color.YELLOW);
} else if (s.equals("Wednesday")) {
imageView.setImageResource(R.drawable.arrow2);
textView1.setBackgroundColor(Color.GREEN);
} else if (s.equals("Friday")) {
imageView.setImageResource(R.drawable.arrow2);
} else {
imageView.setImageResource(R.drawable.arrow);
}
return rowView;
}
}
If you want the data to be accessable From a few activities you should think about use a singleton data Class. so in stead of trying to get pass the data from your adapter to a second activity both the adaper and the Activity use the same method to get the data class
public class DataProvider {
private static DataProvider instance;
public static DataProvider getInstance()
{
if(null == instance){instance = new DataProvider();}
return instnace;
}
public String[] getObjects(){
return this.myStringArray;
}
// add more methods in here to retrieve and count your data as you need
}
then in your Activity you can
// somewhere
myStingArrayInMyActivity = DataProvider.getInstance().getObjects()
also in you adapter
you can do
public class CustomAdapter extends ArrayAdapter<String> {
int myColor,myWidth;
private final Context context;
private final String[] values;
public CustomAdapter(Context context, String[] values) {
super(context, R.layout.list_item, values);
this.context = context;
this.values = values;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
// your code
textView.setText(DataProvider.getInstance.getObjects[position]);
String s = DataProvider.getInstance.getObjects[position];
/// your code
return rowView;
}
}
Sorry for my english. I use SlideMenu libruary and i want use new font for textview, it old version use:
((ListView) ((Activity) context).findViewById(R.id.sidemenulistobject)).setAdapter(
new ArrayAdapter<Object>(
context,
R.layout.sidemenu_item,
R.id.textSlide,
items
)
);
But this i cant get my textSlide and set new font. Now i add array adapter and set this in listView. This is my all code:
menu = new SlidingMenu(context);
menu.setMode(SlidingMenu.LEFT);
menu.setTouchModeAbove(SlidingMenu.TOUCHMODE_MARGIN);
menu.setShadowWidth(15);
menu.setFadeDegree(1.0f);
menu.setShadowWidthRes(R.dimen.shadow_width);
menu.setShadowDrawable(R.drawable.shadow);
menu.attachToActivity((Activity) context, SlidingMenu.SLIDING_WINDOW);
menu.setBehindWidth(400);
menu.setMenu(R.layout.sidemenu);
//add item in list view
ArrayList<String> itemsObj = new ArrayList<String>();
itemsObj.add("Новости");
itemsObj.add("События");
itemsObj.add("Наше меню");
itemsObj.add("Фотографии");
itemsObj.add("Видеозаписи");
itemsObj.add("Контакты");
itemsObj.add("Мой профиль");
//get sidemenulistobject
ListView lv = ((ListView) ((Activity) context).findViewById(R.id.sidemenulistobject));
//add adapter
SlideAdapter adapter = new SlideAdapter((Activity) context, R.layout.sidemenu_item, itemsObj);
lv.setAdapter(adapter);
This is my SlideAdapter
public class SlideAdapter extends ArrayAdapter<MenuCategoryObject>{
ArrayList<String> listItems;
int Resourse;
Context context;
LayoutInflater vi;
private ImageLoader imageLoader;
public SlideAdapter(Context context, int resource, ArrayList<String> listItems) {
super(context, resource);
this.listItems = listItems;
Resourse = resource;
this.context = context;
vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public View getView(final int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if(convertView == null) {
convertView = vi.inflate(Resourse, null);
holder = new ViewHolder();
Typeface face=Typeface.createFromAsset(context.getAssets(), "font/AvenirNext-Medium.ttf");
holder.textSlide = (TextView) convertView.findViewById(R.id.textSlide);
holder.textSlide.setTypeface(face);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.textSlide.setText(listItems.get(position));
return convertView;
}
static class ViewHolder {
public TextView textSlide;
}
}
But my item list view dont show. I dont know why. Please help
the problem is with your adapter. Since you are not providing the dataset to the super constructor, you have to override getCount and return its size. Add
public int getCount() {
return listItems.size();
}
to your adapter
why in every example i see that extends the class ArrayAdapter it overrides the constructor that accepts T[] objects and references its own private variable to that and uses the referenced variable in the override of getView?
how can this be dynamic adding of objects?
will values be updated when a new item is added to the ArrayAdapter using add method?
can i instead of implementing my own adapter just use addheaderview in listview?
public class MySimpleArrayAdapter extends ArrayAdapter<String> {
private final Context context;
private final String[] values;
public MySimpleArrayAdapter(Context context, String[] values) {
super(context, R.layout.rowlayout, values);
this.context = context;
this.values = values;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View rowView = inflater.inflate(R.layout.rowlayout, parent, false);
TextView textView = (TextView) rowView.findViewById(R.id.label);
ImageView imageView = (ImageView) rowView.findViewById(R.id.icon);
textView.setText(values[position]);
// change the icon for Windows and iPhone
String s = values[position];
if (s.startsWith("iPhone")) {
imageView.setImageResource(R.drawable.no);
} else {
imageView.setImageResource(R.drawable.ok);
}
return rowView;
}
}