I have a xml layout with an element i use multiple times... so i decided to use <include> in the xml to avoid excess code.
My problem is that i want to make a class that is connected to this included xml component and reference to it, rather than writing the same code multiple times.
I tried to read up on a custom view component and created a class ParcelPopbarView:
public ParcelTopBarView extends View {
/...
public ParcelTopBarView(Context context, ParcelListItem parcelListItem) {
super(context);
this.parcelListItem = parcelListItem;
this.context = context;
titleTextView = findViewById(R.id.title_textview);
subtitleTextView = findViewById(R.id.subtitle_textview);
deliveryInfoTextView = findViewById(R.id.delivery_info_textview);
thumbnailLogo = findViewById(R.id.thumbnail_logo);
}
public void setTopbar(){
titleTextView.setText("hello!");
}
But i felt like custom views mostly is about drawing on a canvas, i am not doing that... so i dont know if using view is right either.
Either way, the titleTextView is null cause it cannot find the refrence to the xml file, and i have no idea how to reference to it hahah.
Does anyone have a smart solution to how i can do this the right way?
You need to inflate the layout for all the constructors of your custom view to be able to access them later.
public class ParcelTopBarView extends View {
public ParcelTopBarView(Context context) {
super(context);
init();
}
public ParcelTopBarView(Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
init();
}
public ParcelTopBarView(Context context, #Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
public ParcelTopBarView(Context context, #Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
init();
}
private void init() {
View view = inflate(getContext(), R.layout.parcel_top_bar, this);
titleTextView = findViewById(R.id.title_textview);
subtitleTextView = findViewById(R.id.subtitle_textview);
deliveryInfoTextView = findViewById(R.id.delivery_info_textview);
thumbnailLogo = findViewById(R.id.thumbnail_logo);
}
Related
Where can i add the listeners so the are always added, no matters if the custom view is created from xml or if is inflated.
I try on onFinishInflate but is only called if the view is created from xml layout. There is no OnViewCreated or something like that where i can be sure that all inside views are created and an listener can be attached.
Update: Typical compound view
public class CustomView extends RelativeLayout{
//called directy
public CustomView(Context context) {
super(context);
initializeViews(context);
}
private void initializeViews(final Context context) {
LayoutInflater inflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
inflater.inflate(R.layout.myview_layout, this);
}
//called when used inside xml layout
public ChatView(Context context, AttributeSet attrs) {
super(context, attrs);
initializeViews(context);
}
//idem
public ChatView(Context context,
AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
initializeViews(context);
}
I have a custom RelativeLayout and I inflate an xml res file in it.
This works fine if I use the custom layout in an xml file and set it as contentview, but if I try to add it in the code with new LocationItem(this) and addChild() the findViewById method always returns null in the constructor of the custom RelativeLayout.
Here is the code:
public class LocationItem extends RelativeLayout {
private String parcelType;
private int countIntoBox, countFromBox;
private RelativeLayout deliveryContainer, pickupContainer;
private TextView countPickup, countDelivery;
public LocationItem(Context context) {
this(context, null);
}
public LocationItem(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public LocationItem(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
inflate(getContext(), R.layout.list_item_location, this);
deliveryContainer = (RelativeLayout) findViewById(R.id.rl_location_delivery_container);
pickupContainer = (RelativeLayout) findViewById(R.id.rl_location_pickup_container);
countPickup = (TextView) findViewById(R.id.tv_location_pickup_count);
countDelivery = (TextView) findViewById(R.id.tv_location_delivery_count);
countPickup.setOnClickListener(getShowNumberPickerListener());
countDelivery.setOnClickListener(getShowNumberPickerListener());
}
private OnClickListener getShowNumberPickerListener() {
return new OnClickListener() {
#Override
public void onClick(View view) {
showNumberPickerDialog(view);
}
};
} ...
}
Add custom view in activity
mRootLayoutLocations.addView(new LocationItem(this));
The view is inflated correctly, because I can see it, but when I try to access a view inside the custom view the app crashes with a NullPointerException.
Ok i inflated the view into a View(holder)
View v = inflate(getContext(), R.layout.list_item_location, this);
and then access the views via v.findViewById. Now it's working.
Code:
View v = inflate(getContext(), R.layout.list_item_location, this);
deliveryContainer = (RelativeLayout) v.findViewById(R.id.rl_location_delivery_container);
pickupContainer = (RelativeLayout) v.findViewById(R.id.rl_location_pickup_container);
countPickup = (TextView) v.findViewById(R.id.tv_location_pickup_count);
countDelivery = (TextView) v.findViewById(R.id.tv_location_delivery_count);
countPickup.setOnClickListener(getShowNumberPickerListener());
countDelivery.setOnClickListener(getShowNumberPickerListener());
You need to be using appropriate constructors, not overloading them.
public class LocationItem extends RelativeLayout {
private String parcelType;
private int countIntoBox, countFromBox;
private RelativeLayout deliveryContainer, pickupContainer;
private TextView countPickup, countDelivery;
public LocationItem(Context context) {
super(context);
init(context, null, 0);
}
public LocationItem(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs, 0);
}
public LocationItem(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs, defStyle);
}
private void init(Context context, AttributeSet attrs, int defStyle) {
inflate(getContext(), R.layout.list_item_location, this);
deliveryContainer = (RelativeLayout) findViewById(R.id.rl_location_delivery_container);
pickupContainer = (RelativeLayout) findViewById(R.id.rl_location_pickup_container);
countPickup = (TextView) findViewById(R.id.tv_location_pickup_count);
countDelivery = (TextView) findViewById(R.id.tv_location_delivery_count);
countPickup.setOnClickListener(getShowNumberPickerListener());
countDelivery.setOnClickListener(getShowNumberPickerListener());
}
private OnClickListener getShowNumberPickerListener() {
return new OnClickListener() {
#Override
public void onClick(View view) {
showNumberPickerDialog(view);
}
};
}
...
}
I fear you must inflate the view instead of finding it from nowhere. The method
findindViewById(int Id)
must be called within the Actvity's onCreate or with a view within which the child view/widget you are trying to find is resides in.
If all of the child views resides in a single xml file(within single parent root)
View rootView=(View) LayoutInflater.from(context).inflate(R.layout.list_item_location);
pickupContainer = (RelativeLayout) rootview.findViewById(R.id.rl_location_pickup_container);
you can try this. init views in the method onFinishInflate().This method will be called called as the last phase of inflation, after all child views have been added.So you can avoid NPE.
this should work
public LocationItem(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this = inflate(getContext(), R.layout.list_item_location,null);
...
I am building a custom View that requires as one of its Attributes a Class<> object to an entity. While I made it work programmatically by adding a Setter for it, I was wondering if there is any good way to allow adding it to the XML for the layout as well?
There does not appear to be a format option for a styleable with type "class". I could use a String, but then I'd have to gamble that the value is actually a valid Class and I'd lose type hinting, so it'd not be ideal.
Is there any good way to make this work, or should I just stick with setting it programmatically?
Method 1 (With warnings):
Generic CustomView:
public class CustomView<T> extends View {
private List<T> typedList = new ArrayList<T>();
public CustomView(Context context) {
this(context, null);
}
public CustomView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public void addTypedValue(T object){
typedList.add(object);
}
public T getTypedValue(int position){
return typedList.get(position);
}
}
Activity:
//unsafe cast!
CustomView<String> customViewGeneric = (CustomView<String>) findViewById(R.id.customView);
customViewGeneric.addTypedValue("Test");
String test = customViewGeneric.getTypedValue(0);
XML:
<org.neotech.test.CustomView
android:id="#+id/customView"
android:layout_width="wrap_content"
android:layout_height="match_parent" />
Method 2 (No warnings, safe!):
This method uses a generic CustomView. And for each type that will be used in xml you will need to create a specific class.
I have added an example implementation:
Generic CustomView: (Do not inflate this one in xml):
public class CustomView<T> extends View {
private List<T> typedList = new ArrayList<T>();
public CustomView(Context context) {
this(context, null);
}
public CustomView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public void addTypedValue(T object){
typedList.add(object);
}
public T getTypedValue(int position){
return typedList.get(position);
}
}
XML inflatable view for the String type:
public class CustomViewString extends CustomView<String> {
//ADD Constructors!
}
XML inflatable view for the Integer type:
public class CustomViewInteger extends CustomView<Integer> {
//ADD Constructors!
}
Activity:
CustomViewString customViewString = (CustomViewString) findViewById(R.id.customViewString);
CustomView<String> customViewGeneric = customViewString;
XML:
<org.neotech.test.CustomViewString
android:id="#+id/customViewString"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<org.neotech.test.CustomViewInteger
android:id="#+id/customViewInteger"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
I am creating my own layout based on RelativeLayout as a class in code
I have basics of the layout defined in XML R.layout.menu_layout (style, drawable for background, margin, height)
If I would not need a class then I would call inflater to do this:
RelativeLayout menuLayout = (RelativeLayout)inflater.inflate(R.layout.menu_layout, root);
But I would like to be calling my own class instead
MenuLayout menuLayout = new MenuLayout(myparams);
Since I need to create a class I need to somehow inherit the R.layout.menu_layout in constructor, how can I do that? I guess there is no this.setLayout(res); or this.setResource(res); in View. Maybe I can use the other two parameters in View constructor but I did not find any tutorial how to do that either.
public class MenuLayout extends RelativeLayout {
public MenuLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView(context);
}
public MenuLayout(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context);
}
public MenuLayout(Context context) {
super(context);
initView(context);
}
private void initView(Context context) {
View view = LayoutInflater.from(context).inflate(R.layout.menu_layout, null);
addView(view);
}
}
now you can use
MenuLayout menuLayout = new MenuLayout(myparams);
you can change constructors for params i think
I'm trying something like this
public class CustomViewSubclass extends HorizontalScrollView{
private LinearLayout layout;
public CustomViewSubclass(Context context) {
this(context,null,0);
}
public CustomViewSubclass(Context context, AttributeSet attrs) {
this(context,attr,0);
}
public CustomViewSubclass(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
layout = new LinearLayout(context);
}
// This is called from the `Activity`
public void startAsyncTask() { // code }
// This method is called in the `onPostExecute()` of an `AsyncTask` subclass
public void doSomething(Context context) {
ImageView image = ImageView(context);
layout.addView(image); // NullPointerException here, layout seems to be null
}
but it seems that layout on doSomething() is null. How is that even possible? I'm initializing it on the constructor... and I never re-initialize it again;
I'm adding my custom view via XML
<com.mypackage.CustomViewSubclass
android:layout_width="wrap_content"
android:layout_width="match_parent" />
Ok I fixed it, it was an stupid mistake made by me:
I used super() on the 3 methods, instead of using this().
public CustomViewSubclass(Context context) {
super(context,null,0);
}
public CustomViewSubclass(Context context, AttributeSet attrs) {
super(context,attr,0);
}
public CustomViewSubclass(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
layout = new LinearLayout(context);
}
Solution:
public CustomViewSubclass(Context context) {
this(context,null,0);
}
public CustomViewSubclass(Context context, AttributeSet attrs) {
this(context,attr,0);
}
public CustomViewSubclass(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
layout = new LinearLayout(context);
}