I added a header to a list view
in the past When scrolling up or down throw exception
That was solved with a custom view list:
public MyFixedListView(Context context) {
super(context);
}
public MyFixedListView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public MyFixedListView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public MyFixedListView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
#Override
protected void dispatchDraw(Canvas canvas) {
try {
super.dispatchDraw(canvas);
} catch (IndexOutOfBoundsException e) {
e.printStackTrace();
}
}
But now the Android 6.0.1 (marshmallow) , once again, the show was former error:
in my stack trase :
java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0 : at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
add header :
private void Create_Header_Sjd_init() {
LayoutInflater inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
convertViewHeader = inflater.inflate(R.layout.row_idea_list , null);
convertViewHeader.setBackgroundColor(getResources().getColor(R.color.gray_light_light));
listView.addHeaderView(convertViewHeader, null, false);
}
resovle this error by sub code :
listView.setFooterDividersEnabled(false);
listView.addFooterView(new View(this), null, false);
IndexOutOfBoundsException,maybe you can check you code about list of data or item view
If your list size id Zero then for adding header to list view you have set this..
listView.setAdapter(null);
Related
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);
}
I am facing one exception in my Custom Linear layout. Please see the sample code below.
public class ParentView extends LinearLayout {
private Menu mMenu;
public DontPressWithParentView(Context context, AttributeSet attrs, Menu menu) {
super(context, attrs);
mMenu = menu;
}
}
When I am using this layout in xml like below
com.android.ParentView
android:id="#+id/call_icon"
android:layout_width="91dip"
android:layout_height="83dip"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:layout_marginRight="22dip"
android:gravity="center" >
</com.android.hParentView>
It is giving me xml inflate exception. Please help me.
You have to implement the following constructors in your Viewcode:
public ParentView(Context context) {
super(context);
}
public ParentView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public ParentView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#TargetApi (Build.VERSION_CODES.LOLLIPOP)
public ParentView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
Furthermore please check if your package declaration in your xml is correct:
com.android.ParentView
It sounds a bit weird to me.
I am extending a frame layout
and when in the constructor (after it loaded the view from xml) i call getChildCount()
I get 0. How to fix this ?
public class DisabledFrameLayout extends FrameLayout {
public DisabledFrameLayout(Context context) {
super(context);
init(context, null,0);
}
public DisabledFrameLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context,attrs,defStyle);
}
public DisabledFrameLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init(context,attrs,0);
}
private void init(Context context, AttributeSet attrs, int defStyle) {
TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.DisabledFrameLayout, 0, 0);
if(a.hasValue(R.styleable.DisabledFrameLayout_disable_descendants)) {
boolean disable = a.getBoolean(R.styleable.DisabledFrameLayout_disable_descendants, false);
if(disable) {
disableDescendants(this);
}
}
a.recycle();
}
private void disableDescendants(ViewGroup v) {
for (int i=0; i<v.getChildCount();i++) {
if(v.getChildAt(i) instanceof ViewGroup) {
disableDescendants((ViewGroup)v.getChildAt(i));
}
v.setEnabled(false);
v.setFocusable(false);
v.setFocusableInTouchMode(false);
}
}
}
xml
<com.lenabru.DisabledFrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:disable_descendants="true"
>
<include
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
layout="#layout/fragment_p" />
</com.lenabru.DisabledFrameLayout>
In state of constructing your FrameLayout, children are still not fully attached to the view. So, calling getChildCount() will return you 0.
If you want to iterate over child views and update them, do it inside onLayout() or onMeasure().
Refs:
http://blog.denevell.org/android-custom-views-onlayout-onmeasure.html
ViewGroup - check this example code.
Using the following code:
public class CustomView extends RelativeLayout {
public CustomView(Context context) {
this(context, null, 0);
}
public CustomView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
private void initView() {
inflate(getContext(), R.layout.custom_view, this);
}
}
The layout is simple:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/custom_view_id"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#f00"/>
The hierarchyviewer shows the following:
The CustomView hierarchy is useless and I would like to remove it.
Is there a way to create a custom view extending a ViewGroup without adding that additional View?
If your CustomView is already a RelativeLayout in you XML layout you can just delete the RelativeLayout with "#+id/custom_view_id" and use as father the tag
That will merge the children with the CustomView without using an extra RelativeLayout.
The CustomView will setBackgroundColor
public class CustomView extends RelativeLayout {
public CustomView(Context context) {
this(context, null, 0);
}
public CustomView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initView();
}
private void initView() {
setBackgroundColor(Color.parseColor("#f00"));
inflate(getContext(), R.layout.custom_view, this);
}}
and the layout xml file will be:
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<!-- children here -->
</merge>
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);
}