Develop Reference

How to check if a view is visible in future?

I have a view. The view might become visible at some time in the future. When this view is visible I want to call a method. How to do this?
val editText = findViewById<EditText>(R.id.editText)
// editText might become invisible in some time in future
// and in some in future it might visible
if(editText.isVisible(){
// code to be executed
}
Code for View.isVisible() :
fun View.isVisible() = this.visibility == View.VISIBLE // check if view is visible
Is there anything like View.setOnClickListener which could be applied and triggered when the view is visible-
editText.setOnClickListener { view ->
}

click listener is callback when the view is being clicked. it has no concern with its visibility. There is no method like isVisible(). to check Visibility
if(yourView.getVisiblity()==View.VISIBLE){ //your task}
for kotlin:
if(youView.visibility==View.VISIBLE){//your task}

I might initialize a variable int status of visibility and set it to 0 with the view invisible.
Now I would create a function instead directly setting the visibility of the view.
For example a function named onVisibilityChanged();
In that function add the set visibility code followed by setting the int to 0 or 1 as per the visibility an if-else block.
If you just set the view to visible, set the int to 1.
The reason for adding if-else block is to configure your actions based on the visibility status.
So that gives you the freedom to do whatever you want bases on the visibility.
Make sure you add this code in such a way that it is executed anytime you want.
Use the performClick() function to click any button or any other view.
I hope you understand. Or comment any query. I would have posted the code for the same but it looks like you are using Kotlin. So I'll try to post it in Kotlin if possible.
The main intention of doing such a thing is when the value of int changes, the app knows what to do and also knows that visibility has changed.
Just call the function wherever you want. It will be easy.
So this is what I am trying to do:
int visibilityStatus;
textview = findViewById(R.id.textview);
getInitialVisibility();
funcOnVisibilityChange();
}
private void getCurrentVisibility() {
if (textview.getVisibility() == View.VISIBLE) {
visibilityStatus = 1;
} else {
visibilityStatus = 0;
}
}
private void funcOnVisibilityChange() {
//Now change the visibility in thia function
textview.setVisibility(View.VISIBLE);
int currentVisibilityStatus;
if (textview.getVisibility() == View.VISIBLE) {
currentVisibilityStatus = 1;
} else {
currentVisibilityStatus = 0;
}
if (visibilityStatus != currentVisibilityStatus) {
//Visibility status has changed. Do your task
else {
//visibility status not changed
}
}
}
So all that we are doing is getting visibility of the view when the app is started and when you somehow change its visibility. Here in the example, I've directly changed the visibility. So wherever you know that visibility is going to change just put the funcOnVisibilityChange() and it will do your job... hope it helps. Let me know if you need more clarification.

collapse all recycler view sections except one.. set image resource

I am trying to collapse all sections in recyclerview except one ( currently selected)..
I can collapse all items successfully.. but I want to reverse the arrow direction in headerholder.. I Using the library as https://github.com/luizgrp/SectionedRecyclerViewAdapter..
while reversing the arrow it is giving null pointer exception for headerholders out of window ( not visible in present screen)..
{
for (int i = 0; i < deviceInfoList.size(); i++) {
ExpandableDeviceSection section = (ExpandableDeviceSection) sectionAdapter.getSection(deviceInfoList.get(i).getdName());
if (section.expanded && !section.dName.equals(dName)) {
section.expanded = false;
HeaderViewHolder headerViewHolder1=(HeaderViewHolder)recyclerView.findViewHolderForAdapterPosition(sectionAdapter.getHeaderPositionInAdapter(section.dName));
//getting null for sectionHeader which is not available.
if(headerViewHolder1!=null)
headerViewHolder1.imgArrow.setImageResource(section.expanded ? R.drawable.ic_expand_less : R.drawable.ic_expand_more);
}
}
// sectionAdapter.notifyDataSetChanged();
}
here is my all collapse code in onclick listener.. I hope this clarifies.. let me know if anything else required..

Problem solved.. forgot to set image view (imagearrow) in onbindheaderview holder..
No need to set it in for loop now .

Removing view when clicked, how to solve?

I noticed I was doing this in my code:
ResultButton = new Button( theActivity );
ButtonUtils.setButtonValues( ... );
((ViewGroup) (theActivity).findViewById( android.R.id.content )).addView( ResultButton );
ResultButton.setOnClickListener( new OnClickListener()
{
#Override
public void onClick(View arg0) {
doStuff();
((ViewGroup) (getActivity()).findViewById( android.R.id.content )).removeView( ResultButton );
}
});
That seems clearly wrong, to remove itself inside its OnClickListener. But what is the right way to deal with these things. Since there is no main method in an Android program I cannot just set a flag and then have it deal with it later.
You never really remove things? You just set them to invisible?

Inside your onClick implementation, the argument that you didn't rename corresponds to the view that triggered the event, you can call the parent of said view and ask it to remove the said child view.
ViewGroup parentView = (ViewGroup) view.getParent();
parentView.removeView(view);
To do this, rename arg0 to view, and you should be fine
Another option, as you mention is to just toggle its visibility, calling the setVisibility method, to either View.GONE or View.INVISIBLE depending on wether you want to to keep taking the screen space it was taking when visible or be completely gone, but since you asked to remove the view, the first option should suffice.

How to disable all buttons in a Layout?

The way app works is the following: App prompts 30 buttons to user and user may guess the right ones by tapping. When user taps some button all the buttons (say a view containing these buttons) should be locked while corresponding (right or wrong guess) animation is playing. Tapped button by itself should be disabled till the next round. After animation is finished all not tapped previously buttons (say a view containing these buttons) should be available again.
So I have a Layout which includes another layout with these 30 buttons:
...
<RelativeLayout
android:id="#+id/alphabetContainer"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<include layout="#layout/alphabet" />
</RelativeLayout>
...
Now I need to lock the buttons from being clicked and then unlock. So I tried:
...
private RelativeLayout alphabetPanel;
...
public void onCreate(){
...
alphabetPanel = (RelativeLayout) findViewById(R.id.alphabetContainer);
...
}
...
private void lockButtons(){
alphabetPanel.setEnabled(false);
}
but this doesn't lock buttons. I also tried:
alphabetPanel.setFocusable(false);
alphabetPanel.setClickable(false);
Doesn't help either. Seems like it all relies only to a layout by itself but not the views it contains.
Also I tried to add a fake layout to place it over layout with buttons by bringing it to the front. This is a workaround and its tricky cuz both layouts must be placed inside a RelativeLayout only:
...
blockingLayout = new RelativeLayout(this);
blockingLayout.setLayoutParams(alphabetPanel.getLayoutParams());
...
but this works very strange: somehow both layouts in this case appears and disappears every second or so or doesn't appear at all - I cant understand that at all cuz there is no setVisibility() method used in code!
The only one way left is to iterate every view (button) to make it disabled and than back.
Is there any other way?
UPDATE
Finally I had to add a "wall"-layout into the xml. Now by making it clickable and focusable it becomes a solution.

Try setting for each Button's xml definition
android:duplicateParentState="true"
I'm not sure, but I think it should make them not only to seem disabled, but also to act accordingly.

Hmm it surprises me that disabling the parent-layout doesn't work.. as far as i know it should.
Try fetching your included layout instead, and disable that.
Anyway, if all else fails you can always loop through the buttons themselves.
for(int i=0;i<relativeLayout.getChildCount();i++){
View child=relativeLayout.getChildAt(i);
//your processing....
child.setEnabled(false);
}

I used extension to lock and unlock the view
//lock
fun View.lock() {
isEnabled = false
isClickable = false}
//unlock
fun View.unlock() {
isEnabled = true
isClickable = true}
if you want to lock all children of the view group
//lock children of the view group
fun ViewGroup.lockAllChildren() {
views().forEach { it.lock() }}
//unlock children of the view group
fun ViewGroup.unlockAllChildren() {
views().forEach { it.unlock() }}

firstly define your button
Button bit = (Button)findViewById(R.id.but);
bit.setEnabled(false);
and set enabled false;

Java:-
public void disableButtons(Layout layout) {
// Get all touchable views
ArrayList<View> layoutButtons = layout.getTouchables();
// loop through them, if they are instances of Button, disable them.
for(View v : layoutButtons){
if( v instanceof Button ) {
((Button)v).setEnabled(false);
}
}
}
Kotlin:-
fun disableButtons(layout: Layout) {
// Get all touchable views
val layoutButtons: ArrayList<View> = layout.getTouchables()
// loop through them, if they are instances of Button, disable them.
for (v in layoutButtons) {
if (v is Button) {
(v as Button).setEnabled(false)
}
}
}
Retrieve all touchables views into an ArrayList, then loop through them and check if it is an instance of the Button or TextView or which ever you want, then disable it!

In case data binding is needed
import android.view.ViewGroup
import android.widget.Button
import androidx.core.view.children
import androidx.databinding.BindingAdapter
#BindingAdapter("disableButtons")
fun ViewGroup.setDisableButtons(disableButtons: Boolean) {
children.forEach {
(it as? Button)?.isEnabled = !disableButtons
}
}
Usage:
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:padding="#dimen/guideline"
app:disableButtons="#{vm.busy}">
....
</androidx.constraintlayout.widget.ConstraintLayout>

Might work in constraint layout . Use group widget and add all the button ids.
In the java code set enabled false for the group.

For disable all buttons in any nested layouts.
void DisableAllButtons( ViewGroup viewGroup ){
for( int i = 0; i < viewGroup.getChildCount(); i++ ){
if( viewGroup.getChildAt(i) instanceof ViewGroup ){
DisableAllButtons( (ViewGroup) viewGroup.getChildAt(i) );
}else if( viewGroup.getChildAt(i) instanceof Button ){
viewGroup.getChildAt(i).setEnabled( false );
}
}
}

write these two lines on your button declartion in XML
android:setEnabled="false"
android:clickable="false"

Getting list of all Windows in Android

Is it possible to get a list of all Windows in my Android app?
If not, is it possible to get notifications on creation of a new View or a Window?
Cheers :)
For example: I would like to know if there's a visible keyboard view on the screen, or if there's an alert dialog on screen. Is that possible? Can I get the View or Window instance holding it?

Yes this is possible in a number of different ways. All views being displayed on the screen are added to a ViewGroup, which are usually layouts such as R.layout.main, LinearLayout, RelativeLayout, etc.
You can access the views at runtime, after the layouts have been built, using a handler such as onWindowFocusChanged:
#Override
public void onWindowFocusChanged(boolean hasFocus) {
int count = myLayout.getChildCount();
for(int i = 0; i < count; i++)
{
View v = myLayout.getChildAt(i);
...
}
}
You can simply set up a thread inside onWindowFocusChanged that would notify you if a keyboard is created by constantly checking the number of children views of the current layout.

For the keyboard issue, you can use your own keyboard view instance with KeyboardView in your layout: http://developer.android.com/reference/android/inputmethodservice/KeyboardView.html
Use the same principle for the other views you want to handle: manage them yourself in your layout. I don't know if you can in the software you plan to do but this is a way which can work.

You can only get views which are managed by your application.
This includes all views except the status and navigation bars(for higher than HoneyComb). If you choose to have your own InputMethod, that view can be yours as well but you'll need to register the proper keyboard views. See this question for more on that.
Otherwise, if you want to get all the views in your window:
ViewGroup decor = (ViewGroup)activity.getWindow().getDecorView();
int count = decor.getChildCount();
for(int i = 0; i < count; i++) {
View view = decor.getChildAt(i); //voila
}

hey use this code this will help you to find if any dialog is created in your activity
class MyActivity extends Activity {
#Override
public void onAttachedToWindow() {
super.onAttachedToWindow();
Log.d("TAG", "New Window ATTACHED");
}
}
onAttachedToWindow will be called every time user creates new dialog or something