Develop Reference

How to make a set of views invisible in android

I'm trying to make a set of views (that include several textviews and buttons - all in different parent layouts, but in the same activity) invisible if a particular condition is evaluated to false.
The conventional way to do that would be:
findViewById(R.id.myview).setVisibility(View.INVISIBLE);
My question is, will I have to do this for all the views one by one that I want to be invisible, And then toggle them back when I want them visible?
Or, is there a way to avoid the code-repetition?

If the Views are in different parents , you can't do it directly, but you can implement a method to change the visibility of a bunch of Views if you want to keep your code clean:
List<View> relatedViews = new ArrayList<>();
// ...
relatedViews.add(view1);
relatedViews.add(view2);
relatedViews.add(view3);
// ...
changeVisibility(relatedViews, View.INVISIBLE);
// ...
private void changeVisibility(List<View> views, int visibility) {
for (View view : views) {
view.setVisibility(visibility);
}
}
As a side note, you may want to change the visibility to View.GONE instead of View.INVISIBLE so it doesn't take any space in the layout.

you can use something like this. It's not the most elegant solution but works.
The idea is give to each view that you want to hide a same content description, because in the same layout you can not use same id for multiple view. With the same content description you can find all views in your layout and hide them.
That's an example considering the first layout as Linear. You can change obviously ;)
public class TestActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
LinearLayout rootLayout = (LinearLayout)findViewById(R.id.rootLayout);
int childcount = rootLayout.getChildCount();
for (int i=0; i < childcount; i++){
View v = rootLayout.getChildAt(i);
if(v.getContentDescription() != null && v.getContentDescription().equals("invisibleView")){
v.setVisibility(View.INVISIBLE);
//I suggest you to use GONE instead of INVISIBLE to remove the space of the view
}
}
}
}
in your xml give to the object that you want to hide this property
android:contentDescription="invisibleView"

Use varargs method for show or hide multiple views.
for example if you have views like view1, view2.....etc
then just call setVisibility(View.VISIBLE,view1,view2)
public static void setVisibility(int visibility, View... views){
for (View view : views){
view.setVisibility(visibility);
}
}

Android ExpandableListView using animation

I'm using
<ExpandableListView
android:id="#+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</ExpandableListView>
i want add animation slide for child when onclick parent . So How can i do ?

Final Update
It's been quite a while since I wrote this answer. Since then a lot has changed. The biggest change is with the introduction of RecyclerView that makes animating a list or grid easy. I highly recommend switching over to RecyclerViews if you can. For those who can't I will see what I can do regarding fixing the bugs for my library.
Original answer
I actually do not like the popular implementation of an animated ExpandableListView that simply uses a ListView with an expand animation because in my use case, each of my groups had a lot of children, therefore it was not feasible to use a normal ListView as the child views will not be recycled and the memory usage will be huge with poor performance. Instead, I went with a much more difficult but more scalable and flexible approach.
I extended the ExpandableListView class and overrode the onCollapse and onExpand functions, I also created a subclass of a BaseExpandableListAdapter called AnimatedExpandableListAdapter. Inside the adapter, I overrode the getChildView function and made the function final so that the function cannot be overrode again. Instead I provided another function called getRealChildView for subclasses to override to provide a real child view. I then added an animation flag to the class and made getChildView return a dummy view if the animation flag was set and the real view if the flag was not set. Now with the stage set I do the following for onExpand:
Set the animation flag in the adapter and tell the adapter which group is expanding.
Call notifyDataSetChanged() (forces the adapter to call getChildView() for all views on screen).
The adapter (in animation mode) will then create a dummy view for the expanding group that has initial height 0. The adapter will then get the real child views and pass these views to the dummy view.
The dummy view will then start to draw the real child views within it's own onDraw() function.
The adapter will kick off an animation loop that will expand the dummy view until it is of the right size. It will also set an animation listener so that it can clear the animation flag once the animation completes and will call notifyDataSetChanged() as well.
Finally with all of this done, I was able to not only get the desired animation effect but also the desired performance as this method will work with group with over 100 children.
For the collapsing animation, a little more work needs to be done to get this all setup and running. In particular, when you override onCollapse, you do not want to call the parent's function as it will collapse the group immediately leaving you no chance to play an animation. Instead you want to call super.onCollapse at the end of the collapse animation.
UPDATE:
I spent some time this weekend to rewrite my implementation of this AnimatedExpandableListView and I'm releasing the source with an example usage here:
https://github.com/idunnololz/AnimatedExpandableListView/

animateLayoutChanges adds auto-animation
<ExpandableListView
android:animateLayoutChanges="true"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>

#idunnololz solution works great. however i would like to add some code to collapse previously expanded group.
private int previousGroup=-1;
listView.setOnGroupClickListener(new OnGroupClickListener() {
#Override
public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
// We call collapseGroupWithAnimation(int) and
// expandGroupWithAnimation(int) to animate group
// expansion/collapse.
if (listView.isGroupExpanded(groupPosition)) {
listView.collapseGroupWithAnimation(groupPosition);
previousGroup=-1;
} else {
listView.expandGroupWithAnimation(groupPosition);
if(previousGroup!=-1){
listView.collapseGroupWithAnimation(previousGroup);
}
previousGroup=groupPosition;
}
return true;
}
});

#idunnololz solution is working great, but I experienced weird behavior with my custom layout for group. The expand operation was not executed properly, the collapse however worked perfect. I imported his test project and it worked just fine, so I realized the problem is with my custom layout. However when I was not able to locate the problem after some investigation, I decided to uncomment these lines of code in his AnimatedExpandListView:
if (lastGroup && Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
return expandGroup(groupPos, true);
}
which caused the problem (my app is aimed for Android 4.0+).

Found this snnipet not remebering where here in Stack Overflow. Have two basic static methods: expand(View v) and collapse(View v).
You only have to pass the view you want to hide show.
Note: I Don't recomend pass a view having wrap_content as height. May not work fine.
public class expand {
public static void expand(View view) {
view.setVisibility(View.VISIBLE);
final int widthSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
final int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
view.measure(widthSpec, heightSpec);
ValueAnimator mAnimator = slideAnimator(view, 0, view.getMeasuredHeight());
mAnimator.start();
}
public static void collapse(final View view) {
int finalHeight = view.getHeight();
ValueAnimator mAnimator = slideAnimator(view, finalHeight, 0);
mAnimator.addListener(new Animator.AnimatorListener() {
#Override
public void onAnimationEnd(Animator animator) {
view.setVisibility(View.GONE);
}
#Override
public void onAnimationStart(Animator animation) {
}
#Override
public void onAnimationCancel(Animator animation) {
}
#Override
public void onAnimationRepeat(Animator animation) {
}
});
mAnimator.start();
}
private static ValueAnimator slideAnimator(final View v, int start, int end) {
ValueAnimator animator = ValueAnimator.ofInt(start, end);
animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
#Override
public void onAnimationUpdate(ValueAnimator valueAnimator) {
int value = (Integer) valueAnimator.getAnimatedValue();
ViewGroup.LayoutParams layoutParams = v.getLayoutParams();
layoutParams.height = value;
v.setLayoutParams(layoutParams);
}
});
return animator;
}
}

Can I partially hide a layout?

As I've a master in MS Paint, I will just upload a picture selfdescripting what I'm trying to achieve.
I've searched, but I'm not really sure what do I've to search. I've found something called Animations. I managed to rotate, fade, etc an element from a View (with this great tutorial http://www.vogella.com/articles/AndroidAnimation/article.html)
But this is a bit limited for what I'm trying to achieve, and now, I'm stuck, because I don't know how is this really called in android development. Tried words like "scrollup layouts" but I didn't get any better results.
Can you give me some tips?
Thank you.
You can see a live example, with this app: https://play.google.com/store/apps/details?id=alexcrusher.just6weeks
Sincerely,
Sergi

Use something like this as your layout (Use Linear, Relative or other layout if you wish):
<LinearLayout
android:id="#+id/lty_parent">
<LinearLayout
android:id="#+id/lyt_first" />
<LinearLayout
android:id="#+id/lyt_second"/>
</LinearLayout>
And then in an onClick method on whatever you want to use to control it, set the Visibility between Visible and Gone.
public void buttonClickListener(){
((Button) findViewById(R.id.your_button))
.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
if (lyt_second.getVisibility() == View.GONE) {
lyt_second.setVisibility(View.VISIBILE);
}
else {
lyt_second.setVisibility(View.GONE);
}
});
Which is fine if you just want a simple appear/disappear with nothing fancy. Things get a little bit more complicated if you want to animate it, as you need to play around with negative margins in order to make it appear to grow and shrink, like so:
We use the same onClick method that we did before, but this time when we click it starts up a custom SlideAnimation for the hidden/visible view.
#Override
public void onClick(View v) {
SlideAnimation slideAnim = new SlideAnimation(lyt_second, time);
lyt_second.startAnimation(slideAnim);
}
The implementation of the SlideAnimation is based on a general Animation class, which we extend and then Override the transformation.
public SlideAnimation(View view, int duration) {
//Set the duration of the animation to the int we passed in
setDuration(duration);
//Set the view to be animated to the view we passed in
viewToBeAnimated = view;
//Get the Margin Parameters for the view so we can edit them
viewMarginParams = (MarginLayoutParams) view.getLayoutParams();
//If the view is VISIBLE, hide it after. If it's GONE, show it before we start.
hideAfter = (view.getVisibility() == View.VISIBLE);
//First off, start the margin at the bottom margin we've already set.
//You need your layout to have a negative margin for this to work correctly.
marginStart = viewMarginParams.bottomMargin;
//Decide if we're expanding or collapsing
if (marginStart == 0){
marginEnd = 0 - view.getHeight();
}
else {
marginEnd = 0;
}
//Make sure the view is visible for our animation
view.setVisibility(View.VISIBLE);
}
#Override
protected void applyTransformation(float interpolatedTime, Transformation t) {
super.applyTransformation(interpolatedTime, t);
if (interpolatedTime < 1.0f) {
// Setting the new bottom margin to the start of the margin
// plus the inbetween bits
viewMarginParams.bottomMargin = marginStart
+ (int) ((marginEnd - marginStart) * interpolatedTime);
// Request the layout as it happens so we can see it redrawing
viewToBeAnimated.requestLayout();
// Make sure we have finished before we mess about with the rest of it
} else if (!alreadyFinished) {
viewMarginParams.bottomMargin = marginEnd;
viewToBeAnimated.requestLayout();
if (hideAfter) {
viewToBeAnimated.setVisibility(View.GONE);
}
alreadyFinished = true;
}
hideAfter = false;
}
}
EDIT: If anyone had used this code before and found that if you click on the button that starts the animation more than once before the animation was finished, it would mess up the animation from then on, causing it to always hide the view after the animation finished. I missed the reset of the hideAfter boolean near the bottom of the code, added it now.

you can do this manually by using setvisibility feature on the event onClick()
or
use this
dynamically adding two views one below other

Android Animating multiple child views in series

Trying to add a help overlay to our app.
This overlay is a RelativeLayout with translucent background and it contains a few TextView and a few ImageView child elements. Now, i want each of the TextView / ImageView to fade-in one after another.
I am using a fade-in animation set (defined in the XML) and calling .startAnimation() on each view in the AnimationListener's OnAnimationEnd method. So, when the first View is done fading-in, i call the startAnimation method on the next view to be faded-in. I am using the same Animation object (animationFadeIn) as argument to startAnimation of all the views. Like so:
...
Animation animationFadeIn = AnimationUtils.loadAnimation(this.context, R.anim.fadein);
...
AnimationListener animationInListener = new AnimationListener(){
#Override
public void onAnimationEnd(Animation animation) {
animation_activity++;
switch(animation_activity) {
case SHOW_TEXT_DROP:
txtDrop.startAnimation(animationFadeIn);
break;
case SHOW_TEXT_SEND:
txtSend.startAnimation(animationFadeIn);
break;
case SHOW_IMAGE_TOUCH:
imgTouch.startAnimation(animationFadeIn);
break;
case SHOW_TEXT_DISABLE:
txtDisable.startAnimation(animationFadeIn);
break;
}
}
};
For fade-in animation, i referred this tutorial
Now, here's the problem:
First view fades-in
Second view fades-in, but first view fades-in again as well along with it
Same continues until all the views are done fading-in
Also, how do i add some delay before the next view fades-in setStartOffset ?
UPDATE
I noticed that if i create a second Animation object by
animationFadeIn2 = AnimationUtils.loadAnimation(this.context, R.anim.fadein);
and then use it for the startAnimation of other element, then it does not create this issue. So, i believe, there must be some property to be set on the Animation object so as to avoid this ?

I finally went ahead and created multiple Animation objects for each of the element. That solves the issue for time-being. It may not be the right/best approach.

Adding a view dynamically in a ClickListener

I am trying to add a View to a RelativeLayout in my OnClickListener.
montrolButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// myParent is a relative layout
// newChild is an ImageView
myParent.addView(newChild);
requestLayout();
}
});
I have looked at the HierarchyViewer, I don' see my new child being added.
Can you please tell me if I miss anything?

I just tried the very same code and it works as it should. There could be an issue with your variable myParent which is not the element you expect it to be.
Also I did not have to call requestLayout() for the added view to appear on the screen.
Possibly try to just explicitly get another part of your view and add it there to see what is happening. Also just to try, you may do this:
RelativeLayout rv = (RelativeLayout) this.findViewById(R.id.right3);
ProgressBar iv = new ProgressBar(this);
rv.addView(iv);
to see if there is anything wrong with your image view instead of myParent
In any case it works if both elements are OK - there is nothing else to do in an activity.

Do you set the layout attributes of the new view (image view)?