Develop Reference

Android Espresso GridView scroll to each item and perform a click on them

I have a GridView loaded with data, and some items in the grid are "group" items
that contain a different set of data. The GridView can scroll if there is
a lot of data.
On some devices the GridView has three columns and on others there are only two columns depending on the device screen width.
What I need to test is to scroll to a particular(with text) item in the grid, open it and then close it(back button=simpleClick). Then scroll to a second item with a particular text and open and then close it(back button=simpleClick).
I have tried several approaches with swipes, and then performing clicks
on them, but this approach fails as you need to know exactly how many
swipes/scrolls to perform before I can click to open the item group - device specific which is bad. Also performing too many scrolls than what is required to reach the bottom of the screen seems to slowdown the test !!quite!! a bit.
private void scrollDown() {
Log.d(TAG, "scrollDown: ");
onView(withId(R.id.main_grid))
.perform(swipeUp());
}
private void scrollUp() {
Log.d(TAG, "scrollUp: ");
onView(withId(R.id.main_grid))
.perform(swipeDown());
}
private void clickOn(final String text) {
onView(withText(new Matcher<String>() {
#Override
public boolean matches(Object item) {
if (item instanceof String) {
if (((String) item).contains(text))
return true;
else
return false;
}
return false;
}
#Override
public void describeMismatch(Object item, Description mismatchDescription) {
}
#Override
public void _dont_implement_Matcher___instead_extend_BaseMatcher_() {
}
#Override
public void describeTo(Description description) {
}
}))
.perform(click());
}
I have tried this as well, but focus gets set to each Item
but as it reaches the end of the screen, one needs to scroll manually
on the device - it does not scroll the screen.
for (int i = 0 ; i < 20; i++) {
onData(anything())
.inAdapterView(allOf(withId(R.id.main_grid), isDisplayed()))
.atPosition(i)
.check(matches(isDisplayed()));
}
I have also tried using the onData which I cannot get to succeed(compile/build),
as I am using a CursorLoader and a ResourceCursorAdapter.
Any Example to solve my test case would great.

Yes, you should use onData statement to avoid problems with scrolling in GridView. You can take a look at example here - http://droidtestlab.com/adapterView.html
But in your case you will have android.database.Cursor interface as a parameter to onData. Something like this (here you specify that you want to wait for data in GridView where first column is equal "VALUE" and then click at this record):
onData(allOf(is(new BoundedMatcher<Object, Cursor>(Cursor.class) {
#Override
public void describeTo(Description description) {
}
#Override
protected boolean matchesSafely(Cursor cursor) {
return cursor.getString(0).equals("VALUE");
}
}))).inAdapterView(withId(<ADAPTER_ID>)).perform(click());

Scroll a ListView to the top without any screen flickering

I have implemented a ListView that has the functionality that you see in many apps, where user scrolls to bottom and it loads more, that OnScrollListener is this:
public class OnScrolledToEndListener implements AbsListView.OnScrollListener
{
private int prevLast;
#Override
public void onScrollStateChanged(AbsListView absListView, int i)
{
}
#Override
public void onScroll(AbsListView absListView, int first, int visible, int total)
{
int last = first + visible;
if (last == total)
{
if (prevLast != last)
{
prevLast = last;
onScrolledToEnd();
}
}
}
public void onScrolledToEnd()
{
}
}
Now the problem is that when a user has scrolled to the bottom of a list, and hits the refresh button in my app, I want it to start over at the top of the list, because if it stays at the bottom of the list, then the scroll listener will immediately trigger. The best way I've found to solve this is by doing the following before executing the refresh:
mListView.setSelection(0);
mListView.post(
new Runnable()
{
#Override
public void run()
{
mListView.setVisibility(View.GONE);
mLoadingLayout.setVisibility(View.VISIBLE); //this is basically a progressbar
// do the refresh
}
}
);
But there is a slight flicker when the list scrolls to the top. Any ideas on how to make it look better?

I figured out the solution. Apparently setting the ListView to View.GONE makes it not update its layout, so I set it to View.INVISIBLE instead and it worked. I didn't even have to use a Runnable.
mListView.setSelection(0);
mListView.setVisibility(View.INVISIBLE);
mLoadingLayout.setVisibility(View.VISIBLE);

How to design android layout for this snapshot?

I am a new in android programming, I made a layout with this figure:
Now I want to know when one of these buttons clicked I should run an new activity or change visibility to false and show new layout without run a new activity, what is the best solution?
You consider that count of these buttons are more than ten.
I want show a text with image,..(when clicked) because that is a educational book and these buttons are chapters list of that book

for an example if you want to change only the layout then you could do something like this
FirstButton.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(final View v) {
FirstView();
}
});
/
void FirstView(){
setContentView(R.layout.yourOtherLayout);
// then declare the layout views here.
firstView=false;
}
you can do this in all the buttons just create different methods for each
to handle the Back Button you can declare Boolean variables and use If else Statement to loop through them for example
boolean firstView = true, secondView = true;
#Override
public void onBackPressed(){
if (firstView == false ){
then firstView Is Showing.
// show the view you want and set
firstView = true;
}else if (SO ON)...
else { super.OnBackPressed(); // exit }
}

Adding items to ListView, maintaining scroll position and NOT seeing a scroll jump

I'm building an interface similar to the Google Hangouts chat interface. New messages are added to the bottom of the list. Scrolling up to the top of the list will trigger a load of previous message history. When the history comes in from the network, those messages are added to the top of the list and should not trigger any kind of scroll from the position the user had stopped when the load was triggered. In other words, a "loading indicator" is shown at the top of the list:
Which is then replaced in-situ with any loaded history.
I have all of this working... except one thing that I've had to resort to reflection to accomplish. There are plenty of questions and answers involving merely saving and restoring a scroll position when adding items to the adapter attached to a ListView. My problem is that when I do something like the following (simplified but should be self-explanatory):
public void addNewItems(List<Item> items) {
final int positionToSave = listView.getFirstVisiblePosition();
adapter.addAll(items);
listView.post(new Runnable() {
#Override
public void run() {
listView.setSelection(positionToSave);
}
});
}
Then what the user will see is a quick flash to the top of the ListView, then a quick flash back to the right location. The problem is fairly obvious and discovered by many people: setSelection() is unhappy until after notifyDataSetChanged() and a redraw of ListView. So we have to post() to the view to give it a chance to draw. But that looks terrible.
I've "fixed" it by using reflection. I hate it. At its core, what I want to accomplish is reset the first position of the ListView without going through the rigamarole of the draw cycle until after I've set the position. To do that, there's a helpful field of ListView: mFirstPosition. By gawd, that's exactly what I need to adjust! Unfortunately, it's package-private. Also unfortunately, there doesn't appear to be any way to set it programmatically or influence it in any way that doesn't involve an invalidate cycle... yielding the ugly behavior.
So, reflection with a fallback on failure:
try {
Field field = AdapterView.class.getDeclaredField("mFirstPosition");
field.setAccessible(true);
field.setInt(listView, positionToSave);
}
catch (Exception e) { // CATCH ALL THE EXCEPTIONS </meme>
e.printStackTrace();
listView.post(new Runnable() {
#Override
public void run() {
listView.setSelection(positionToSave);
}
});
}
}
Does it work? Yes. Is it hideous? Yes. Will it work in the future? Who knows? Is there a better way? That's my question.
How do I accomplish this without reflection?
An answer might be "write your own ListView that can handle this." I'll merely ask whether you've seen the code for ListView.
EDIT: Working solution with no reflection based on Luksprog's comment/answer.
Luksprog recommended an OnPreDrawListener(). Fascinating! I've messed with ViewTreeObservers before, but never one of these. After some messing around, the following type of thing appears to work quite perfectly.
public void addNewItems(List<Item> items) {
final int positionToSave = listView.getFirstVisiblePosition();
adapter.addAll(items);
listView.post(new Runnable() {
#Override
public void run() {
listView.setSelection(positionToSave);
}
});
listView.getViewTreeObserver().addOnPreDrawListener(new OnPreDrawListener() {
#Override
public boolean onPreDraw() {
if(listView.getFirstVisiblePosition() == positionToSave) {
listView.getViewTreeObserver().removeOnPreDrawListener(this);
return true;
}
else {
return false;
}
}
});
}
Very cool.

As I said in my comment, a OnPreDrawlistener could be another option to solve the problem. The idea of using the listener is to skip showing the ListView between the two states(after adding the data and after setting the selection to the right position). In the OnPreDrawListener(set with listViewReference.getViewTreeObserver().addOnPreDrawListener(listener);) you'll check the current visible position of the ListView and test it against the position which the ListView should show. If those don't match then make the listener's method return false to skip the frame and set the selection on the ListView to the right position. Setting the proper selection will trigger the draw listener again, this time the positions will match, in which case you'd unregister the OnPreDrawlistener and return true.

I was breaking up my head until I found a solution similar to this.
Before adding a set of items you have to save top distance of the firstVisible item and after adding the items do setSelectionFromTop().
Here is the code:
// save index and top position
int index = mList.getFirstVisiblePosition();
View v = mList.getChildAt(0);
int top = (v == null) ? 0 : v.getTop();
// for (Item item : items){
mListAdapter.add(item);
}
// restore index and top position
mList.setSelectionFromTop(index, top);
It works without any jump for me with a list of about 500 items :)
I took this code from this SO post: Retaining position in ListView after calling notifyDataSetChanged

The code suggested by the question author works, but it's dangerous.
For instance, this condition:
listView.getFirstVisiblePosition() == positionToSave
may always be true if no items were changed.
I had some problems with this aproach in a situation where any number of elements were added both above and below the current element. So I came up with a sligtly improved version:
/* This listener will block any listView redraws utils unlock() is called */
private class ListViewPredrawListener implements OnPreDrawListener {
private View view;
private boolean locked;
private ListViewPredrawListener(View view) {
this.view = view;
}
public void lock() {
if (!locked) {
locked = true;
view.getViewTreeObserver().addOnPreDrawListener(this);
}
}
public void unlock() {
if (locked) {
locked = false;
view.getViewTreeObserver().removeOnPreDrawListener(this);
}
}
#Override
public boolean onPreDraw() {
return false;
}
}
/* Method inside our BaseAdapter */
private updateList(List<Item> newItems) {
int pos = listView.getFirstVisiblePosition();
View cell = listView.getChildAt(pos);
String savedId = adapter.getItemId(pos); // item the user is currently looking at
savedPositionOffset = cell == null ? 0 : cell.getTop(); // current item top offset
// Now we block listView drawing until after setSelectionFromTop() is called
final ListViewPredrawListener predrawListener = new ListViewPredrawListener(listView);
predrawListener.lock();
// We have no idea what changed between items and newItems, the only assumption
// that we make is that item with savedId is still in the newItems list
items = newItems;
notifyDataSetChanged();
// or for ArrayAdapter:
//clear();
//addAll(newItems);
listView.post(new Runnable() {
#Override
public void run() {
// Now we can finally unlock listView drawing
// Note that this code will always be executed
predrawListener.unlock();
int newPosition = ...; // Calculate new position based on the savedId
listView.setSelectionFromTop(newPosition, savedPositionOffset);
}
});
}

Android ListView clicking bottom item and increasing height of it

I have a listview where pople can click on items. When they do, they increase height and show more information.
However, when clicking the bottom item, it is not visible to the user that the item height has increased and there is content if you scroll down.
Using e.g. following code in onItemClick does not solve the problem:
if (position == myItemsDataArrayList.size() - 1) {
if (data.ui_flags == "clicked") {
catalogListView.smoothScrollToPosition(position);
}
}

Implement this function in your if statement.
private void scrollMyListViewToBottom() {
myListView.post(new Runnable() {
#Override
public void run() {
// Select the last row so it will scroll into view...
myListView.setSelection(myListAdapter.getCount() - 1);
}
});
}
code by: https://stackoverflow.com/a/7032341/2197087

Working code solution was this:
catalogListView.post(new Runnable() {
#Override
public void run() {
catalogListView.setSelection(position_final);
}
});