Develop Reference

Get the values from GridView items

I am working on a project where I have a let's say 5x5 grid of TextViews and I want to check if an entire row or column has equal elements. I am using an Adapter class to inflate my gridview with simply one textview element. Here is the code that I have tried but I cannot seem to make it work:
final int size = gridView.getCount(); //25
int temp = 0;
for (int i = 0; i < size; i++) {
ViewGroup gridChild = (ViewGroup) gridView.getChildAt(i);
childSize = gridChild.getChildCount();
for (int j = 0; j < childSize; j++) {
if (gridChild.getChildAt(j) instanceof TextView &&
((TextView) gridChild.getChildAt(j)).getText().toString().equals("x")) {
temp++;
}
The thing is when i tried to debug, debugger showed null values for childSize variable and could not properly get the value from getChildAt. Basically, what I am trying to do is get inside the if statement. Also this is the first time I am working with ViewGroup calss, and the methods that I call. Any help would be appreciated.
Edit:I am looking for a way to do this outside the getView method in the adapter class and not in a onClick method as well. (Code sample answers would be highly appreciated). Also, the getChildAt method call returns null so the code I have shown would not work because I am assigning a null value to the gridChild.
This is the onClick that I use for the TextViews:
`
public void numberFill(View view) {
if (((TextView) view).getText().toString().isEmpty()) {
((TextView) view).setText(String.valueOf(numbCounter + 1));
numbCounter++;
}
else if (!((TextView) view).getText().toString().isEmpty() && numbCounter >= 16) {
((TextView) view).setText("x");
}
}
This is my adapter class:
public class GridAdapter extends BaseAdapter {
private final Context mContext;
private String[] numbers;
public GridAdapter(Context context, String[] numbers) {
this.mContext = context;
this.numbers = numbers;
}
#Override
public int getCount() {
return numbers.length;
}
#Override
public long getItemId(int position) {
return 0;
}
#Override
public Object getItem(int position) {
return numbers[position];
//return null;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
LayoutInflater inflater = (LayoutInflater)
mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View gridView;
if (convertView == null) {
gridView = new View(mContext);
gridView = inflater.inflate(R.layout.textview_layout, null);
TextView textView = (TextView) gridView.findViewById(R.id.cell);
textView.setText(numbers[position]);
} else {
gridView = (View) convertView;
}
return gridView;
}
}
numberFill reworked:
public void numberFill(View view) {
int index = (Integer) view.getTag();
if (numbers[index].toString().isEmpty()) {
numbers[index] = String.valueOf(numbCounter + 1);
numbCounter++;
}
else if (!numbers[index].toString().isEmpty() && numbCounter >= 25) {
numbers[index] = "x";
}
gridAdapter.notifyDataSetChanged();
}
`

When using an AdapterView – such as your GridView – you generally don't want to directly access and manipulate its child Views outside of its Adapter. Instead, the dataset backing the Adapter should be updated, and the GridView then refreshed.
In your case, you presumably have a setup similar to this in your Activity:
private GridAdapter gridAdapter;
private String[] numbers;
#Override
protected void onCreate(Bundle savedInstanceState) {
...
numbers = new String[25];
gridAdapter = new GridAdapter(this, numbers);
}
Here, the numbers array is what you want to directly modify, rather than the text on the GridView's child TextViews. That array is then easily iterated over to do your row and column value checks.
Since the array will be modified in the Activity, we need a way to pass the clicked TextView's position in the Adapter to the Activity's click method, as we'll need it to access the correct array element. For this, we can utilize the tag property available on all View's, via the setTag() and getTag() methods. For example, in GridAdapter's getView() method:
...
TextView textView = (TextView) gridView.findViewById(R.id.cell);
textView.setText(numbers[position]);
textView.setTag(position);
...
In the click method, the position can be easily retrieved with getTag(), and used as the index to get the clicked TextView's text from the numbers array. You can then do the necessary processing or calculation with that text, set the modified value back to the array element, and trigger a refresh on the Adapter.
public void numberFill(View view) {
int index = (Integer) view.getTag();
// Do your processing with numbers[index]
numbers[index] = "new value";
gridAdapter.notifyDataSetChanged();
}
The notifyDataSetChanged() call will cause the GridView to update its children, and your new value will be set in the appropriate TextView. The numbers array now also has the current values, and is readily available in the Activity to perform the necessary checks there.

How to access the LayoutManager from the RecyclerView's ItemDecoration class?

I haven't been able to find any post about it...
We have the good old RecyclerView.ItemDecoration code (taken from Suleiman's Mansonry Github project):
public class SpacesItemDecoration extends RecyclerView.ItemDecoration {
private final int mSpace;
public SpacesItemDecoration(int space) {
this.mSpace = space;
}
#Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
outRect.left = mSpace;
outRect.right = mSpace;
outRect.bottom = mSpace;
// Add top margin only for the first item to avoid double space between items
if (parent.getChildAdapterPosition(view) == 0)
outRect.top = mSpace;
}
}
I want to have a condition that sets mSpace (offset/margin) depending on the current LayoutManager in the RecyclerView.
For example:
if(/* LayoutManager is LinearLayoutManager*/){
//Set larger margin
}else{
//Set lower margin
}

So... as I was re-reading the question to check if anything was missing, and I realized that you actually get a RecyclerView reference (parent) as an argument of getItemOffsets().
So you can just call parent.getLayoutManager() from inside the function.
Example:
#Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (parent.getLayoutManager() instanceof LinearLayoutManager){
margin = 2;
}else if (parent.getLayoutManager() instanceof StaggeredGridLayoutManager){
margin = 1;
}else{
margin = 0;
}
//Do magic
}

How to change background of non-visible buttons in GridView (Button adapter) from an activity

My code works only for visible views.
mGridView = (GridView) findViewById(R.id.gridView);
mGridView.setAdapter(new ButtonAdapter(this, list));
Method called when chronometer ticks:
public void setBackground(int i) {
Button button = (Button) mGridView.getChildAt(i);
button.setBackgroundResource(R.drawable.button_shape);
This method causes NPE because getChildAt cannot access non-visible childs.
I tried some solutions found here but no luck so far (android - listview get item view by position - this solution did not causes NPE but was changing background for more buttons in one tick)
What I need is to change first button background on first tick, second button on second tick.. and last button on last tick and stay consistent while scrolling.
My getView method in ButtonAdapter:
public View getView(final int position,
View convertView, ViewGroup parent) {
Button btn;
LayoutInflater inflater = LayoutInflater.from(mContext);
if (convertView == null) {
// if it's not recycled, initialize some attributes
btn = (Button) inflater.inflate(R.layout.button, parent, false);
int width = mContext.getResources().getDimensionPixelSize(R.dimen.gridView_param_width);
int height = mContext.getResources().getDimensionPixelSize(R.dimen.gridView_param_height);
GridView.LayoutParams params = new GridView.LayoutParams(width, height);
btn.setLayoutParams(params);
} else {
btn = (Button) convertView;
}
btn.setText(list.get(position).getName());
btn.setId(position);
btn.setTag(position);
btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
SetGridViewListener activity = (SetGridViewListener) mContext;
activity.onClickGridView(position);
Button btn = (Button)v;
btn.setBackgroundResource(R.drawable.button_shape_clicked);
btn.setClickable(false);
}
});
return btn;
}
I think my problem is in getView method which is probably not recycling well for my purpose.
Thanks in advance.

I have solved it already. I used ViewHolder pattern like here ListView subobject clickable confilct and this method to access buttons from my activity:
public View getViewByPosition(int pos, GridView gridView) {
final int firstListItemPosition = listView.getFirstVisiblePosition();
final int lastListItemPosition = firstListItemPosition + listView.getChildCount() - 1;
if (pos < firstListItemPosition || pos > lastListItemPosition ) {
return gridView.getAdapter().getView(pos, null, listView);
} else {
final int childIndex = pos - firstListItemPosition;
return gridView.getChildAt(childIndex);
}
}
(android - listview get item view by position)
If you would like my concrete solution, write in comment and I will add it.

Android RecyclerView smooth scroll to view that's animating their height

I have a RecyclerView with Expandable Child Views, when the child ViewGroup is clicked it inflates an amount of views animating the ViewGroup height from 0 to the measured viewgroup height, like the following gif:
The problem is: I'm calling smoothScrollToPosition on recyclerView, it smooth scroll to the view position, but it considers the current view height, which is still not expanded, in the above gif i'm touching on the under view of the recyclerview, which dont scroll to position because the view is already visible, but when i touch again (calling the smoothscrolltoposition again) it scroll the view to the correct position, because the view is already expanded.
Is there any approach to scroll the view to the top of screen or just scroll to make content visible?
For references:
This is the method called to inflate the views:
collapsible_content.removeAllViews();
for(int i = 0; i < 5; i++) {
View link_view = getLayoutInflater().inflate(R.layout.list_item_timeline_step_link, collapsible_content, false);
TextView text = (TextView) link_view.findViewById(R.id.step_link_text);
text.setText("Test");
collapsible_content.addView(link_view);
}
And this is my method to expand:
public void toggle() {
collapsible_content.measure(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
Animation a;
if (mExpanded) {
a = new ExpandAnimation(collapsible_content.getLayoutParams().height, 0);
} else {
a = new ExpandAnimation(collapsible_content.getLayoutParams().height, getMeasuredHeight());
}
a.setDuration(mAnimationDuration);
collapsible_content.startAnimation(a);
mExpanded = !mExpanded;
}
And the animation:
private class ExpandAnimation extends Animation {
private final int mStartHeight;
private final int mDeltaHeight;
public ExpandAnimation(int startHeight, int endHeight) {
mStartHeight = startHeight;
mDeltaHeight = endHeight - startHeight;
}
#Override
protected void applyTransformation(float interpolatedTime,
Transformation t) {
final int newHeight = (int) (mStartHeight + mDeltaHeight *
interpolatedTime);
collapsible_content getLayoutParams().height = newHeight;
if (newHeight <= 0) {
collapsible_content setVisibility(View.GONE);
} else {
collapsible_content setVisibility(View.VISIBLE);
}
collapsible_content requestLayout();
}
#Override
public boolean willChangeBounds() {
return true;
}
}

My solution was to constant check for view bottom within applyTransformation method, and compare it with RecyclerView height, if the bottom get higher than the RV height, i scroll by the diff values:
final int bottom = collapsible_content.getBottom();
final int listViewHeight = mRecyclerView.getHeight();
if (bottom > listViewHeight) {
final int top = collapsible_content.getTop();
if (top > 0) {
mRecyclerView.smoothScrollBy(0, Math.min(bottom - listViewHeight + mRecyclerView.getPaddingBottom(), top));
}
}
The trick was to use Math.min to get the view top, so it don't scroll up making the top not visible.
Solution based on ListViewAnimations

Add an animationlistener and start the scrolling of the recyclerview after the expanding animation is finished.

Iterating through viewgroup

Given a new screen in android i would like to iterate through all the viewgroups and views in order to discover all buttons,text fields, spinner etc... is this possible ?

I get the view count and then use that as a
counter to call getChildAt(int index)

This question may have been long answered, but I wrote this recursive function to set onClickListeners for any buttons I find in my layout, but it could be repurposed:
private void recurseViews(ViewGroup v) {
View a;
boolean isgrp = false;
for(int i = 0; i < v.getChildCount(); i++) { //attach listener to all buttons
a = v.getChildAt(i);
if(a instanceof ViewGroup) setcl((ViewGroup) a);
else if(a != null) {
//do stuff with View a
}
}
return;
}
EDIT: Casting a View as ViewGroup does not raise an exception as had I previously thought, so the code is much shorter now

You could use this to get all child views inside a parent layout, returns an array list of views.
public List<View> getAllViews(ViewGroup layout){
List<View> views = new ArrayList<>();
for(int i =0; i< layout.getChildCount(); i++){
views.add(layout.getChildAt(i));
}
return views;
}
if you want to get a specific view you can use this example. It takes all TextView inside a layout.
public List<TextView> getAllTextViews(ViewGroup layout){
List<TextView> views = new ArrayList<>();
for(int i =0; i< layout.getChildCount(); i++){
View v =layout.getChildAt(i);
if(v instanceof TextView){
views.add((TextView)v);
}
}
return views;
}
As long as the object you're trying to get derives from View class, it will work.