Develop Reference

How to show fixed count of items in Recyclerview?

I have a task to show fixed count of items on the screen.
It doens't mean that I have fixed size of list, it means that only 5 items should be visible when scrolling.
How it can be done?
I didn't find any useful information about it.

I also encountered a similar problem. I have solved it almost perfectly. I chose to extend LinearLayoutManager.
public class MaxCountLayoutManager extends LinearLayoutManager {
private int maxCount = -1;
public MaxCountLayoutManager(Context context) {
super(context);
}
public MaxCountLayoutManager(Context context, int orientation, boolean reverseLayout) {
super(context, orientation, reverseLayout);
}
public MaxCountLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
public void setMaxCount(int maxCount) {
this.maxCount = maxCount;
}
#Override
public void setMeasuredDimension(int widthSize, int heightSize) {
int maxHeight = getMaxHeight();
if (maxHeight > 0 && maxHeight < heightSize) {
super.setMeasuredDimension(widthSize, maxHeight);
}
else {
super.setMeasuredDimension(widthSize, heightSize);
}
}
private int getMaxHeight() {
if (getChildCount() == 0 || maxCount <= 0) {
return 0;
}
View child = getChildAt(0);
int height = child.getHeight();
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
height += lp.topMargin + lp.bottomMargin;
return height*maxCount+getPaddingBottom()+getPaddingTop();
}
}
How to use:
# in kotlin
rcyclerView.layoutManager = MaxCountLayoutManager(context).apply { setMaxCount(5) }
But the height of each item needs to be the same, because I only considered the height and margin of the first item.

If i am getting your question correctly, you are trying to show a fixed number of list items on the screen, whenever the user stops scrolling.
This can be done by calculating screen height/width and then setting your list item layout dimensions(height/width), accordingly.
view.getLayoutParams().width = getScreenWidth() / VIEWS_COUNT_TO_DISPLAY;
Now, depending on whether you want a horizontal or a vertical list, change width or height values of your list item layout.
Check these links
RecyclerView number of visible items
How to show exact number of items in RecyclerView?

Simplest solution is to have onBindViewHolder() set its views height/width dynamically. For vertical list:
float containerHeight = mRecyclerView.getHeight();
holder.itemView.setMinimumHeight(Math.round(containerHeight/5));

Android: designing the view for a calendar app

I'm writing a calendar application for Android. The calendar needs to a have a day display similar to the default application, or MS outlook: a grid showing a line for each hour, and the appointments shown as rectangles.
Here's a similar sample image from Google Images:
I downloaded the source code for the calendar app from Google's Android Open Source Project, and saw that they implemented this display as a custom view which simplay uses Canvas.drawRect() to draw the rectangles, and then they implemented their own hit-test when the user clicks, to see which appointment was clicked.
I already wrote some of that stuff on my own and it works great, and isn't too complicated.
The problem is that I need the different lines of text inside the rectangles (the subject, the time) to be links to various functionality, and I'm wondering how I can do that.
When I draw, I already create Rects for each appointment. I was thinking I could create Rects for each piece of text as well, cache all of these in an ArrayList, and then perform the histtest against the cached rects. I'm only afraid this whole thing will be too heavy... does this sound like a solid design?
Or should I avoid the custom drawing altogether and programmatically generate and place views (TextViews maybe?) I'm an Android novice and I'm not sure what my options are...
Thanks for helping out!

Alright, as announced, here some example:
If you just use a custom view, you have to keep lists of objects and draw them yourself, as opposed to a custom layout where you just have to measure and layout the children. Since you can just add a button, there's no need to use hit-tests or whatsoever, since if you don't mess up the view will just receive the onClick() call.
Also, you can easily preview your layout in the editor if you correctly implement layout parameters. Which makes development much faster.
E.g. you can define your own layout parameters
<resources>
<declare-styleable name="TimeLineLayout_Layout">
<attr name="time_from" format="string"/>
<attr name="time_to" format="string"/>
</declare-styleable>
</resources>
Then use them like this...
<com.github.bleeding182.timelinelayout.TimeLineLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#22662222">
<TextView
android:layout_width="80dp"
android:layout_height="wrap_content"
android:background="#android:color/holo_green_dark"
android:padding="8dp"
android:text="12:00 - 16:00"
app:time_from="12:00"
app:time_to="16:00"/>
</com.github.bleeding182.timelinelayout.TimeLineLayout>
And the result would look something like this (I know it's ugly, but I made this just for testing :/ )
To do this, you create a basic layout where you measure and layout the views. You can then add any views to your layout, and by setting a time from / to and correctly measuring / layouting you can easily display all sorts of items.
The code for the screenshot is attached below, onDraw will create those ugly hour/half hour lines. onMeasure is for calculating view heights and onLayout is drawing the views to their correct time slot.
I hope this helps, it's sure easier to use than handling everything in one view.
public class TimeLineLayout extends ViewGroup {
private int tIntervalSpan = 24 * 60;
private float mMeasuredMinuteHeight;
public TimeLineLayout(Context context) {
super(context);
}
public TimeLineLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public TimeLineLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#TargetApi(Build.VERSION_CODES.LOLLIPOP)
public TimeLineLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
for (int i = 0; i < getChildCount(); i++) {
final View child = getChildAt(i);
ViewGroup.LayoutParams layoutParams = child.getLayoutParams();
if (layoutParams instanceof LayoutParams) {
LayoutParams params = (LayoutParams) layoutParams;
final int top = (int) (params.tFrom * mMeasuredMinuteHeight);
child.layout(l, top, child.getMeasuredWidth(), top + child.getMeasuredHeight());
}
}
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(heightMeasureSpec));
mMeasuredMinuteHeight = getMeasuredHeight() / (float) tIntervalSpan;
for (int i = 0; i < getChildCount(); i++) {
final View child = getChildAt(i);
ViewGroup.LayoutParams layoutParams = child.getLayoutParams();
if (layoutParams instanceof LayoutParams) {
LayoutParams params = (LayoutParams) layoutParams;
child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec((int) ((params.tTo - params.tFrom) * mMeasuredMinuteHeight), MeasureSpec.EXACTLY));
}
}
}
#Override
protected void onDraw(Canvas canvas) {
final float height = mMeasuredMinuteHeight * 60;
Paint paint = new Paint();
paint.setColor(Color.RED);
for(int i = 0; i < 24; i++) {
paint.setStrokeWidth(2f);
paint.setAlpha(255);
canvas.drawLine(0, i * height, getMeasuredWidth(), i*height, paint);
if(i < 23) {
paint.setStrokeWidth(1f);
paint.setAlpha(50);
canvas.drawLine(0, i * height + 30 * mMeasuredMinuteHeight, getMeasuredWidth(), i * height + 30 * mMeasuredMinuteHeight, paint);
}
}
}
#Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof LayoutParams;
}
#Override
public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
return new LayoutParams(getContext(), attrs);
}
public static class LayoutParams extends ViewGroup.LayoutParams {
private final int tFrom;
private final int tTo;
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
TypedArray a = c.obtainStyledAttributes(attrs, R.styleable.TimeLineLayout_Layout);
final String from = a.getString(R.styleable.TimeLineLayout_Layout_time_from);
final String to = a.getString(R.styleable.TimeLineLayout_Layout_time_to);
a.recycle();
tFrom = Integer.parseInt(from.split(":")[0]) * 60 + Integer.parseInt(from.split(":")[1]);
tTo = Integer.parseInt(to.split(":")[0]) * 60 + Integer.parseInt(to.split(":")[1]);
}
}

Weight sum and square form

I have LinearLayout which contains two Button widgets with layout_weight=1. Depends on length of Button's text or screen resolution I get buttons with rectangular form (gray rectangles) but I need to keep the square form (blue squares).
I was trying to change height of LinearLayout param in onStart() method, depends on Button's width, but getWidth() returns 0. I understand that it's because view at that moment still not rendered. Please, help me to solve my problem.

There are many ways to achieve this. If you need to find the real width of an element, you can:
1) attach an OnGlobalLayoutListener to the view's ViewTreeObserver (but remember to remove it when you are done)
2) or you can manually measure what you need:
if(view.getMeasuredHeight() == 0){
WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics metrics = new DisplayMetrics();
manager.getDefaultDisplay().getMetrics(metrics);
view.measure( metrics.widthPixels, metrics.heightPixels );
}
int realHeight = view.getMeasuredHeight();
//...your code

You are exactly right because at that time view will not be drawn so for that you have to use viewtreeobserver:
like this:
final ViewTreeObserver treeObserver = viewToMesure
.getViewTreeObserver();
treeObserver
.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
// TODO Auto-generated method stub
System.out.println(viewToMesure.getHeight()
+ "SDAFASFASDFas");
heith = viewToMesure.getHeight();
}
});
this view tree observer will be called after creating the view based on that you calculate and you can change.

You can use a custom view to set the view's height to be tha same as its width by overriding onMeasure:
public class SquareButton extends Button {
public SquareButton (Context context) {
super(context);
}
public SquareButton (Context context, AttributeSet attrs) {
super(context, attrs);
}
public SquareButton (Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), getMeasuredWidth());
}
}
All you have to is use the custom button in your xml layout and you don't have to do anything in the activity:
<com.package.name.SquareButton
android:layout_with="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" />

How to make textView wrap its multiline content exactly?

How can I make the textview wrap such text exactly ?
android:width attribute is not a solution, because the text is dynamic.
Desired behaviour
|Adcs |
|adscfd|
Current behavour:
|Adcs |
|adscfd |
Hereis the code (styles of TextViews only define things like textColor, textSize, textStyle).
<TextView
android:id="#+id/text_title_holder"
style="#style/TextBold.Black.Title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:maxWidth="100dp"
android:maxLines="2"
android:text="Adcs adscfd"
android:gravity="left"
android:visibility="visible" />
The topic wrap_content width on mutiline TextView has no good answer.

I have faced this problem and didn't find the solution in internet. I did this trick by creating the new component TightTextView that remeasures the given text in case you have specified the maxWidth of the component and the width of Layout (of text) is less that the measured width of the view.
package com.client.android.app.views;
import android.content.Context;
import android.text.Layout;
import android.util.AttributeSet;
import android.widget.TextView;
/**
* Tightly wraps the text when setting the maxWidth.
* #author sky
*/
public class TightTextView extends TextView {
private boolean hasMaxWidth;
public TightTextView(Context context) {
this(context, null, 0);
}
public TightTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public TightTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (hasMaxWidth) {
int specModeW = MeasureSpec.getMode(widthMeasureSpec);
if (specModeW != MeasureSpec.EXACTLY) {
Layout layout = getLayout();
int linesCount = layout.getLineCount();
if (linesCount > 1) {
float textRealMaxWidth = 0;
for (int n = 0; n < linesCount; ++n) {
textRealMaxWidth = Math.max(textRealMaxWidth, layout.getLineWidth(n));
}
int w = Math.round(textRealMaxWidth);
if (w < getMeasuredWidth()) {
super.onMeasure(MeasureSpec.makeMeasureSpec(w, MeasureSpec.AT_MOST),
heightMeasureSpec);
}
}
}
}
}
#Override
public void setMaxWidth(int maxpixels) {
super.setMaxWidth(maxpixels);
hasMaxWidth = true;
}
#Override
public void setMaxEms(int maxems) {
super.setMaxEms(maxems);
hasMaxWidth = true;
}
}
!!! Just did port it to older android APIs, cuz getMaxWidth() is only available since API level 16.

This question is a little old now but I too had this problem where I wanted green text in a black box over a mapView and got around it by putting my textView in a RelativeLayout container. I then used padding to set the border size. The textView now hugs the text nicely.
My outline in eclipse looks like this.
RelativeLayout
mapview
LinearLayout
RelativeLayout
textView1 << this is the box I want to hug the text
imageView1
RelativeLayout
etc....
Hope this helps.

GridView rows overlapping: how to make row height fit the tallest item?

Like this previous person, I have unwanted overlap between GridView items:
Notice the text, in every column except the rightmost one.
Where I differ from that previous question is that I don't want a constant row height. I want the row height to vary to accommodate the tallest content in each row, for efficient use of screen space.
Looking at the source for GridView (not the authoritative copy, but kernel.org is still down), we can see in fillDown() and makeRow() that the last View seen is the "reference view": the row's height is set from the height of that View, not from the tallest one. This explains why the rightmost column is ok. Unfortunately, GridView is not well set-up for me to fix this by inheritance. All the relevant fields and methods are private.
So, before I take the well-worn bloaty path of "clone and own", is there a trick I'm missing here? I could use a TableLayout, but that would require me to implement numColumns="auto_fit" myself (since I want e.g. just one long column on a phone screen), and it also wouldn't be an AdapterView, which this feels like it ought to be.
Edit: in fact, clone and own is not practical here. GridView depends on inaccessible parts of its parent and sibling classes, and would result in importing at least 6000 lines of code (AbsListView, AdapterView, etc.)

I used a static array to drive max heights for the row. This is not perfect since the earlier columns will not be resized until the cell is redisplayed. Here is the code for the inflated reusable content view.
Edit: I got this work correctly but I had pre-measure all cells before rendering. I did this by subclassing GridView and adding a measuring hook in the onLayout method.
/**
* Custom view group that shares a common max height
* #author Chase Colburn
*/
public class GridViewItemLayout extends LinearLayout {
// Array of max cell heights for each row
private static int[] mMaxRowHeight;
// The number of columns in the grid view
private static int mNumColumns;
// The position of the view cell
private int mPosition;
// Public constructor
public GridViewItemLayout(Context context) {
super(context);
}
// Public constructor
public GridViewItemLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
/**
* Set the position of the view cell
* #param position
*/
public void setPosition(int position) {
mPosition = position;
}
/**
* Set the number of columns and item count in order to accurately store the
* max height for each row. This must be called whenever there is a change to the layout
* or content data.
*
* #param numColumns
* #param itemCount
*/
public static void initItemLayout(int numColumns, int itemCount) {
mNumColumns = numColumns;
mMaxRowHeight = new int[itemCount];
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// Do not calculate max height if column count is only one
if(mNumColumns <= 1 || mMaxRowHeight == null) {
return;
}
// Get the current view cell index for the grid row
int rowIndex = mPosition / mNumColumns;
// Get the measured height for this layout
int measuredHeight = getMeasuredHeight();
// If the current height is larger than previous measurements, update the array
if(measuredHeight > mMaxRowHeight[rowIndex]) {
mMaxRowHeight[rowIndex] = measuredHeight;
}
// Update the dimensions of the layout to reflect the max height
setMeasuredDimension(getMeasuredWidth(), mMaxRowHeight[rowIndex]);
}
}
Here is the measuring function in my BaseAdapter subclass. Note that I have a method updateItemDisplay that sets all appropriate text and images on the view cell.
/**
* Run a pass through each item and force a measure to determine the max height for each row
*/
public void measureItems(int columnWidth) {
// Obtain system inflater
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
// Inflate temp layout object for measuring
GridViewItemLayout itemView = (GridViewItemLayout)inflater.inflate(R.layout.list_confirm_item, null);
// Create measuring specs
int widthMeasureSpec = MeasureSpec.makeMeasureSpec(columnWidth, MeasureSpec.EXACTLY);
int heightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
// Loop through each data object
for(int index = 0; index < mItems.size(); index++) {
String[] item = mItems.get(index);
// Set position and data
itemView.setPosition(index);
itemView.updateItemDisplay(item, mLanguage);
// Force measuring
itemView.requestLayout();
itemView.measure(widthMeasureSpec, heightMeasureSpec);
}
}
And finally, here is the GridView subclass set up to measure view cells during layout:
/**
* Custom subclass of grid view to measure all view cells
* in order to determine the max height of the row
*
* #author Chase Colburn
*/
public class AutoMeasureGridView extends GridView {
public AutoMeasureGridView(Context context) {
super(context);
}
public AutoMeasureGridView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public AutoMeasureGridView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if(changed) {
CustomAdapter adapter = (CustomAdapter)getAdapter();
int numColumns = getContext().getResources().getInteger(R.integer.list_num_columns);
GridViewItemLayout.initItemLayout(numColumns, adapter.getCount());
if(numColumns > 1) {
int columnWidth = getMeasuredWidth() / numColumns;
adapter.measureItems(columnWidth);
}
}
super.onLayout(changed, l, t, r, b);
}
}
The reason I have the number of columns as a resource is so that I can have a different number based on orientation, etc.

Based on the info from Chris, I used this workaround making use of the reference-View used by the native GridView when determining the height of other GridView items.
I created this GridViewItemContainer custom class:
/**
* This class makes sure that all items in a GridView row are of the same height.
* (Could extend FrameLayout, LinearLayout etc as well, RelativeLayout was just my choice here)
* #author Anton Spaans
*
*/
public class GridViewItemContainer extends RelativeLayout {
private View[] viewsInRow;
public GridViewItemContainer(Context context) {
super(context);
}
public GridViewItemContainer(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public GridViewItemContainer(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setViewsInRow(View[] viewsInRow) {
if (viewsInRow != null) {
if (this.viewsInRow == null) {
this.viewsInRow = Arrays.copyOf(viewsInRow, viewsInRow.length);
}
else {
System.arraycopy(viewsInRow, 0, this.viewsInRow, 0, viewsInRow.length);
}
}
else if (this.viewsInRow != null){
Arrays.fill(this.viewsInRow, null);
}
}
#Override
protected LayoutParams generateDefaultLayoutParams() {
return new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (viewsInRow == null) {
return;
}
int measuredHeight = getMeasuredHeight();
int maxHeight = measuredHeight;
for (View siblingInRow : viewsInRow) {
if (siblingInRow != null) {
maxHeight = Math.max(maxHeight, siblingInRow.getMeasuredHeight());
}
}
if (maxHeight == measuredHeight) {
return;
}
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
switch(heightMode) {
case MeasureSpec.AT_MOST:
heightMeasureSpec = MeasureSpec.makeMeasureSpec(Math.min(maxHeight, heightSize), MeasureSpec.EXACTLY);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
break;
case MeasureSpec.EXACTLY:
// No debate here. Final measuring already took place. That's it.
break;
case MeasureSpec.UNSPECIFIED:
heightMeasureSpec = MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.EXACTLY);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
break;
}
}
In your adapter's getView method, either wrap your convertView as a child in a new GridViewItemContainer or make this one the top XML element of your item layout:
// convertView has been just been inflated or came from getView parameter.
if (!(convertView instanceof GridViewItemContainer)) {
ViewGroup container = new GridViewItemContainer(inflater.getContext());
// If you have tags, move them to the new top element. E.g.:
container.setTag(convertView.getTag());
convertView.setTag(null);
container.addView(convertView);
convertView = container;
}
...
...
viewsInRow[position % numColumns] = convertView;
GridViewItemContainer referenceView = (GridViewItemContainer)convertView;
if ((position % numColumns == (numColumns-1)) || (position == getCount()-1)) {
referenceView.setViewsInRow(viewsInRow);
}
else {
referenceView.setViewsInRow(null);
}
Where numColumns is the number of columns in the GridView and 'viewsInRow' is an list of View on the current row of where 'position' is located.

I did so many research but found incomplete answer or had tough with understanding what going on with solution but finally found an answer that fit perfectly with proper explanation.
My problem was to fit gridview item into height properly. This Grid-view worked great when all of your views are the same height. But when your views have different heights, the grid doesn't behave as expected. Views will overlap each other, causing an an-aesthetically pleasing grid.
Here Solution I used this class in XML layout.
I used this solution, and this is working very well, thanks a lot.--Abhishek Mittal

If you convert your GridView or ListView to a RecyclerView, this issue will not happen. And you won't need to make a custom GridView class.

This is not the correct solution which I am mentioned below, but can be workaround depends on your requirement.
Just set the height of view fix(in some dp i.e.- 50dp) from your child layout of gridview, so that it can be Wrapped.
<TextView
android:layout_width="match_parent"
android:layout_height="50dp"
android:ellipsize="end"
android:textColor="#color/text_color"
android:textSize="13dp"
android:textStyle="normal" />

Giving weight to your GridView also works on GridViews inside LinearLayouts as a child. This way GridView fills the viewport with its children so you are able to view it's items as long as they fit the screen (then you scroll).
But always avoid using GridViews inside ScrollViews. Otherwise you will need to calculate each child's height and reassign them as Chase answered above.
<GridView
android:id="#+id/gvFriends"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:verticalSpacing="5dp"
android:horizontalSpacing="5dp"
android:clipChildren="false"
android:listSelector="#android:color/transparent"
android:scrollbarAlwaysDrawHorizontalTrack="false"
android:scrollbarAlwaysDrawVerticalTrack="false"
android:stretchMode="columnWidth"
android:scrollbars="none"
android:numColumns="4"/>