Develop Reference

Set Layout width percentage of the total screen width

Is there's way to set Button width 50% of the total screen size (from java code).
I have found a few answers but i would like to change Button size with java code instead of XML.

Try this out..
DisplayMetrics metrics = new DisplayMetrics();
getActivity().getWindowManager().getDefaultDisplay().getMetrics(metrics);
int height = metrics.heightPixels;
ViewGroup.LayoutParams params = yourButton.getLayoutParams();
params.width = metrics.widthPixels;
try {
double ratio = 0.5;
params.height = Double.valueOf(ratio * height).intValue();
yourButton.setLayoutParams(params);
} catch (Exception e) {
e.printStackTrace();
}

Many ways to achieve this, you could try like below:
Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int width = size.x;
ViewGroup.LayoutParams params= yourBtn.getLayoutParams();
params.width= width * 1/2;
yourBtn.setLayoutParams(params);
yourBtn.requestLayout();

It's so simple just do.
button.getLayoutParams().width = Resources.getSystem().getDisplayMetrics().widthPixels/2;

I hope it Helps
possible with of Guideline constraint
Guideline
Utility class representing a Guideline helper object for
ConstraintLayout. Helper objects are not displayed on device (they are
marked as View.GONE) and are only used for layout purposes. They only
work within a ConstraintLayout.
A Guideline can be either horizontal or vertical:
Vertical Guidelines have a width of zero and the height of their
ConstraintLayout parent Horizontal Guidelines have a height of zero
and the width of their ConstraintLayout parent Positioning a Guideline
is possible in three different ways:
specifying a fixed distance from the left or the top of a layout
(layout_constraintGuide_begin) specifying a fixed distance from the
right or the bottom of a layout (layout_constraintGuide_end)
specifying a percentage of the width or the height of a layout
(layout_constraintGuide_percent) Widgets can then be constrained to
a Guideline, allowing multiple widgets to be positioned easily from
one Guideline, or allowing reactive layout behavior by using percent
positioning.
See the list of attributes in ConstraintLayout.LayoutParams to set a
Guideline in XML, as well as the corresponding
ConstraintSet.setGuidelineBegin(int, int),
ConstraintSet.setGuidelineEnd(int, int) and
ConstraintSet.setGuidelinePercent(int, float) functions in
ConstraintSet.
<android.support.constraint.Guideline
android:id="#+id/guideline3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.50" />
**
Example
**
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.constraint.Guideline
android:id="#+id/guideline3"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.50" />
<TextView
android:id="#+id/textView3"
android:layout_width="wrap_content"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
android:text="TextView"
app:layout_constraintBottom_toTopOf="#+id/guideline4"
app:layout_constraintTop_toTopOf="#+id/guideline3"
tools:layout_editor_absoluteX="104dp" />
<android.support.constraint.Guideline
android:id="#+id/guideline4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.80" />
</android.support.constraint.ConstraintLayout>
Example with Layout height 50% of screen
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginBottom="8dp"
android:layout_marginTop="8dp"
app:layout_constraintBottom_toTopOf="#+id/guideline4"
app:layout_constraintTop_toTopOf="parent">
</RelativeLayout>
<android.support.constraint.Guideline
android:id="#+id/guideline4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
app:layout_constraintGuide_percent="0.50" />
2nd Way
getDefaultDisplay ()
public abstract Display getDefaultDisplay () Returns the Display upon
which this WindowManager instance will create new windows.
Despite the name of this method, the display that is returned is not
necessarily the primary display of the system (see
Display.DEFAULT_DISPLAY). The returned display could instead be a
secondary display that this window manager instance is managing. Think
of it as the display that this WindowManager instance uses by default.
To create windows on a different display, you need to obtain a
WindowManager for that Display. (See the WindowManager class
documentation for more information.)
Display mDisplay = getWindowManager().getDefaultDisplay();
final int width = mDisplay.getWidth();
final int height = mDisplay.getHeight();
// now simple height/2 use it as u want

something like this perhaps? Not sure if it will work exactly as you want it but thats the general idea of it
Configuration configuration = getActivity().getResources().getConfiguration();
int screenWidthDp = configuration.screenWidthDp;
final float scale = context.getResources().getDisplayMetrics().density;
int pixels = (int) (screenWidthDp * scale);
button1.setWidth(pixels*0.5);

Try
LayoutParams params = new LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.setMargins(left, top, right, bottom);
yourbutton.setLayoutParams(params);
Resources r = mContext.getResources();
int px = (int) TypedValue.applyDimension(
TypedValue.COMPLEX_UNIT_DIP,
yourdpmeasure,
r.getDisplayMetrics());

How can I make a HorizontalScrollView's child's child have the width of the screen?

So I've got a LinearLayout, that has the layout_width set to "match_parent", let's call that A.
Then there's a HorizontalScrollView within that, let's call that B.
Then there's a RelativeLayout within that, that I am using because of the rule that only allows 1 direct child int he scroll view, lets call that C.
Then within that I have multiple RelativeLayouts that I want to make the same width as A, alongside each other. Please help me with how I can accomplish this!
Here is the XML code:
<LinearLayout
android:id="#+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/white"
android:orientation="vertical" >
<HorizontalScrollView
android:id="#+id/scrollView"
android:layout_width="match_parent"
android:layout_height="0dp"
android:fillViewport="true"
android:layout_weight="9">
// Used because ScrollView can have only 1 child.
<RelativeLayout
android:id="#+id/directChild"
android:layout_width="wrap_content"
android:layout_height="match_parent">
// This is the RelativeLayout that I want to fill the screen width with.
<RelativeLayout
android:id="#+id/howToMakeScreenWidth"
android:layout_width="385dp"
android:layout_height="match_parent">

Find width of screen using below utility method.
Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int width = size.x;
then assign that width to your child RelativeLayout
RelativeLayout.LayoutParams relParams = new RelativeLayout.LayoutParams(
width, ViewGroup.LayoutParams.WRAP_CONTENT);
yourRelativeLayout.setLayoutParams(relParams);

How to write XML code for width and heigh in Java

XML code
<ImageView
android:layout_width="match_parent"
android:layout_height="200dp"
android:id="#+id/imageView"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:background="#drawable/pz"
android:layout_marginTop="5dp" />
I wrote it like this in java
ImageView imageView = new ImageView(MainActivity.this);
imageView.setImageResource(R.drawable.pz);
DisplayMetrics displaymetrics = new DisplayMetrics();
MainActivity.this.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int width = displaymetrics.widthPixels;
int height = 300;
imageView.setLayoutParams(new ViewGroup.LayoutParams(width, height));
imageView.setId(i + 1);
li.addView(imageView);
But it looks strange , i want to change height to eg. 200 , instead of changing height it change width.Is there any better way to make it i just want width to MATCH_PARENT and height to be 200dp?

if you want to set any layout parameter to wrap_content or match_parent you should set ViewGroup.LayoutParams.MATCH_PARENT orViewGroup.LayoutParams.MATCH_PARENT constants for constructor parameters
and the constructor gets parameters in px so you have to change it to dp you can use this link

Android getMeasuredHeight get wrong value

I have the XML like this:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000000" >
<com.XXXXXXXXXXX.view
android:layout_width="200dp"
android:background="#ffffff"
android:layout_height="400dp"
android:layout_centerInParent="true" />
I get the view height in the method onMesure like this:
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (!isMeasured)
{
isMeasured = true;
mViewHeight = getMeasuredHeight();
mViewWidth = getMeasuredWidth();...}
the mViewWidth is right(600px), but the mViewHeight is wrong(1626px).
Could someone give me some pointers?
Tks a lot.

getMeasuredHeight() will return the desired height for the child, not necessarily the height it actually gets. You also are taking the first measured value and setting your width/height to that. onMeasure can be called multiple times for different reasons. The intent is to say how much height/width your view desires with the given MeasureSpec constraints. onLayout will get called later with where your parent actually wants you, which may not match what you asked for in onMeasure.
Also, views already have a getWidth() and getHeight() which are valid after the layout pass. Do you need your own mViewWidth and mViewHeight?

How do you use a custom view in a HorizontalScrollView?

I've got a custom view (called CustomStrechView) which extends an ImageView. The point of this view is so that I can get an image to fill the view without losing the aspect ratio.
Now the CustomStrechView works fine when I use it in most applications, but when I try to apply it within my HorizontalScrollView, the images all seem to disappear. I'm not sure why this happens. I've tried removing the <HorizontalScrollView /> and when I do the images show back up, so I feel there is some property that needs to be set, but I can't seem to find it.
Can anyone point out what I’m doing wrong or a better way to get a custom view to work in a HorizontalScrollView?
Edit:
After playing around with this for a bit, I've determined that I can get the custom view to show the image only if I hardcode the width dimension, ie:
<com.example.dragdropshapes.CustomStrechView
android:layout_width="200dp"
Leaving the height as fill_parent is fine...
Code:
Here's how my custom view is being used in the xml file:
<!-- Removing this makes the images show up -->
<HorizontalScrollView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:fillViewport="true"
android:layout_marginTop="50dp">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:showDividers="middle"
android:orientation="horizontal">
<!-- Changing this to a normal ImageView makes the image show up -->
<com.example.dragdropshapes.CustomStrechView
android:id="#+id/pickshapes"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:clickable="true"
android:onClick="pickShapes"
android:background="#drawable/border"
android:src="#drawable/ic_launcher"
/>
<!-- There are 5 other custom ImageViews here -->
</LinearLayout>
</HorizontalScrollView>
Here's the major part of the custom view code:
public class CustomStrechView extends ImageView{
private final Drawable srcPic;
private final String TAG = "strechyTag";
private boolean changeSize = false;
private int Xpx;
private int Ypx;
public CustomStrechView(Context context) {
super(context);
srcPic = this.getDrawable();
}
//... other constructors, not really important...
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
Log.d(TAG, "in the onMeasure!!\n");
int width, height;
width = MeasureSpec.getSize(widthMeasureSpec);
height = width * srcPic.getIntrinsicHeight() / srcPic.getIntrinsicWidth();
setMeasuredDimension(width, height);
}
}

Through some debugging I was able to at least partially solve this myself. Turns out that the width acquired from the MeasureSpec.getSize(widthMeasureSpec); call was 0. Thus the calculation ended in width and height being 0 and the setMeasuredDimension call would then make the image invisible.
Now I'm saying I have this partially solved, because I still don't understand why I was getting that value of 0. I think it's because in a HorizontalScrollView the width isn't determined (it depends on the content within) thus whatever MeasureSpec.getSize(widthMeasureSpec); is actually doing is talking to the parent, and the parent in a normal Linear or RelativeLayout has a defined width where as in a HorizontalScrollView it does not... but that's just speculation at this point.
So I made a fix for it, if the width is 0 we run the calculation via the height instead. The height needed two cases to cover it to avoid divide by 0 errors (the else if and the else collectively).
Here's my current solution with the same xml file I noted in the Question.
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
if(width > 0)
height = width * srcPic.getIntrinsicHeight() / srcPic.getIntrinsicWidth();
else if(srcPic.getIntrinsicWidth() < srcPic.getIntrinsicHeight())
width = height / (srcPic.getIntrinsicHeight() / srcPic.getIntrinsicWidth());
else
width = height / (srcPic.getIntrinsicWidth() / srcPic.getIntrinsicHeight());
setMeasuredDimension(width, height);
}