Pfthb

Two ways this can be done, first one in style.xml and second in code:

1. Add as below in style.xml, alter the value(currently 90%) to meet your needs.

<style name="Theme_Dialog" parent="android:Theme.Holo.Dialog">
 <item name="android:windowMinWidthMajor">90%</item>
 <item name="android:windowMinWidthMinor">90%</item>
</style>

2. Add setlayout to match_parent

 final Dialog contacts_dialog = new Dialog(ActivityGroup.this,
 R.style.theme_sms_receive_dialog);
 contacts_dialog.setContentView(R.layout.dialog_schedule_date_time);

getWindow().setLayout(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.MATCH_PARENT);

 contacts_dialog.setCancelable(true);
 contacts_dialog.setCanceledOnTouchOutside(true);
 contacts_dialog.show();

You need to get the current Window and set it's LayoutParams like so:

Dialog d=new Dialog(mContext,R.style.mydialog);
.........
.........
myDialog.show();
Window window = myDialog.getWindow();
window.setLayout(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

Alternative(if above solution does't works)

In case above code not works well you can use a workaround

styles.xml

<style name="mydialog"></style>

Java

Dialog d=new Dialog(mContext,R.style.mydialog);
.........
.........
myDialog.show();
Window window = myDialog.getWindow();
window.setLayout(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

For full width dialog you can create custom style for dialog. Code is given below for full width dialog:

<style name="Custom_Dialog" parent="ThemeOverlay.AppCompat.Light" >
 <item name="windowMinWidthMajor">100%</item>
 <item name="windowMinWidthMinor">65%</item>
</style>

To assign this style to the dialog's constructor, add this to onCreate() method right after setContentView():

getWindow()
 .setLayout(
 ViewGroup.LayoutParams.FILL_PARENT,
 ViewGroup.LayoutParams.WRAP_CONTENT
 );

In my case width of custom dialog shrinks in size(width) as the content inside dialog becomes smaller in width even though the the width property was set

android:layout_width="match_parent"

I just fixed that width to screen size and now its working according to my requirement

android:layout_width="320dp"

In case anyone is wondering how to do it for a dialog shown using DialogFragment, you can override onCreateDialog to return a Dialog with custom style that has windowMinWidthMajor and minor set to 90%

@NonNull
@Override
public Dialog onCreateDialog(Bundle savedInstanceState) 
 return new Dialog(getActivity(), R.style.WideDialog);

Style:

<style name="WideDialog" parent="Base.Theme.AppCompat.Dialog">
 <item name="android:windowMinWidthMajor">90%</item>
 <item name="android:windowMinWidthMinor">90%</item>
</style>

Add code when you want to open dialog

 final Dialog mBottomSheetDialog = new Dialog(getActivity(), R.style.MaterialDialogSheet);

 mBottomSheetDialog.setContentView(R.layout.dialog_mainscreen_filter); // your custom view.
 mBottomSheetDialog.setCancelable(true);
 mBottomSheetDialog.getWindow().setLayout(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
 mBottomSheetDialog.getWindow().setGravity(Gravity.BOTTOM);
 mBottomSheetDialog.show();


 ImageView img_cross = mBottomSheetDialog.findViewById(R.id.img_cross);
 final ImageView img_new = mBottomSheetDialog.findViewById(R.id.img_new);
 final ImageView img_Used = mBottomSheetDialog.findViewById(R.id.img_Used);


 img_cross.setOnClickListener(new View.OnClickListener() 
 @Override
 public void onClick(View view) 
 mBottomSheetDialog.dismiss();
 
 );


 img_new.setOnClickListener(new View.OnClickListener() 
 @Override
 public void onClick(View view) 
 img_new.setImageResource(R.drawable.checkbox_tick);
 img_Used.setImageResource(R.drawable.checkbox_tick_gray);
 
 );
 img_Used.setOnClickListener(new View.OnClickListener() 
 @Override
 public void onClick(View view) 
 img_Used.setImageResource(R.drawable.checkbox_tick);
 img_new.setImageResource(R.drawable.checkbox_tick_gray);
 
 );

dialog's xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 >


 <android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 app:cardBackgroundColor="@color/colorWhite"
 app:cardCornerRadius="5dp"
 app:cardElevation="@dimen/margin_10">

 <LinearLayout xmlns:app="http://schemas.android.com/apk/res-auto"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:orientation="vertical"
 android:padding="@dimen/margin_10">

 <RelativeLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerVertical="true"
 android:text="@string/filter"
 android:textStyle="bold"
 android:textColor="@color/colorGreen"
 android:textSize="@dimen/font_large" />

 <ImageView
 android:id="@+id/img_cross"
 android:layout_width="25dp"
 android:layout_height="25dp"
 android:layout_alignParentRight="true"
 android:layout_centerVertical="true"
 android:src="@drawable/cross" />
 </RelativeLayout>

 <View
 android:layout_width="match_parent"
 android:layout_height="1dp"
 android:layout_marginTop="@dimen/margin_20"
 android:background="@color/colorfaintGreen" />

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_marginTop="@dimen/margin_20"
 android:gravity="center_vertical"
 android:orientation="horizontal">

 <ImageView
 android:id="@+id/img_new"
 android:layout_width="25dp"
 android:layout_height="25dp"
 android:src="@drawable/checkbox_tick" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_marginLeft="@dimen/margin_10"
 android:text="@string/New"
 android:textColor="@color/colorText"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />

 <ImageView
 android:id="@+id/img_Used"
 android:layout_width="25dp"
 android:layout_height="25dp"
 android:layout_marginLeft="@dimen/margin_30"
 android:src="@drawable/checkbox_tick_gray" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_marginLeft="@dimen/margin_10"
 android:text="@string/Used"
 android:textColor="@color/colorText"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />

 </LinearLayout>

 <View
 android:layout_width="match_parent"
 android:layout_height="1dp"
 android:layout_marginTop="@dimen/margin_20"
 android:background="@color/colorfaintGreen" />

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_marginTop="@dimen/margin_20"
 android:orientation="horizontal">

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:orientation="vertical">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="00"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_medium"
 android:textStyle="bold" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="|"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />
 </LinearLayout>

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:orientation="vertical">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="50"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_medium"
 android:textStyle="bold" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="|"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />
 </LinearLayout>

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:orientation="vertical">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="100"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_medium"
 android:textStyle="bold" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="|"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />
 </LinearLayout>

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:orientation="vertical">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="200"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_medium"
 android:textStyle="bold" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="|"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />
 </LinearLayout>

 <LinearLayout
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_weight="1"
 android:gravity="center"
 android:orientation="vertical">

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="200+"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_medium"
 android:textStyle="bold" />

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:text="|"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />
 </LinearLayout>


 </LinearLayout>

 <RelativeLayout
 android:layout_width="wrap_content"
 android:layout_height="wrap_content">

 <ImageView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_centerVertical="true"
 android:layout_marginLeft="22dp"
 android:layout_marginTop="@dimen/margin_20"
 android:src="@drawable/filled_green" />

 <SeekBar
 android:id="@+id/seekbar"
 style="@style/SeekBarWithoutSteps"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:layout_marginLeft="22dp"
 android:layout_marginRight="22dp"
 android:layout_marginTop="@dimen/margin_10"
 android:max="4"
 android:maxHeight="@dimen/margin_5"
 android:minHeight="@dimen/margin_5"
 android:paddingLeft="@dimen/margin_10"
 android:paddingRight="@dimen/margin_10"
 android:progressBackgroundTint="@color/colorGray"
 android:progressTint="@color/colorGreen"
 android:theme="@style/Widget.AppCompat.SeekBar.Discrete"
 android:thumb="@drawable/filled_green"
 android:thumbOffset="15dp" />


 </RelativeLayout>

 <TextView
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_gravity="center_horizontal"
 android:text="@string/search_near_me_in_km"
 android:textColor="@color/colorTextGray"
 android:textSize="@dimen/fontsize_normal"
 android:textStyle="bold" />


 <Button
 android:id="@+id/btn_register"
 android:layout_width="match_parent"
 android:layout_height="@dimen/btn_height"
 android:layout_marginBottom="@dimen/margin_10"
 android:layout_marginTop="@dimen/margin_10"
 android:background="@drawable/btn_bg_green_rounded"
 android:text="@string/submit"
 android:textColor="@color/colorWhite"
 android:textSize="@dimen/fontsize_medium" />

 </LinearLayout>


 </android.support.v7.widget.CardView>
</LinearLayout>

Style.xml
------------------------------------------

 <style name="MaterialDialogSheet" parent="@android:style/Theme.Dialog">
 <item name="android:windowIsTranslucent">true</item>
 <item name="android:windowBackground">@android:color/white</item>
 <item name="android:windowContentOverlay">@null</item>
 <item name="android:windowNoTitle">true</item>
 <item name="android:backgroundDimEnabled">true</item>
 <item name="android:windowIsFloating">false</item>
 <item name="android:windowAnimationStyle">@style/MaterialDialogSheetAnimation</item>
 </style>


 <style name="MaterialDialogSheetAnimation">
 <item name="android:windowEnterAnimation">@anim/popup_show</item>
 <item name="android:windowExitAnimation">@anim/popup_hide</item>
 </style>

Add Animations in res folder:
anim/popup_show.xml

 <?xml version="1.0" encoding="utf-8"?>
 <set xmlns:android="http://schemas.android.com/apk/res/android">
 <translate
 android:duration="300"
 android:fromYDelta="100%p"
 android:interpolator="@android:anim/accelerate_decelerate_interpolator"
 android:toYDelta="0" />
 </set>

anim/popup_hide.xml

 <?xml version="1.0" encoding="utf-8"?>
 <set xmlns:android="http://schemas.android.com/apk/res/android">
 <translate
 android:duration="300"
 android:fromYDelta="0"
 android:interpolator="@android:anim/accelerate_decelerate_interpolator"
 android:toYDelta="100%p" />
 </set>

This answer could be helpful for you.
Android dialog width

@Override public void onStart() 
 super.onStart();
 Dialog dialog = getDialog();
 if (dialog != null) 
 dialog.getWindow()
 .setLayout((int) (getScreenWidth(getActivity()) * .9), (int)(getScreenHeight(getActivity()) * .6) );
 


public static int getScreenWidth(Activity activity) 
 Point size = new Point();
 activity.getWindowManager().getDefaultDisplay().getSize(size);
 return size.x;


public static int getScreenHeight(Activity activity) 
 Point size = new Point();
 activity.getWindowManager().getDefaultDisplay().getSize(size);
 return size.y;

example of 90% width and 60% height

MyDialogFragment myDialogFragment = 
 new MyDialogFragment(activity,arraylist.get(position).getImage());
 myDialogFragment.show();

Window window = myDialogFragment.getWindow();
 window.setLayout(WindowManager.LayoutParams.MATCH_PARENT, WindowManager.LayoutParams.MATCH_PARENT);