public class HorizontalDialog extends Dialog {

    public HorizontalDialog(@NonNull Context context) {
        super(context, R.style.Horizontal_Dialog);
        init();
    }

    public HorizontalDialog(@NonNull Context context, View view) {
        super(context, R.style.Horizontal_Dialog);
        setContentView(view);
        init();
    }

    public HorizontalDialog(@NonNull Context context, View view, @StyleRes int themeResId) {
        super(context, themeResId);
        setContentView(view);
        init();
    }

    private void init() {
        WindowManager windowManager = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);
        Point point = new Point();
        windowManager.getDefaultDisplay().getSize(point);
        WindowManager.LayoutParams params = getWindow().getAttributes();
        params.width = (point.x);
        params.gravity = Gravity.TOP;
        getWindow().setBackgroundDrawableResource(R.color.white);
        getWindow().setAttributes(params);
    }

}

<style name="Horizontal_Dialog" parent="Theme.AppCompat.Light">
        <item name="android:colorBackgroundCacheHint">@null</item>
        <item name="android:colorBackground">?attr/colorBackgroundFloating</item>

        <item name="android:windowFrame">@null</item>
        <item name="android:windowTitleStyle">@style/RtlOverlay.DialogWindowTitle.AppCompat</item>
        <item name="android:windowTitleBackgroundStyle">@style/Base.DialogWindowTitleBackground.AppCompat</item>
        <item name="android:windowBackground">@drawable/abc_dialog_material_background</item>
        <item name="android:windowIsFloating">true</item>
        <item name="android:backgroundDimEnabled">true</item>
        <item name="android:windowContentOverlay">@null</item>
        <item name="android:windowAnimationStyle">@style/Animation.AppCompat.Dialog</item>
        <item name="android:windowSoftInputMode">stateUnspecified|adjustPan</item>

        <item name="windowActionBar">false</item>
        <item name="windowActionModeOverlay">true</item>

        <item name="listPreferredItemPaddingLeft">0dip</item>
        <item name="listPreferredItemPaddingRight">0dip</item>

        <item name="android:listDivider">@null</item>

        <item name="windowFixedWidthMajor">100%</item>
        <item name="windowFixedWidthMinor">100%</item>
        <item name="windowFixedHeightMajor">@null</item>
        <item name="windowFixedHeightMinor">@null</item>
        <item name="android:windowFullscreen">true</item>
        <item name="android:windowNoTitle">true</item>
    </style>