更简单的是这样做:

int width = (int)(getResources().getDisplayMetrics().widthPixels*0.90);
int height = (int)(getResources().getDisplayMetrics().heightPixels*0.90);

alertDialog.getWindow().setLayout(width, height);

public static WindowManager.LayoutParams setDialogLayoutParams(Activity activity, Dialog dialog)
    {
        try 
        {
            Display display = activity.getWindowManager().getDefaultDisplay();
            Point screenSize = new Point();
            display.getSize(screenSize);
            int width = screenSize.x;

            WindowManager.LayoutParams layoutParams = new WindowManager.LayoutParams();
            layoutParams.copyFrom(dialog.getWindow().getAttributes());
            layoutParams.width = (int) (width - (width * 0.07) ); 
            layoutParams.height = WindowManager.LayoutParams.WRAP_CONTENT;
            return layoutParams;
        } 
        catch (Exception e)
        {
            e.printStackTrace();
            return null;
        }
    }

部分基于阿南德的回答。这对我来说很管用:

override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
    val fragmentActivity = requireActivity()
    val v = View.inflate(context, R.layout.fragment_about_dialog, null)
    val dialog = Dialog(fragmentActivity)
    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE)
    dialog.setContentView(v)

    val wm = fragmentActivity.getSystemService(Context.WINDOW_SERVICE) as WindowManager 

    val display = if (VERSION.SDK_INT >= VERSION_CODES.R) {
        fragmentActivity.display
    } else {
        wm.defaultDisplay // deprecated in API 30
    }

    val size = Point()
    display?.getSize(size)

    val width = size.x - 50
    val height = size.y - 50
    val lp = WindowManager.LayoutParams()
    lp.copyFrom(dialog.window?.attributes)
    lp.width = width
    lp.height = height
    dialog.show()
    dialog.window?.attributes = lp
    
    return dialog
}

对于对话框布局使用constraintLayout:

<androidx.constraintlayout.widget.ConstraintLayout 
        android:id="@+id/dialogLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    ...
</androidx.constraintlayout.widget.ConstraintLayout>

结果:

这在改变屏幕方向时工作得很好。

***In Kotlin You can Code like This : -*** 

fun customDialog(activity: Activity?, layout: Int): Dialog {
    val dialog = Dialog(activity!!)
    try {
        dialog.requestWindowFeature(Window.FEATURE_NO_TITLE)
        dialog.setCancelable(false)
        dialog.setContentView(layout)
        dialog.window!!.setBackgroundDrawable(ColorDrawable(Color.TRANSPARENT))
        dialog.window!!.setLayout(ConstraintLayout.LayoutParams.MATCH_PARENT, ConstraintLayout.LayoutParams.WRAP_CONTENT);
        dialog.show()
    } catch (e: Exception) {

    }
    return dialog
}

下面是我的自定义对话框宽度的变体:

DisplayMetrics displaymetrics = new DisplayMetrics();
mActivity.getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int width = (int) (displaymetrics.widthPixels * (ThemeHelper.isPortrait(mContext) ? 0.95 : 0.65));

WindowManager.LayoutParams params = getWindow().getAttributes();
params.width = width;
getWindow().setAttributes(params);

因此，根据设备方向(ThemeHelper.isPortrait(mContext))对话框的宽度将是95%(纵向模式)或65%(横向模式)。这比作者要求的要多一点，但对某些人来说可能有用。

你需要创建一个从Dialog扩展而来的类，并把这段代码放到你的onCreate(Bundle savedInstanceState)方法中。

对于对话框的高度，代码应该类似于此。

我的答案是基于koma的，但它不需要覆盖onStart，但只需要onCreateView，当你创建新的片段时，默认情况下几乎总是被覆盖。

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.your_fragment_layout, container);

    Rect displayRectangle = new Rect();
    Window window = getDialog().getWindow();
    window.getDecorView().getWindowVisibleDisplayFrame(displayRectangle);

    v.setMinimumWidth((int)(displayRectangle.width() * 0.9f));
    v.setMinimumHeight((int)(displayRectangle.height() * 0.9f));

    return v;
}

我在Android 5.0.1上进行了测试。