实际90%计算解:

@Override public void onStart() {
   Dialog dialog = getDialog();
   if (dialog != null) {
     dialog.getWindow()
        .setLayout((int) (getScreenWidth(getActivity()) * .9), ViewGroup.LayoutParams.MATCH_PARENT);
   }
}

其中getScreenWidth(Activity Activity)定义如下(最好放在Utils类中):

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

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;
        }
    }

根据Android平台开发人员Dianne Hackborn在这个讨论组的帖子，对话框将窗口的顶层布局宽度和高度设置为WRAP_CONTENT。要使对话框更大，可以将这些参数设置为MATCH_PARENT。

演示代码:

    AlertDialog.Builder adb = new AlertDialog.Builder(this);
    Dialog d = adb.setView(new View(this)).create();
    // (That new View is just there to have something inside the dialog that can grow big enough to cover the whole screen.)

    WindowManager.LayoutParams lp = new WindowManager.LayoutParams();
    lp.copyFrom(d.getWindow().getAttributes());
    lp.width = WindowManager.LayoutParams.MATCH_PARENT;
    lp.height = WindowManager.LayoutParams.MATCH_PARENT;
    d.show();
    d.getWindow().setAttributes(lp);

注意，属性是在对话框显示之后设置的。系统对设置时间很挑剔。(我猜布局引擎必须在对话框第一次显示时设置它们。)

最好通过扩展Theme来实现这一点。对话，那么您就不必玩什么时候调用setAttributes的猜谜游戏了。(尽管让对话框自动采用适当的明暗主题或蜂巢Holo主题需要更多的工作。这可以根据http://developer.android.com/guide/topics/ui/themes.html#SelectATheme来做)

只要给AlertDialog这个主题

<style name="DialogTheme" parent="Theme.MaterialComponents.Light.Dialog.MinWidth">
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="android:windowMinWidthMajor">90%</item>
    <item name="android:windowMinWidthMinor">90%</item>
</style>

在初始化对话框对象并设置内容视图之后。这样做并享受。

(在这种情况下，我设置90%的宽度和70%的高度，因为宽度90%，它将超过工具栏)

DisplayMetrics displaymetrics = new DisplayMetrics();
getActivity().getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int width = (int) ((int)displaymetrics.widthPixels * 0.9);
int height = (int) ((int)displaymetrics.heightPixels * 0.7);
d.getWindow().setLayout(width,height);
d.show();

    final AlertDialog alertDialog;

    LayoutInflater li = LayoutInflater.from(mActivity);
    final View promptsView = li.inflate(R.layout.layout_dialog_select_time, null);

    RecyclerView recyclerViewTime;
    RippleButton buttonDone;

    AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(mActivity);
    alertDialogBuilder.setView(promptsView);

    // create alert dialog
    alertDialog = alertDialogBuilder.create();

    /**
     * setting up window design
     */
    alertDialog.requestWindowFeature(Window.FEATURE_NO_TITLE);


    alertDialog.show();

    DisplayMetrics metrics = new DisplayMetrics(); //get metrics of screen
    mActivity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
    int height = (int) (metrics.heightPixels * 0.9); //set height to 90% of total
    int width = (int) (metrics.widthPixels * 0.9); //set width to 90% of total

    alertDialog.getWindow().setLayout(width, height); //set layout
    recyclerViewTime = promptsView.findViewById(R.id.recyclerViewTime);


    DialogSelectTimeAdapter dialogSelectTimeAdapter = new DialogSelectTimeAdapter(this);
    RecyclerView.LayoutManager linearLayoutManager = new LinearLayoutManager(this);
    recyclerViewTime.setLayoutManager(linearLayoutManager);
    recyclerViewTime.setAdapter(dialogSelectTimeAdapter);

    buttonDone = promptsView.findViewById(R.id.buttonDone);
    buttonDone.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            alertDialog.dismiss();

        }
    });