android - 为什么我的样式没有应用到我的 popupMenu？

Question

根据 How to style PopupMenu?你不能直接设置弹出菜单样式，这似乎与https://developer.android.com/reference/android/widget/PopupWindow.html相反

它声明您可以在 PopupMenu 构造函数中指定样式。根据http://blog.http417.com/2014/06/styling-popupmenu.html看起来我需要指定的属性是“android:popupBackground”和“android:dropDownWidth”。但是，以下只是删除了默认样式，并没有应用我想要的颜色或宽度:

样式.xml:

<style name="popup">
    <item name="android:popupBackground">@color/material_blue_grey_800</item>
    <item name="android:dropDownWidth">350dp</item>
</style>

ActivityA.java

public class ActivityA extends AppCompatActivity implements    
PopupMenu.OnMenuItemClickListener {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_a);
    findViewById(R.id.popupBtn).setOnClickListener(new    
    View.OnClickListener() {
        @Override
        public void onClick(View button) {
            PopupMenu popupMenu = new PopupMenu(ActivityA.this, 
                      button, Gravity.RIGHT, 0, R.style.popup);
        }
    }

@Override
public boolean onMenuItemClick(MenuItem item) {
    return false;
    }
}

activity_a.xml:

<RelativeLayout    xmlns:android="http://schemas.android.com/apk/res/android"
           xmlns:tools="http://schemas.android.com/tools"
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:paddingLeft="@dimen/activity_horizontal_margin"
           android:paddingRight="@dimen/activity_horizontal_margin"
           android:paddingTop="@dimen/activity_vertical_margin"
           android:paddingBottom="@dimen/activity_vertical_margin"
           tools:context=".activities.ActivityA">
  <Button
      android:id="@+id/popupBtn"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_alignParentTop="true"
      android:layout_alignParentRight="true"
      android:text="Press to open menu"/>
</RelativeLayout>

Answer 1

您不能以编程方式应用样式，但可以使用主题来实现:https://developer.android.com/guide/topics/ui/themes.html#ApplyAStyle可以在这里找到类似的答案:https://stackoverflow.com/a/2016344/936269