由于某种原因，我无法在ConstraintLayout中画一个圆圈，我只是无法使用上面的任何答案。

当你按下“Alt+7”时，一个简单的文本视图显示了文本，效果很好：

 <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#0075bc"
            android:textSize="40dp"
            android:text="•"></TextView>

尝试以下带破折号的代码：

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval">
<size
    android:width="@dimen/_60sdp"
    android:height="@dimen/_60sdp" />

<solid android:color="@color/black" />

<stroke
    android:width="@dimen/_1sdp"
    android:color="@color/white"
    android:dashWidth="@dimen/_1sdp"
    android:dashGap="@dimen/_1sdp" />

尝试不带破折号的代码：

<?xml version="1.0" encoding="utf-8"?><shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="oval">

<size
    android:width="@dimen/_60sdp"
    android:height="@dimen/_60sdp" />

<solid android:color="@color/black" />

<stroke
    android:width="@dimen/_1sdp"
    android:color="@color/white" />

您可以按如下方式使用VectorDrawable：

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="200dp"
    android:height="200dp"
    android:viewportHeight="64"
    android:viewportWidth="64">

    <path
        android:fillColor="#ff00ff"
        android:pathData="M22,32
        A10,10 0 1,1 42,32
        A10,10 0 1,1 22,32 Z" />
</vector>

上述xml呈现为：

首先创建可绘制资源文件

然后将此代码添加到文件中

 <?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
       // here define the shape
    android:shape="oval">

   <solid 
        // here define your color
       android:color="#666666"/>

   <size 
        // here define your shape size
       android:width="120dp"
        android:height="120dp"/>
</shape>

只需使用

ShapeDrawable circle = new ShapeDrawable( new  OvalShape() );

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="oval">
            <solid android:color="@color/text_color_green"/>
            <!-- Set the same value for both width and height to get a circular shape -->
            <size android:width="250dp" android:height="250dp"/>
        </shape>
    </item>
</selector>