您可以创建自定义绘图来动态更改圆的颜色和半径

import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.drawable.Drawable;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;

public class CircleDrawable extends Drawable {

    private Paint circlePaint;
    private int fillColor;
    private int strokeColor;
    private float radius;

    public CircleDrawable(int fillColor, int strokeColor, float radius) {
        this.fillColor = fillColor;
        this.strokeColor = strokeColor;
        this.radius = radius;
        circlePaint=new Paint(Paint.ANTI_ALIAS_FLAG);
    }

    @Override
    public void draw(@NonNull Canvas canvas) {
        int x=getBounds().centerX();
        int y=getBounds().centerY();
        //draw fill color circle
        circlePaint.setStyle(Paint.Style.FILL);
        circlePaint.setColor(fillColor);
        canvas.drawCircle(x,y,radius,circlePaint);
        // draw stroke circle
        circlePaint.setStyle(Paint.Style.STROKE);
        circlePaint.setColor(strokeColor);
        circlePaint.setStrokeWidth(5);
        canvas.drawCircle(x,y,radius,circlePaint);
    }

    @Override
    public void setAlpha(int alpha) {
        circlePaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(@Nullable ColorFilter colorFilter) {
         circlePaint.setColorFilter(colorFilter);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}

从UI设置此项以获得圆形

imageView.setImageDrawable(new CircleDrawable(Color.RED,Color.YELLOW,100));

输出将是这样的

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>

如果你想要这样的圆圈

尝试使用以下代码：

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:innerRadius="0dp"
    android:shape="ring"
    android:thicknessRatio="2"
    android:useLevel="false" >
    <solid android:color="@android:color/white" />
    <stroke
        android:width="1dp"
        android:color="@android:color/darker_gray" />
</shape>

Android XML可绘制文件中的圆形

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="@android:color/white" />
    <stroke
        android:width="1.5dp"
        android:color="@android:color/holo_red_light" />
    <size
        android:width="120dp"
        android:height="120dp" />
</shape>

截图

你可以试试这个-

<?xml version="1.0" encoding="utf-8"?>
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="ring"
    android:innerRadiusRatio="700"
    android:thickness="100dp"
    android:useLevel="false">

    <solid android:color="#CCC" />

</shape>

此外，您可以通过调整android：厚度来调整圆的半径。

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

    <!-- fill color -->
    <solid android:color="@color/white" />

    <!-- radius -->
    <stroke
        android:width="1dp"
        android:color="@color/white" />

    <!-- corners -->
    <corners
        android:radius="2dp"/>
</shape>