Flutter installation is a sdkmanager problem - Codes Helper

download flutter
in the first step, decompress it in the second step, and add the environment variable% flutter%/bin
third, no problem

-sharp flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[] Flutter (Channel stable, v1.0.0, on Microsoft Windows [Version 10.0.10240], locale zh-CN)
[!] Android toolchain - develop for Android devices (Android SDK 28.0.3)
    X Android license status unknown.
[] Android Studio (version 3.3)
[!] IntelliJ IDEA Ultimate Edition (version 2017.3)
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
[] VS Code (version 1.31.1)
[!] Connected device
    ! No devices available

! Doctor found issues in 3 categories.

here is a

Android toolchain - develop for Android devices (Android SDK 28.0.3)
    X Android license status unknown.

question

I enter

-sharpflutter doctor --android-licenses
-sharp Y/N
A newer version of the Android SDK is required. To update, run:
C:\Users\varjay\AppData\Local\Android\Sdk\tools\bin\sdkmanager --update

I am prompted to enter

C:\Users\varjay\AppData\Local\Android\Sdk\tools\bin\sdkmanager --update

but

Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema
        at com.android.repository.api.SchemaModule$SchemaModuleVersion.<init>(SchemaModule.java:156)
        at com.android.repository.api.SchemaModule.<init>(SchemaModule.java:75)
        at com.android.sdklib.repository.AndroidSdkHandler.<clinit>(AndroidSdkHandler.java:81)
        at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:73)
        at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:48)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.annotation.XmlSchema
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:185)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:496)

I had an Android environment before

javac 9.0.1

java version "1.8.0mm 201"
Java (TM) SE Runtime Environment (build 1.8.0_201-b09)
Java HotSpot (TM) 64-Bit Server VM (build 25.201-b09, mixed mode)