刚刚有这个错误，通过在Android Studio上下载Android SDK命令行工具(最新)，在首选项>外观和行为>系统设置> Android SDK > SDK工具并重新运行flutter doctor——Android -licenses来解决

最后，将新工具添加到你的PATH中，在你的.bashrc， .zshrc或类似的目录中，在过时的工具之前:

export PATH=$PATH:$ANDROID_HOME/cmdline-tools/latest/bin

当使用Linux时，一个简单的选项是安装JDK版本8，然后选择它作为默认使用:

sudo update-alternatives --config java

奇怪的是，Java9与android-sdk不兼容

$ avdmanager
Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema
    at com.android.repository.api.SchemaModule$SchemaModuleVersion.<init>(SchemaModule.java:156)
    at com.android.repository.api.SchemaModule.<init>(SchemaModule.java:75)
    at com.android.sdklib.repository.AndroidSdkHandler.<clinit>(AndroidSdkHandler.java:81)
    at com.android.sdklib.tool.AvdManagerCli.run(AvdManagerCli.java:213)
    at com.android.sdklib.tool.AvdManagerCli.main(AvdManagerCli.java:200)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.annotation.XmlSchema
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:582)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:185)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:496)
    ... 5 more

将所有命令合并为一个命令，以便于参考:

$ sudo rm -fr /Library/Java/JavaVirtualMachines/jdk-9*.jdk/
$ sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin
$ sudo rm -fr /Library/PreferencePanes/JavaControlPanel.prefPane

$ /usr/libexec/java_home -V
Unable to find any JVMs matching version "(null)".
Matching Java Virtual Machines (0):
Default Java Virtual Machines (0):
No Java runtime present, try --request to install

$ brew tap caskroom/versions
$ brew cask install java8
$ touch ~/.android/repositories.cfg
$ brew cask install android-sdk
$ echo 'export ANDROID_SDK_ROOT="/usr/local/share/android-sdk"' >> ~/.bash_profile
$ java -version
java version "1.8.0_162"
Java(TM) SE Runtime Environment (build 1.8.0_162-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.162-b12, mixed mode)
$ avdmanager

Usage:
      avdmanager [global options] [action] [action options]
      Global options:
  -s --silent     : Silent mode, shows errors only.
  -v --verbose    : Verbose mode, shows errors, warnings and all messages.
     --clear-cache: Clear the SDK Manager repository manifest cache.
  -h --help       : Help on a specific command.

Valid actions are composed of a verb and an optional direct object:
-   list              : Lists existing targets or virtual devices.
-   list avd          : Lists existing Android Virtual Devices.
-   list target       : Lists existing targets.
-   list device       : Lists existing devices.
- create avd          : Creates a new Android Virtual Device.
-   move avd          : Moves or renames an Android Virtual Device.
- delete avd          : Deletes an Android Virtual Device.

我的Java版本是15.0.1。适用于Mac操作系统。

这就是我解决问题的方法。

下载zip: jaf- 31_1 .zip从:https://download.oracle.com/otn-pub/java/jaf/1.1.1/jaf-1_1_1.zip?AuthParam=1609860571_68ca6f30491c76e81970a3849504fb6a 从https://download.oracle.com/otn-pub/java/jaf/1.1.1/jaf-1_1_1.zip?AuthParam=1609860571_68ca6f30491c76e81970a3849504fb6a下载了zip: jaxb-ri-2.3.1.zip 解压缩到一个文件夹:~/jars/。导出的类路径如下

export  
 CLASSPATH=~/jars/FastInfoset.jar:~/jars/activation.jar:~/jars/codemodel.jar:~/jars/dtd-parser.jar:~/jars/istack-commons-runtime.jar:~/jars/istack-commons-tools.jar:~/jars/jaf-1.1.1:~/jars/jaf-1_1_1.zip:~/jars/javax.activation-api.jar:~/jars/jaxb-api.jar:~/jars/jaxb-jxc.jar:~/jars/jaxb-ri:~/jars/jaxb-ri-2.3.1.zip:~/jars/jaxb-runtime.jar:~/jars/jaxb-xjc.jar:~/jars/relaxng-datatype.jar:~/jars/rngom.jar:~/jars/stax-ex.jar:~/jars/txw2.jar:~/jars/xsom.jar

cd ~/Library/Android/sdk/tools/bin/sdkmanager修改CLASSPATH如下所示

类路径=$CLASSPATH：$APP...

保存文件后重新执行命令。

最好的方法是使用下面的命令

   $ wget https://dl.google.com/android/repository/platform-tools-latest-linux.zip
   $ unzip \platform-tools-latest-linux.zip
   $ sudo cp platform-tools/adb /usr/bin/adb
   $ sudo cp platform-tools/fastboot /usr/bin/fastboot

现在运行adb版本来验证它是否已经更新。

更新了我当前的Android SDK，一切都很顺利。