React-Native ERROR: JAVA_HOME is not set and no ‘java’ command could be found in your PATH.

ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.

Please set the JAVA_HOME variable in your environment to match the
location of your Java installation.
error Could not install the app on the device, read the error above for details.
Make sure you have an Android emulator running or a device connected and have
set up your Android development environment:
https://facebook.github.io/react-native/docs/getting-started.html
error Command failed: gradlew.bat app:installDebug. Run CLI with --verbose flag for more details.
运行react-native时候出现这个问题，

先检查是否已安装java jdk

并以配置好环境变量

git下载

配置环境变量

以win10为例

桌面》电脑》右击属性》高级系统设置》环境变量》系统变量

点击新建

变量名：JAVA_HOME

路径：根据自己安装目录

编辑path那个变量

添加编辑==%JAVA_HOME%\bin==
重新打开cmd窗口

项目文件目录下 运行react-native run-android