所以我有一个问题，每当我使用得到的克隆 url
从git克隆离子源代码时然后使用ionic cordova运行android在visual studio代码中运行代码，我得到以下错误>
C:\Ionic Projects\PPAppHub2\platforms\android\src\com\ionicframework\common\IonicCordovaCommon.java:72: error: strings in switch are not supported in -source 1.6
switch(action) {
^
(use -source 7 or higher to enable strings in switch)
C:\Ionic Projects\PPAppHub2\platforms\android\src\com\ionicframework\common\IonicCordovaCommon.java:144: error: cannot find symbol
SharedPreferences prefs = this.cordova.getContext().getSharedPreferences("com.ionic.deploy.preferences", Context.MODE_PRIVATE);
^
symbol: method getContext()
location: variable cordova of type CordovaInterface
C:\Ionic Projects\PPAppHub2\platforms\android\src\com\ionicframework\common\IonicCordovaCommon.java:201: error: cannot find symbol
SharedPreferences prefs = this.cordova.getContext().getSharedPreferences("com.ionic.deploy.preferences", Context.MODE_PRIVATE);
^
symbol: method getContext()
location: variable cordova of type CordovaInterface
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: C:\Ionic Projects\PPAppHub2\platforms\android\src\org\apache\cordova\file\AssetFilesystem.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
3 errors
:compileDebugJavaWithJavac FAILED
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
* Get more help at https://help.gradle.org
27 actionable tasks: 1 executed, 26 up-to-date
BUILD FAILED in 2s
(node:8376) UnhandledPromiseRejectionWarning: Error: cmd: Command failed with exit code 1 Error output:
C:\Ionic Projects\PPAppHub2\platforms\android\src\com\ionicframework\common\IonicCordovaCommon.java:72: error: strings in switch are not supported in -source 1.6
switch(action) {
^
(use -source 7 or higher to enable strings in switch)
C:\Ionic Projects\PPAppHub2\platforms\android\src\com\ionicframework\common\IonicCordovaCommon.java:144: error: cannot find symbol
SharedPreferences prefs = this.cordova.getContext().getSharedPreferences("com.ionic.deploy.preferences", Context.MODE_PRIVATE);
^
symbol: method getContext()
location: variable cordova of type CordovaInterface
C:\Ionic Projects\PPAppHub2\platforms\android\src\com\ionicframework\common\IonicCordovaCommon.java:201: error: cannot find symbol
SharedPreferences prefs = this.cordova.getContext().getSharedPreferences("com.ionic.deploy.preferences", Context.MODE_PRIVATE);
^
symbol: method getContext()
location: variable cordova of type CordovaInterface
Note: Some input files use or override a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: C:\Ionic Projects\PPAppHub2\platforms\android\src\org\apache\cordova\file\AssetFilesystem.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
3 errors
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
* Get more help at https://help.gradle.org
BUILD FAILED in 2s
at ChildProcess.whenDone (C:\Ionic Projects\PPAppHub2\platforms\android\cordova\node_modules\cordova-common\src\superspawn.js:169:23)
at ChildProcess.emit (events.js:160:13)
at maybeClose (internal/child_process.js:943:16)
at Process.ChildProcess._handle.onexit (internal/child_process.js:220:5)
(node:8376) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:8376) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
PS C:\Ionic Projects\PPAppHub2>
我已经尝试运行npm install，将ionic cordova platfrom删除android并使用ionic cordova platform重新添加它，但没有运气添加android。谁能提供一些建议？