java - LocationSettingsStates 类在接收位置请求时会做什么？

Question

在文档中here我正在关注如何接收位置请求，并且我注意到这两个代码块中有两个不寻常的事情:

result.setResultCallback(new ResultCallback<LocationSettingsResult>() {
     @Override
     public void onResult(LocationSettingsResult result) {
         final Status status = result.getStatus();
         final LocationSettingsStates = result.getLocationSettingsStates(); //<--This line I don't understand
         switch (status.getStatusCode()) {
             case LocationSettingsStatusCodes.SUCCESS:
                 // All location settings are satisfied. The client can initialize location
                 // requests here.
                 ...
                 break;
             case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:
                 // Location settings are not satisfied. But could be fixed by showing the user
                 // a dialog.
                 try {
                     // Show the dialog by calling startResolutionForResult(),
                     // and check the result in onActivityResult().
                     status.startResolutionForResult(
                         OuterClass.this,
                         REQUEST_CHECK_SETTINGS);
                 } catch (SendIntentException e) {
                     // Ignore the error.
                 }
                 break;
             case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:
                 // Location settings are not satisfied. However, we have no way to fix the
                 // settings so we won't show the dialog.
                 ...
                 break;
         }
     }
 });

在第二个 block 中:

@Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     final LocationSettingsStates states = LocationSettingsStates.fromIntent(intent);  //<--And this line
     switch (requestCode) {
         case REQUEST_CHECK_SETTINGS:
             switch (resultCode) {
                 case Activity.RESULT_OK:
                     // All required changes were successfully made
                     ...
                     break;
                 case Activity.RESULT_CANCELED:
                     // The user was asked to change settings, but chose not to
                     ...
                     break;
                 default:
                     break;
             }
             break;
     }
 }

我添加了一些箭头指向我不理解的行。特别是这两个:

最终 LocationSettingsStates = result.getLocationSettingsStates();

final LocationSettingsStates states = LocationSettingsStates.fromIntent(intent);

第一行是我以前从未见过的。将值分配给数据类型如何有效？那么该类在该代码块的其他任何地方都不再使用，那么赋值的目的是什么？

在另一行中，现在它正在为该数据类型的名为 states 的实例分配一个值，但该实例未在 onActivityResult() 中的其他任何地方使用。

那么这是怎么回事呢？谢谢。

Answer 1

第一行肯定是一个拼写错误；它应该是这样的:

final LocationSettingsStates states = result.getLocationSettingsStates();

是的，这两个地方都没有使用它，这很奇怪，但你可以调用 things就像 isBleUsable() 一样，以确定现在到底存在和可用的内容。在后一种情况下，它是尝试解决后可用的内容。