问题回顾：

在Android8.0手机上不能直接安装Apk，需要权限申请，回调后执行onActivityResult()方法，并弹出对应的dialog，这时需要判断当前Activity是否处于resume状态，通过变量来控制，但结果是这个dialog并不会弹出。

问题本质

Activity跳转到系统应用后回调onActivityResult() 先执行还是onResume()先执行？

查看源码

/**

* Called when an activity you launched exits, giving you the requestCode

* you started it with, the resultCode it returned, and any additional

* data from it. The resultCode will be

* {@link #RESULT_CANCELED} if the activity explicitly returned that,

* didn't return any result, or crashed during its operation.

*

*

You will receive this call immediately before onResume() when your

* activity is re-starting.

*

*

This method is never invoked if your activity sets

* {@link android.R.styleable#AndroidManifestActivity_noHistory noHistory} to

* true.

*

* @param requestCode The integer request code originally supplied to

* startActivityForResult(), allowing you to identify who this

* result came from.

* @param resultCode The integer result code returned by the child activity

* through its setResult().

* @param data An Intent, which can return result data to the caller

* (various data can be attached to Intent "extras").

*

* @see #startActivityForResult

* @see #createPendingResult

* @see #setResult(int)

*/

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

}

onActivityResult()注释中有这么一句话：

You will receive this call immediately before onResume() when your activity is re-starting.

(意思是说当你的Activity重新启动时 onActivityResult() 会在onResume()之前执行)

很显然，如果你的Activity 调用了 startActivityForResult() 方法启动，回调之后会先执行 onActivityResult() ,然后执行onResume()