Question

我在应用程序中进行了两个活动，我希望在我上次中断的地方打开该应用程序。换句话说，不是默认活动，而是上次退出应用程序时的活动。

Answer 1

您可以设置一个SplashActivity，在您的应用程序启动的地方，它将启动其他活动。

在此SplashActivity中，您可以设置var lastActivity，这将是用于保留您上一次活动的代码。您可以通过SharedPreference来获取它，然后转到该活动。

即：

String lastActivity = SharedPreference.getString(...) // I don't really remember the syntax
if (lastActivity == "HelloWorldActivity")
    startActivity(HelloWorldActivity.getStartIntent(context))
else if (lastActivity == "GoodByeActivity")
    startActivity(GoodByeActivity.getStartIntent(context))

然后，别忘了每次更改活动时都编辑您的SharedPreference值。

我不知道这是否是一个好习惯，但请随时进行测试并提出您的想法。

编辑

首先，您需要了解共享首选项文件的方式。我认为它是这样的：

"app_name"="Your app name"
"last_activity"="Your last activity"
"user_age"="23"

这可能是您启动的第一个活动：

class SplashActivity : AppCompatActivity() {

    var lastActivity = ""

    override fun onCreate(savedInstanceState : Bundle?) {
        super.onCreate()

        /*
            Here, we will get the SharedPreferencesFile.
            Then, we get the value linked to the key TAG_LAST_ACTIVITY (set in companion object)
        */
        val sharedPref = this.getSharedPreferences(getString(R.string.shared_preference_file_name), 0)
        lastActivity = sharedPref.getString(TAG_LAST_ACTIVITY, "")

        var activityToStart : AppCompatActivity? = null
        if (lastActivity.isBlank())
             activityToStart = YourActivityToStartAtFirstLaunch.getStartIntent(this)
        else if (lastActivity.equals(TAG_ACTIVITY_ONE))
             activityToStart = ActivityOne.getStartIntent(this)
        else if (lastActivity.equals(TAG_ACTIVITY_TWO))
             activityToStart = ActivityTwo.getStartIntent(this)
        else if
             ... // Use as many as else if you need, but think about the "when" condition, it is better !

        startActivity(activityToStart)
    }

    companion object {
        private const val TAG_LAST_ACTIVITY = "last_activity"
        private const val TAG_ACTIVITY_ONE = "activity_one"
        private const val TAG_ACTIVITY_TWO = "activity_two"
    }
}

这可能是您的ActivityOne，例如：

class ActivityOne : AppCompatActivity() {

    override fun onCreate(savedInstanceState : Bundle?) {
        super.onCreate()

        /*
            Here, we will modify the variable LAST_ACTIVITY in the shared preferences file by setting it to "activity_one".
            So, if the user quit this app now, you will know at next launch in which activity he stopped.
            I think it is a better practice to set this in the onPause() or onStopped() method. Think about it ! ;)
        */
        val sharedPrefEditor = this.getSharedPreferences(getString(R.string.shared_preference_file_name, 0)).edit()
        sharedPrefEditor.putString(TAG_LAST_ACTIVITY, TAG_ACTIVITY_ONE)
        sharedPrefEditor.apply()
    }

    companion object {
        fun getStartIntent(context : Context) : Intent = Intent(context, ActivityOne()::class.java)

        private const val TAG_ACTIVITY_ONE = "activity_one"
        private const val TAG_LAST_ACTIVITY = "last_activity"
    }    
}

不要忘记将共享的首选项文件名放在values / strings.xml文件中：

<string name="shared_preference_file_name">com.example.yourappname.sharedpref"</string>

Kotlin-如何设置共享首选项代码，以便我打开已关闭的应用程序，它会打开上一个活动（我将其留在此处）

1 个答案: