Android 如何通过一个方法更新整个kotlin类中的变量，然后通过另一个方法调用检索更新的变量

我编写了一个kotlin类，其中包含一个被覆盖的乐趣，以及将var更新到类作用域中的乐趣（不幸的是，我对kotlin还不熟悉！）

在我调用方法的地方，我会：

myObject.updateMyVar("new string")
myObject.sample()

我想知道如何更新我需要的var，因为我无法在“fun sample”中添加新的参数，因为它覆盖了一个类方法

提前感谢，向大家致以最良好的问候：）

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更新：添加我的实际代码，因为在我调用overrid方法时，类似乎无法保持正确的更新值：

这是我的BroadcastReceiver，用于检查下载何时完成，以及它们是否执行某些操作

class DownloadBroadcastManager: BroadcastReceiver() {

    var myClassFilename:String = "default"
    var myClassExtension:String = ".default"

    override fun onReceive(context: Context, intent: Intent) {
        val action = intent.action

        if (DownloadManager.ACTION_DOWNLOAD_COMPLETE == action) {
            //Show a notification
            // here there's a log to check if var are updated
            println("myTag - variables $myClassFilename, $myClassExtension")

            Toast.makeText(context, "Download of $myClassFilename$myClassExtension completed", Toast.LENGTH_LONG).show()
            // richiama azioni come player o display image o altro?

            //player
            var uri = Uri.parse (Environment.getExternalStorageDirectory().getPath() + "/Download/$myClassFilename$myClassExtension") //myClassExtension is ".mp3", dot is included, however it seems class is re-intialized as i call the method
            println("myTag - uri: $uri")
            println("myTag - context: $context")

            var mPlayer = MediaPlayer() // I added this declaration (that's be re-done later) cause I had a problem in making the player running (of course giving it a valid path to a valid file). Now this is "junk code"
            mPlayer.stop()
            mPlayer.reset()
            mPlayer.release()
            mPlayer = MediaPlayer.create(context, uri) // here there's the proper declaration + initialization
            mPlayer.start()

        }
    }
}

这是我的下载课上的部分

var brReceiver = DownloadBroadcastManager()
    // shows when download is completed
    println("myTag - ${brReceiver.myClassFilename}, ${brReceiver.myClassExtension}: originals") //here shows the default: it's right
    val intent = Intent(context, MainActivity::class.java)
    brReceiver.myClassFilename = myTitle // inject filename
    brReceiver.myClassExtension = ".mp3" // inject file extension
    println("myTag - ${brReceiver.myClassFilename}, ${brReceiver.myClassExtension}: modified") // here it shows my class property as correctly updated

    brReceiver.onReceive(context, intent) // here, as calling the override fun, it get back to default value of the property

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根据kotlin的文档，您可以为任何变量定义

getter

和

setter

方法，如下所示：

var <propertyName>[: <PropertyType>] [= <property_initializer>]
[<getter>]
[<setter>]

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您只需执行以下操作：

摆脱

updateMyVar

函数：

class MySampleClass: SampleReference(){
    var varToBeUpdated:String = "my string" //var in class scope to be updated

    override fun sample(context: Context, intent: Intent){
        //here i need my varToBeUpdated with new string
        runSomeThing(varToBeUpdated)
        //some work to be done here
    }
}

直接更新

varToBeUpdated

属性：

val myObject = MySampleClass()
myObject.varToBeUpdated = "new string"
myObject.sample()

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更新：

---

如果调用

brReceiver.onReceive（…）

将更新

下载广播管理器中的值。但你不应该那样做。Android框架为您调用它。当它发生时，将创建
DownloadBroadcastManager
类的新实例，并设置默认值。我们使用intent将数据传递给
BroadcastReceiver
，例如在创建
BroadcastReceiver
时调用
intent.putExtra（“文件名”、“您的文件名”）
，并在
onReceive（）
函数中调用
intent.getStringExtra（“文件名”）
以获取值
 好的，首先感谢萨米亚扎尔先生，特别是谢尔盖，感谢他们的回答和难以置信的耐心！
不幸的是，当框架重新初始化时，BroadcastReceiver似乎也会丢失我之前在Intent变量中添加的任何额外内容。
我最终解决了这个问题，让我检索所需的字符串，只需将一行文本写入内部存储器中的文件，然后在BroadcastReceiver类中检索它。
代码如下：

这是我在BroadcastReceiver类中的“onReceive”方法

 override fun onReceive(context: Context, intent: Intent) {
    val action = intent.action
    Log.i("Receiver", "myTag - Broadcast received: " + action)
    var myFilename = "deafult"

    if (DownloadManager.ACTION_DOWNLOAD_COMPLETE == action) {

        // read the previously created file from internal storage
        var fileInputStream: FileInputStream? = null
        fileInputStream = context.openFileInput("storeDownloadedData")
        var inputStreamReader: InputStreamReader = InputStreamReader(fileInputStream)
        val bufferedReader: BufferedReader = BufferedReader(inputStreamReader)

        // here setting string var and stringbuilder var to catch the text updated outside the while loop
        val stringBuilder: StringBuilder = StringBuilder()
        var text: String? = null
        var sumText:java.lang.StringBuilder? = null
        // while loop for reading the file line by line (in this case the file can contains just one line a time)
        while ({ text = bufferedReader.readLine(); text }() != null) {
            sumText = stringBuilder.append(text)
        }

        // convert stringBuilder to a list of string splitting the original string obtained by file reading
        var secondText:String = "default"
        println("myTag - text: $text, $sumText")
        if (sumText != null){
            secondText = sumText.toString()
            var listFromText = secondText.split(",")
            // set filename to the title contained in the string
            myFilename = listFromText[0]
        }

        //player - finally play the file retrieving the title from the file in internal storage
        var uri = Uri.parse (Environment.getExternalStorageDirectory().getPath() + "/Download/$myFilename.mp3")
        println("myTag - uri: $uri")
        println("myTag - context: $context")

        var mPlayer = MediaPlayer.create(context, uri)
        mPlayer.start()

    }

这是在我的DownloadManager类中添加的代码：

// strore into an internal storage file the data of title and extensione for the file's gonna be downloaded
    val myStoredFile:String = "storeDownloadedData"
    val data:String = "$myTitle,.mp3"
    val fileOutputStream: FileOutputStream
    // write file in internal storage
    try {
        fileOutputStream = context.openFileOutput(myStoredFile, Context.MODE_PRIVATE)
        fileOutputStream.write(data.toByteArray())
    }catch (e: Exception){
        e.printStackTrace()
    }

    // it notifies when download is completed
    val intent = Intent(context, MainActivity::class.java)
    var brReceiver = DownloadBroadcastManager()

我不知道这是否是“ortodox”，但它似乎能工作
：）
如果您将
varToBeUpdated
公开，您可以使用
myObject.varToBeUpdated=“my string”
访问它，也许我现在的问题是我没有公开它？嗯：没什么可做的。当我调用该方法时，有什么东西再次声明了我的var，或者有什么东西阻止了我更新它们
var mPlayer=MediaPlayer（）//我添加了这个声明（稍后会重新执行），因为我在使播放器运行时遇到了问题（当然是给它一个有效文件的有效路径）。现在这是“垃圾代码”
您可能应该删除它。如果您调用
brReceiver.onReceive（…）
下载广播管理器中的值将更新。但你不应该那样做。Android框架为您调用它。当它发生时，将创建
DownloadBroadcastManager
类的新实例，并设置默认值。我们使用意图将数据传递给BroadcastReceiver，例如，在创建BroadcastReceiver时调用
intent.putExtra（“文件名”、“您的文件名”）
，并在
onReceive（）函数中调用
intent.getStringExtra（“文件名”）
。真的非常感谢！我认为这个解决方案违反了封装原则。不，它没有。科特林有财产的概念。要使用属性，我们只需按名称引用它
varToBeUpdated
是一个属性。getter和setter是可选的。我现在只能在pc上工作。。似乎有什么东西阻止了这一切。该对象是否可以重新初始化，但我没有注意到？您可以在Android Studio中进行检查，通过右键单击底部窗口的属性->查找用法->查找
值写入
下拉列表来更新该值。当您单击它时，您将获得更新属性的所有位置。好的，我尝试使用println（）查找用法，并将一些输出发送到控制台。我的结果是，在MainActivity中，更新得到确认：println（myObject.varToBeUpdated）//resutl这里是默认的myObject.varToBeUpdated=“new string”//新的值注入println（myObject.varToBeUpdated）//控制台中的结果这里是新的！myObject.sample（）//在这里它使用默认值再次工作。。。这是怎么回事？提前感谢，向brReceiver.onReceive致意（上下文、意图）
 override fun onReceive(context: Context, intent: Intent) {
    val action = intent.action
    Log.i("Receiver", "myTag - Broadcast received: " + action)
    var myFilename = "deafult"

    if (DownloadManager.ACTION_DOWNLOAD_COMPLETE == action) {

        // read the previously created file from internal storage
        var fileInputStream: FileInputStream? = null
        fileInputStream = context.openFileInput("storeDownloadedData")
        var inputStreamReader: InputStreamReader = InputStreamReader(fileInputStream)
        val bufferedReader: BufferedReader = BufferedReader(inputStreamReader)

        // here setting string var and stringbuilder var to catch the text updated outside the while loop
        val stringBuilder: StringBuilder = StringBuilder()
        var text: String? = null
        var sumText:java.lang.StringBuilder? = null
        // while loop for reading the file line by line (in this case the file can contains just one line a time)
        while ({ text = bufferedReader.readLine(); text }() != null) {
            sumText = stringBuilder.append(text)
        }

        // convert stringBuilder to a list of string splitting the original string obtained by file reading
        var secondText:String = "default"
        println("myTag - text: $text, $sumText")
        if (sumText != null){
            secondText = sumText.toString()
            var listFromText = secondText.split(",")
            // set filename to the title contained in the string
            myFilename = listFromText[0]
        }

        //player - finally play the file retrieving the title from the file in internal storage
        var uri = Uri.parse (Environment.getExternalStorageDirectory().getPath() + "/Download/$myFilename.mp3")
        println("myTag - uri: $uri")
        println("myTag - context: $context")

        var mPlayer = MediaPlayer.create(context, uri)
        mPlayer.start()

    }

// strore into an internal storage file the data of title and extensione for the file's gonna be downloaded
    val myStoredFile:String = "storeDownloadedData"
    val data:String = "$myTitle,.mp3"
    val fileOutputStream: FileOutputStream
    // write file in internal storage
    try {
        fileOutputStream = context.openFileOutput(myStoredFile, Context.MODE_PRIVATE)
        fileOutputStream.write(data.toByteArray())
    }catch (e: Exception){
        e.printStackTrace()
    }

    // it notifies when download is completed
    val intent = Intent(context, MainActivity::class.java)
    var brReceiver = DownloadBroadcastManager()