如何返回回调的值答案

【问题标题】：How to return the value off a callback如何返回回调的值
【发布时间】：2020-11-01 19:21:07
【问题描述】：

我正在使用这个：https://github.com/yuriy-budiyev/code-scanner/blob/master/src/main/java/com/budiyev/android/codescanner/DecodeCallback.java

我正在创建一个扫描条形码的应用程序，我希望在扫描条形码后我想将他的价值返回给其他乐趣

我的代码：

var barcodeScanned  = ""
override fun onCreate(savedInstanceState: Bundle?) { 
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    startScanning() 
}

private fun startScanning() {
codeScanner.decodeCallback = DecodeCallback {
            runOnUiThread {
                barcodeScanned = it.text
            }}}

//Here I want to take the barcodeScanned 
private fun callAPI() {
        println("barcode $barcodeScanned") //this is empty
    }

【问题讨论】：

标签： kotlin callback

【解决方案1】：

var barcodeScanned  = ""

override fun onCreate(savedInstanceState: Bundle?) { 
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    startScanning() 
}

private fun startScanning() {
codeScanner.decodeCallback = DecodeCallback {
            runOnUiThread {
                barcodeScanned = it.text
            }}}

//Here I want to take the barcodeScanned 
private fun callAPI() {
        println("barcode $barcodeScanned") 
    }

或者您可以将其作为参数传递

override fun onCreate(savedInstanceState: Bundle?) { 
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    startScanning() 
}

private fun startScanning() {
codeScanner.decodeCallback = DecodeCallback {
            runOnUiThread {
                callAPI(it.text)
            }}}

//Here I want to take the barcodeScanned 
private fun callAPI(result: String) {
        println("barcode $result") 
    }

【讨论】：