I get the following error:
e: C:\Users\Eric.Almendras\Desktop\project-flutter\scann\android\app\src\main\kotlin\com\darryncampbell\datawedgeflutter\MainActivity.kt: (79, 44): Type mismatch: inferred type is String? but String was expected
e: C:\Users\Eric.Almendras\Desktop\project-flutter\scann\android\app\src\main\kotlin\com\darryncampbell\datawedgeflutter\MainActivity.kt: (79, 54): Type mismatch: inferred type is String? but String was expected
I can't solve it.. my code is the following:
MainActivity.kt
package com.darryncampbell.datawedgeflutter
import android.content.*
import android.os.Bundle
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.EventChannel
import io.flutter.plugin.common.EventChannel.EventSink
import io.flutter.plugin.common.EventChannel.StreamHandler
import io.flutter.plugin.common.MethodChannel
import org.json.JSONObject
import java.text.SimpleDateFormat
import java.util.*
import io.flutter.plugins.GeneratedPluginRegistrant;
class MainActivity: FlutterActivity() {
private val COMMAND_CHANNEL = "com.darryncampbell.datawedgeflutter/command"
private val SCAN_CHANNEL = "com.darryncampbell.datawedgeflutter/scan"
private val PROFILE_INTENT_ACTION = "com.darryncampbell.datawedgeflutter.SCAN"
private val PROFILE_INTENT_BROADCAST = "2"
private val dwInterface = DWInterface()
override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
GeneratedPluginRegistrant.registerWith(flutterEngine)
EventChannel(flutterEngine.dartExecutor, SCAN_CHANNEL).setStreamHandler(
object : StreamHandler {
private var dataWedgeBroadcastReceiver: BroadcastReceiver? = null
override fun onListen(arguments: Any?, events: EventSink?) {
dataWedgeBroadcastReceiver = createDataWedgeBroadcastReceiver(events)
val intentFilter = IntentFilter()
intentFilter.addAction(PROFILE_INTENT_ACTION)
intentFilter.addAction(DWInterface.DATAWEDGE_RETURN_ACTION)
intentFilter.addCategory(DWInterface.DATAWEDGE_RETURN_CATEGORY)
registerReceiver(
dataWedgeBroadcastReceiver, intentFilter)
}
override fun onCancel(arguments: Any?) {
unregisterReceiver(dataWedgeBroadcastReceiver)
dataWedgeBroadcastReceiver = null
}
}
)
MethodChannel(flutterEngine.dartExecutor, COMMAND_CHANNEL).setMethodCallHandler { call,
result ->
if (call.method == "sendDataWedgeCommandStringParameter")
{
val arguments = JSONObject(call.arguments.toString())
val command: String = arguments.get("command") as String
val parameter: String = arguments.get("parameter") as String
dwInterface.sendCommandString(applicationContext, command, parameter)
// result.success(0); // DataWedge does not return responses
}
else if (call.method == "createDataWedgeProfile")
{
createDataWedgeProfile(call.arguments.toString())
}
else {
result.notImplemented()
}
}
}
private fun createDataWedgeBroadcastReceiver(events: EventSink?): BroadcastReceiver? {
return object : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
if (intent.action.equals(PROFILE_INTENT_ACTION))
{
// A barcode has been scanned
var scanData =
intent.getStringExtra(DWInterface.DATAWEDGE_SCAN_EXTRA_DATA_STRING)
var symbology =
intent.getStringExtra(DWInterface.DATAWEDGE_SCAN_EXTRA_LABEL_TYPE)
var date = Calendar.getInstance().getTime()
var df = SimpleDateFormat("dd/MM/yyyy HH:mm:ss")
var dateTimeString = df.format(date)
var currentScan = Scan(scanData, symbology, dateTimeString);
events?.success(currentScan.toJson())
}
// Could handle return values from DW here such as RETURN_GET_ACTIVE_PROFILE
// or RETURN_ENUMERATE_SCANNERS
}
}
}
private fun createDataWedgeProfile(profileName: String) {
// Create and configure the DataWedge profile associated with this application
// For readability's sake, I have not defined each of the keys in the DWInterface file
dwInterface.sendCommandString(this, DWInterface.DATAWEDGE_SEND_CREATE_PROFILE,
profileName)
val profileConfig = Bundle()
profileConfig.putString("PROFILE_NAME", profileName)
profileConfig.putString("PROFILE_ENABLED", "true") // These are all strings
profileConfig.putString("CONFIG_MODE", "UPDATE")
val barcodeConfig = Bundle()
barcodeConfig.putString("PLUGIN_NAME", "BARCODE")
barcodeConfig.putString("RESET_CONFIG", "true") // This is the default but never hurts to
specify
val barcodeProps = Bundle()
barcodeConfig.putBundle("PARAM_LIST", barcodeProps)
profileConfig.putBundle("PLUGIN_CONFIG", barcodeConfig)
val appConfig = Bundle()
appConfig.putString("PACKAGE_NAME", packageName) // Associate the profile with this
app
appConfig.putStringArray("ACTIVITY_LIST", arrayOf("*"))
profileConfig.putParcelableArray("APP_LIST", arrayOf(appConfig))
dwInterface.sendCommandBundle(this, DWInterface.DATAWEDGE_SEND_SET_CONFIG, profileConfig)
profileConfig.remove("PLUGIN_CONFIG")
val intentConfig = Bundle()
intentConfig.putString("PLUGIN_NAME", "INTENT")
intentConfig.putString("RESET_CONFIG", "true")
val intentProps = Bundle()
intentProps.putString("intent_output_enabled", "true")
intentProps.putString("intent_action", PROFILE_INTENT_ACTION)
intentProps.putString("intent_delivery", PROFILE_INTENT_BROADCAST) // "2"
intentConfig.putBundle("PARAM_LIST", intentProps)
profileConfig.putBundle("PLUGIN_CONFIG", intentConfig)
dwInterface.sendCommandBundle(this, DWInterface.DATAWEDGE_SEND_SET_CONFIG, profileConfig)
}
}
Scan.kt
package com.darryncampbell.datawedgeflutter
import org.json.JSONObject;
class Scan(val data: String, val symbology: String, val dateTime: String)
{
fun toJson(): String{
return JSONObject(mapOf(
"scanData" to this.data,
"symbology" to this.symbology,
"dateTime" to this.dateTime
)).toString();
}
}
can someone see my mistake?
CodePudding user response：
kotlin is designed in a null safe matter. String? basically means, a String that can possibly be null. So kotlin disallows assigning String? where it expects String.
Your error says exactly where it happens.
MainActivity.kt: (79, 44) in your log means it's on line 79 of your code.
I'm guessing it's the line
var currentScan = Scan(scanData, symbology, dateTimeString);
scanData and symbology are of type String? but Scan requires String there. One easy way to convert it is to write it as
var currentScan = Scan(scanData!!, symbology!!, dateTimeString);
With !! you basically say, "I'm sure this is not null". The code will crash though if it does happen to be null
CodePudding user response：
This is related to null safety in Kotlin. Your are inferring string as nullable , but where it is being used, it is expecting it as non nullable string. You can check for null before using it or have a mechanism to check null values and handle it.
Check this link for more detailed description for nullable variables