如何修复"lateinit property YYY has not been initialized"

Question

我有一个类，它进行蓝牙连接并从汽车中连接的 OBD 蓝牙加密狗获取 PID。 但是在调用获取 RPM 的方法时，我有一个关于不初始化该属性的异常。

class BluetoothOBDManager : OBDManager {
lateinit var context: Context
private lateinit var input: InputStream
private lateinit var output: OutputStream
private lateinit var rpmCommand: RPMCommand
private lateinit var coolantTempCommand: EngineCoolantTemperatureCommand
private lateinit var airIntakeTempCommand: AirIntakeTemperatureCommand
private lateinit var mmSocket : BluetoothSocket
fun connect(deviceString: String) {
var adapter: BluetoothAdapter = getDefaultAdapter()
val device = adapter.getRemoteDevice(deviceString)
val uuid = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB")
val mmSocket:BluetoothSocket=device.createRf....Record(uuid)
mmSocket.let { socket ->
socket.connect()
}
input = mmSocket.inputStream
output = mmSocket.outputStream
if (mmSocket.isConnected) {
println("output.write =1")
output.write(1)
}
rpmCommand = RPMCommand() //This is the INIT of the propert
}
override fun getCurrentRpm(): Int {
rpmCommand.run(input, output) // This line throughs the EXCEPTION
return rpmCommand.rpm
}
}

这就是我从另一个类调用方法的方式

BluetoothOBDManager().connect(deviceString)
var rpm  = BluetoothOBDManager().getCurrentRpm()
rpmTextView.setText(rpm)

例外

E/AndroidRuntime: FATAL EXCEPTION: main
Process: gr.obd.logger, PID: 17486
kotlin.UninitializedPropertyAccessException: lateinit property rpmCommand has not been initialized

我试图初始化方法中的属性，但没有运气

override fun getCurrentRpm(): Int {
rpmCommand = RPMCommand()
rpmCommand.run(input, output) // This line throughs the EXCEPTION
return rpmCommand.rpm
}

Answer 1

BluetoothOBDManager().connect(deviceString)
var rpm  = BluetoothOBDManager().getCurrentRpm()

您的代码创建一个BluetoothOBDManager，连接它(初始化rpmCommand(，然后将其丢弃，创建一个所有未初始化的新BluetoothOBDManager，并尝试在其上调用getCurrentRpm。它可能应该是

val obdManager = BluetoothOBDManager()
obdManager.connect(deviceString)
val rpm = obdManager.getCurrentRpm()

这并不能解释为什么你会得到

我试图初始化方法中的属性，但没有运气

但这真的不应该发生;我预计还有其他问题。