如何使用 android studio 在 kotlin 代码中添加 try/catch？

Question

使用 android studio 时，我必须在我的 kotlin 代码中添加 try/catch，但不明白如何添加。下面是我必须添加 try/catch 的代码。

我还没有尝试任何东西，因为我完全困惑在哪里应用 try/catch。

1.

class SmsReceiver : BroadcastReceiver(){
    override fun onReceive(context: Context?, intent: Intent) {

        val extras = intent.extras

        if(extras != null){

            val sms: Array<Any> = extras.getString("pdus") as Array<Any>

            for(i in sms.indices){
                val format = extras.getString("format")

                var smsMessage = if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
                    SmsMessage.createFromPdu(sms[i] as ByteArray,format)
                }else{
                    SmsMessage.createFromPdu(sms[i] as ByteArray)
                }

                var phoneNumber = smsMessage.originatingAddress
                val messageText = smsMessage.messageBody.toString()

                Toast.makeText(context,"$phoneNumber:(Private)\n" + "messageText: $messageText",Toast.LENGTH_SHORT).show()
            }
        }
    }

}

2.

class MainActivity :AppCompatActivity(){

    private val requestReceiveSms: Int = 3

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        if(ActivityCompat.checkSelfPermission(this,android.Manifest.permission.RECEIVE_SMS) !=
            PackageManager.PERMISSION_GRANTED){
            ActivityCompat.requestPermissions(this, arrayOf(android.Manifest.permission.RECEIVE_SMS),
                requestReceiveSms)
        }

    }
}

我原以为“短信收到 Toast 消息”，但我收到“不幸的是，应用程序已停止”并崩溃了..

Answer 1

try {
    if(extras != null){

        val sms: Array<Any> = extras.getString("pdus") as Array<Any>

        for(i in sms.indices){
            val format = extras.getString("format")

            var smsMessage = if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
                SmsMessage.createFromPdu(sms[i] as ByteArray,format)
            }else{
                SmsMessage.createFromPdu(sms[i] as ByteArray)
            }

            var phoneNumber = smsMessage.originatingAddress
            val messageText = smsMessage.messageBody.toString()

            Toast.makeText(context,"$phoneNumber:(Private)\n" + "messageText: $messageText",Toast.LENGTH_SHORT).show()
        }
    }
}catch (ex:Exception){
   //your error handling code here
   //here, consider adding Log.e("SmsReceiver", ex.localizedMessage)
   //this log statement simply prints errors to your android studio terminal and will help with debugging, alternatively leave it out 
        if (context != null){
            Toast.makeText(context!!,ex.localizedMessage, Toast.LENGTH_SHORT).show()  
           }
}

您应该对可能引发异常的代码应用 try catch。对于您发布的代码，有几个地方可能会崩溃，例如索引越界 ( sms[i]) 或 if ( extras.getString("pdus") 无法找到此键，因此我的解决方案将这两个都包含在同一个 try catch 中，您需要什么然后做例外取决于你。

如果你想处理更具体的异常，你也可以这样做：

try {
            if(extras != null){

                val sms: Array<Any> = extras.getString("pdus") as Array<Any>

                for(i in sms.indices){
                    val format = extras.getString("format")

                    var smsMessage = if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
                        SmsMessage.createFromPdu(sms[i] as ByteArray,format)
                    }else{
                        SmsMessage.createFromPdu(sms[i] as ByteArray)
                    }

                    var phoneNumber = smsMessage.originatingAddress
                    val messageText = smsMessage.messageBody.toString()

                    Toast.makeText(context,"$phoneNumber:(Private)\n" + "messageText: $messageText",Toast.LENGTH_SHORT).show()
                }
            }
        }catch (indexOutOfBoundsException:IndexOutOfBoundsException){
           //your error handling code here
        } catch (nullpointer : NullPointerException){
          //your error handling code here
        }