Casting a java Object to Object[] in Scala

Question

Hi working on an Android SMS application in scala alls going fine expect I just cant find the way to write the following java code in scala. Any help appreciated

//---retrieve the SMS message received---
    Object[] pdus = (Object[]) bundle.get("pdus");  
    msgs = new SmsMessage[pdus.length];             
        for (int i=0; i<msgs.length; i++){  
            msgs[i] = SmsMessage.createFromPdu((byte[])pdus[i]);

I must admit I dont know how to write Object[] in scala its not java.util.ArrayList[java.lang.Object] I have tried using the Bundle.getStringArrayList to get a List[String] and the do a getBytes on the strings but that not working ... My last attempt was:

//I know I should be using an Option ...  
def getSmsListFromIntent(intent:Intent):List[SmsMessage]= {  
    val bundle = intent.getExtras()  
    var ret:List[SmsMessage]= null  
    if (bundle != null)   
        ret= for { pdu <- bundle.getStringArrayList("pdus").toList } yield  
SmsMessage.createFromPdu( pdu.getBytes())
    else ret= List()  
    ret

java code comes from: http://mobiforge.com/developing/story/sms-messaging-android Thanks for any help

score 11 · Accepted Answer · 2011-09-13 19:36:46Z

11

The following answers the question in the title and may not be the best way to approach the problem. Take it for what it's worth.

The literal translation of a cast in Scala is asInstanceOf:

var x: Object = Array("foo", "bar");
var y = x.asInstanceOf[Array[Object]];    
>> x: java.lang.Object = Array(foo, bar)
>> y: Array[java.lang.Object] = Array(foo, bar)

However, as a fun exercise, why does this result in a ClassCastException?

var x: Object = Array(1, 2);
var y = x.asInstanceOf[Array[Object]];

Happy coding

edited Sep 13, 2011 at 19:36

answered Sep 13, 2011 at 19:27

user166390

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user433320 · Accepted Answer · 2011-09-20 19:25:42Z

0

Just for completness this is what I ended up writing with pst's suggestion:

    def getSmsListFromIntent(intent:Intent)= {
    val bundle = intent.getExtras()
        if (bundle != null) {
         bundle.get("pdus")
               .asInstanceOf[Array[Object]]
               .map(pdu => SmsMessage.createFromPdu( pdu.asInstanceOf[Array[Byte]] ))
        } else  Array[SmsMessage]()
}

answered Sep 20, 2011 at 19:25

user433320

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