How to deal with checked exception (UnsupportedEncodingException) that can never occurs?

I am trying transform a string to UTF-8 encoding. But the compilation fails because some code "throws UnsupportedEncodingException".

String s = "1,2,3,4";

String smsext = new String(s.getBytes(),"UTF-8");

how to solve this ?

Last updated:11/17/2014 3:04:18 AM

1 Answers

David Miller
David Miller

The exception UnsupportedEncodingException is thrown by the String constructor (not by Android Studio !!!). This is a checked exception and so your code must handle it in some way.

In this particular case : the exception will never be thrown because "UTF-8" is hardcoded and always supported by any JVM (this is a requirement). So you can catch it silently :

String s = "1,2,3,4";
String smsext = null;
try{
    smsext = new String(s.getBytes(),"UTF-8");
}catch(UnsupportedEncodingException e){
    //can never occurs
}

But I don't recommend this over simplistic approach because silently catching an exception is almost always a very bad practice. A more appropriate solution for catched exception that never append is to rethrow the exception encapsulated in a non catched exception :

String s = "1,2,3,4";
String smsext = null;
try{
    smsext = new String(s.getBytes(),"UTF-8");
}catch(UnsupportedEncodingException e){
    //can never occurs because UTF-8 is always supported
    throw new RuntimeException(e);
}

With this code, if one day you change the body of the try-catch block so that UnsupportedEncodingException can possibly occurs : the exception won't be ignored silently. 

Answer