Java 1.5 StringBuffer/StringBuilder

[Tom Johnson]

Hi,
I have recently started using JDK1.5. I used to have code like the following :

   
String string = null;
StringBuffer stringBuffer = null;
final BufferedReader bufferReader = new BufferedReader(reader);
 
while((string = bufferReader.readLine()) != null){
             stringBuffer = new StringBuffer(string).append("\n"); // **
             listChanges.append(stringBuffer.toString());      
}

This works fine in JDK1.4. However, when this is recompiled with 1.5.0_06, i get a compile time error at line **
"Type mismatch: cannot convert from AbstractStringBuilder to StringBuffer"

This is unexpected as the append method returns a StringBuffer object, not AbstractStringBuilder object.
Also, if you pass in a char ('c'), i get a compiler error "Cannot convert from Appendable to StringBuffer", even though again the append(), method returns a StringBuffer object.

Has anyone seen this before or can anyone explain why the method is returning a different object to that which its signature defined.

Cheers

/Tom

[Keith Lynn]

Are you using an IDE? I tried compiling your code at the command line with 1.5.0_02 and didn't get a compile-time error.

[Jeff Albertson]

I'm wondering why you just don't write:

listChanges.read(reader, null);

[Tom Johnson]

Hi,
I am using the XDE IDE. Sorry I shouldnt have included the listChanges() bit, im just interested in the line **.

[Jeff Albertson]

Is listChanges a JTextArea?

[Tom Johnson]

No listChanges() is another method, it is irrelevant really for the compilation error im wondering about.

[Jeff Albertson]

Originally posted by Tom Johnson:
No listChanges() is another method, it is irrelevant really for the compilation error im wondering about.

listChanges sure looks like an object in your code:

while((string = bufferReader.readLine()) != null){
             stringBuffer = new StringBuffer(string).append("\n"); // **
             listChanges.append(stringBuffer.toString());      
}

Anyway, I would rewrite that as:

while((string = bufferReader.readLine()) != null){
    listChanges.append(string);  
    listChanges.append("\n");      
}

Although if you are trying to read into a text component, the JTextComponent read() method is the way to go.