Writer and PrintWriter

[yzzzzz]

Hi,

What is the difference between PrintWriter.write(String) and
PrintWriter.print(String)?

And how can PrintWriter.write not throw IOException when Writer.write
does? Should the overriding method have the same signature?

Thanks.

 

[Roland]

Hi,

What is the difference between PrintWriter.write(String) and
PrintWriter.print(String)?

PrintWriter.print(String) prints the literal string "null" if the
argument is null. Otherwise it's the same as PrintWriter.write(String)
Source from 1.4.2
public void print(String s) {
if (s == null) {
s = "null";
}
write(s);
}

And how can PrintWriter.write not throw IOException when Writer.write
does? Should the overriding method have the same signature?

Thanks.

The signature of a method does not include the thrown exceptions, only
its name, and the number and types of its parameters. See JLS §8.4.2
<http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#38649>

And from JLS §8.4.4
<http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#78323>:
"A method that overrides or hides another method [...] may not be
declared to throw more checked exceptions than the overridden or hidden
method."
In other words, a method overriding a method of a parent class may be
declared with fewer checked exceptions.
--
Regards,

Roland de Ruiter
___ ___
/__/ w_/ /__/
/ \ /_/ / \

 

[yzzzzz]

PrintWriter.print(String) prints the literal string "null" if the
argument is null. Otherwise it's the same as PrintWriter.write(String)
Source from 1.4.2
public void print(String s) {
if (s == null) {
s = "null";
}
write(s);
}

Hm. Weird!

And how can PrintWriter.write not throw IOException when Writer.write
does? Should the overriding method have the same signature?

Thanks.

The signature of a method does not include the thrown exceptions, only
its name, and the number and types of its parameters. See JLS §8.4.2
<http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#38649>

And from JLS §8.4.4
<http://java.sun.com/docs/books/jls/second_edition/html/classes.doc.html#78323>:

"A method that overrides or hides another method [...] may not be
declared to throw more checked exceptions than the overridden or hidden
method."
In other words, a method overriding a method of a parent class may be
declared with fewer checked exceptions.

Ok. That does make sense.