the argument of method mark() does not work

[Kevin Lee]

 try {
FileReader fr = new FileReader(file);
BufferedReader br = new BufferedReader(fr);
System.out.println((char)br.read());
System.out.println("mark here");
br.mark(2);
System.out.println((char)br.read());
System.out.println((char)br.read());
System.out.println((char)br.read());
System.out.println((char)br.read());
System.out.println((char)br.read());
System.out.println((char)br.read());
System.out.println("reset");
br.reset();
System.out.println((char)br.read());
System.out.println((char)br.read());
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
 

I think the mark should get invalid after statement "System.out.println((char)br.read());
System.out.println((char)br.read());"
because the argument of method mark(2) is "2".but when I call reset(),the stream go to the position where I marked ,it seems mark will never be valid no matter how many byte have been read.
anybody call explain it ?
thanks

[Ernest Friedman-Hill]

Hi,

Welcome to JavaRanch!

The Javadoc says (emphasis mine

After reading this many characters, attempting to reset the stream may fail.

The actual limit may be larger than the argument to mark(); I'd guess that the actual limit is a function of the buffer size and the amount remaining in the buffer when you call "mark()". But in any case, you can't depend on failure at a specific point; rather, you must guard against failure after a specific point. Get it?

[Kevin Lee]

Originally posted by Ernest Friedman-Hill:
Hi,

Welcome to JavaRanch!

The Javadoc says (emphasis mine



The actual limit may be larger than the argument to mark(); I'd guess that the actual limit is a function of the buffer size and the amount remaining in the buffer when you call "mark()". But in any case, you can't depend on failure at a specific point; rather, you must guard against failure after a specific point. Get it?

ok,I get it.thank you very much for your kind replay