Java IO.pdf - Nguyen Dang Binh

Java I/O
Since string objects are immutable, the data in the string may not be changed after the
StringReader is constructed. The current position from which characters are read is stored in
a private field. Synchronization and thread safety are thus not major problems for this class.
Of course, the class has the usual read() methods, all of which read as many characters as
requested from the string:
public int read() throws IOException
public int read(char[] buffer, int offset, int length) throws IOException
These methods return -1 if the end of the string has been reached. They throw an
IOException if the reader has been closed.
The skip() method skips forward in the string the specified number of places and returns the
number of characters skipped. It throws an IOException if the reader is closed.
public long skip(long n) throws IOException
The ready() method returns true. Strings are always ready to be read.
public boolean ready() throws IOException
String readers support marking and resetting to the limit of the string's length.
markSupported() returns true. mark() marks the current position in the stream. (The
readAheadLimit argument is for compatibility only; its value is ignored.) The reset()
method moves backward in the string to the marked position.
public boolean markSupported()
public void mark(int readAheadLimit) throws IOException
public void reset() throws IOException
Finally, the close() method sets the internal string data to null. Attempts to read from a
StringReader after it's been closed throw IOExceptions.
public void close()
Here's a simple method that uses StringReader to break a string into its separate characters
and print them:
public static void printCharacters(String s) {
}
StringReader sr = new StringReader(s);
try {
int c;
while ((c = sr.read()) != -1) {
System.out.println((char) c);
}
}
catch (IOException e) {System.err.println(e);}
return;
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