FileDocCategorySizeDatePackage
StringReader.javaAPI DocJava SE 5 API5108Fri Aug 26 14:57:00 BST 2005java.io

StringReader

public class StringReader extends Reader
A character stream whose source is a string.
version
1.24, 04/02/19
author
Mark Reinhold
since
JDK1.1

Fields Summary
private String
str
private int
length
private int
next
private int
mark
Constructors Summary
public StringReader(String s)
Create a new string reader.

param
s String providing the character stream.


                      
       
	this.str = s;
	this.length = s.length();
    
Methods Summary
public voidclose()
Close the stream.

	str = null;
    
private voidensureOpen()
Check to make sure that the stream has not been closed

	if (str == null)
	    throw new IOException("Stream closed");
    
public voidmark(int readAheadLimit)
Mark the present position in the stream. Subsequent calls to reset() will reposition the stream to this point.

param
readAheadLimit Limit on the number of characters that may be read while still preserving the mark. Because the stream's input comes from a string, there is no actual limit, so this argument must not be negative, but is otherwise ignored.
exception
IllegalArgumentException If readAheadLimit is < 0
exception
IOException If an I/O error occurs

	if (readAheadLimit < 0){
	    throw new IllegalArgumentException("Read-ahead limit < 0");
	}
	synchronized (lock) {
	    ensureOpen();
	    mark = next;
	}
    
public booleanmarkSupported()
Tell whether this stream supports the mark() operation, which it does.

	return true;
    
public intread()
Read a single character.

return
The character read, or -1 if the end of the stream has been reached
exception
IOException If an I/O error occurs

	synchronized (lock) {
	    ensureOpen();
	    if (next >= length)
		return -1;
	    return str.charAt(next++);
	}
    
public intread(char[] cbuf, int off, int len)
Read characters into a portion of an array.

param
cbuf Destination buffer
param
off Offset at which to start writing characters
param
len Maximum number of characters to read
return
The number of characters read, or -1 if the end of the stream has been reached
exception
IOException If an I/O error occurs

	synchronized (lock) {
	    ensureOpen();
            if ((off < 0) || (off > cbuf.length) || (len < 0) ||
                ((off + len) > cbuf.length) || ((off + len) < 0)) {
                throw new IndexOutOfBoundsException();
            } else if (len == 0) {
                return 0;
            }
	    if (next >= length)
		return -1;
	    int n = Math.min(length - next, len);
	    str.getChars(next, next + n, cbuf, off);
	    next += n;
	    return n;
	}
    
public booleanready()
Tell whether this stream is ready to be read.

return
True if the next read() is guaranteed not to block for input
exception
IOException If the stream is closed

        synchronized (lock) {
        ensureOpen();
        return true;
        }
    
public voidreset()
Reset the stream to the most recent mark, or to the beginning of the string if it has never been marked.

exception
IOException If an I/O error occurs

	synchronized (lock) {
	    ensureOpen();
	    next = mark;
	}
    
public longskip(long ns)
Skips the specified number of characters in the stream. Returns the number of characters that were skipped.

The ns parameter may be negative, even though the skip method of the {@link Reader} superclass throws an exception in this case. Negative values of ns cause the stream to skip backwards. Negative return values indicate a skip backwards. It is not possible to skip backwards past the beginning of the string.

If the entire string has been read or skipped, then this method has no effect and always returns 0.

exception
IOException If an I/O error occurs

	synchronized (lock) {
            ensureOpen();
            if (next >= length)
                return 0;
            // Bound skip by beginning and end of the source
            long n = Math.min(length - next, ns);
            n = Math.max(-next, n);
            next += n;
            return n;
        }