Method read

src/main/java/org/apache/commons/io/IOUtils.java:2854–2869

Reads characters from an input character stream. This implementation guarantees that it will read as many characters as possible before giving up; this may not always be the case for subclasses of Reader. @param input where to read input from @param buffer destination @param offset initial

(final Reader input, final char[] buffer, final int offset, final int length)

     * @since 2.2
     */
    public static int read(final Reader input, final char[] buffer, final int offset, final int length)
            throws IOException {
        if (length < 0) {
            throw new IllegalArgumentException("Length must not be negative: " + length);
        }
        int remaining = length;
        while (remaining > 0) {
            final int location = length - remaining;
            final int count = input.read(buffer, offset + location, remaining);
            if (EOF == count) { // EOF
                break;
            }
            remaining -= count;
        }
        return length - remaining;
    }

    /**
     * Reads characters from an input character stream.