LeetCode: Read N Characters Given Read4

/**
 * Description
 *
 * @author hzhou
 */
public class ReadNCharactersGivenReadFour extends Reader4 {
    /**
     * @param buf Destination buffer
     * @param n   Maximum number of characters to read
     * @return The number of characters read
     */
    public int read(char[] buf, int n) {
        char[] buffer = new char[4];
        int readByteCount = 0;
        boolean eof = false;
        while (readByteCount < n && !eof) {
            int c = read4(buffer);
            if (c < 4) {
                eof = true;
            }
            int bytes = Math.min(n - readByteCount, c);
            System.arraycopy(buffer, 0, buf, readByteCount, bytes);
            readByteCount += bytes;
        }
        return readByteCount;
    }
}