raf.write报错

public class RadomAccessFileTest {

public static void main(String[] args) throws IOException {

File file = new File("C:\\Users/Administrator/Desktop/a.txt");

RandomAccessFile raf = new RandomAccessFile(file,"rw");

System.out.println(raf.getFilePointer());

raf.seek(raf.length());

raf.write("a");

}

}