阅读下列代码 import java.io.*; public class Example { public static void main(String[] args) throws Exception { FileInputStream in = new FileInputStream("itcast.txt"); int b = 0; while (true) { b = in.______; if (b == -1) { break; } System.out.println(b); } in.close() } } 请说出下划线上,填写的方法名称( )