问题描述

IO流 自定义readLine 无法读取下一行 5C

import java.io.*;
public class Demo
{
public static void main(String[] args) throws IOException
{
BufferedWriter bfw = new BufferedWriter(new FileWriter(""b.txt""));
bfw.write(""sdasdaadrn"");

    bfw.write(""1"");    bfw.close();    myreadline bfr = new myreadline(new FileReader(""b.txt""));    String s = null;    while((s = bfr.method()) != null)    {        sop(s);    }    bfr.myclose();}public static void sop(Object obj){    System.out.println(obj);}

}

class myreadline extends Reader
{
private FileReader r ;
myreadline(FileReader r)
{
this.r = r;
}

public String method() throws IOException{    StringBuilder sb = new StringBuilder();    int ch =0;    while((ch = r.read()) != -1)    {        if( ch == 'r')            continue;        if(ch == 'n')            return sb.toString();        else            sb.append((char)ch);    }    return null;}public void myclose()throws IOException{    r.close();}public void close()throws IOException{    r.close();}public int read(char[] c  int a  int b) throws IOException{    return r.read(c a  b);}

}

为什么只能读取一行呢？？？

解决方案

StringBuilder sb = new StringBuilder();
这个sb放在局部变量里，每次调用都不会再有之前读取的缓冲的字符了。