帮我实现一下吧!我做不出来
------解决方案--------------------
for example
- Java code
BufferedReader br = new BufferedReader(new FileReader("test.txt"));PrintStream ps = new PrintStream(new FileOutputStream("test.txt.new"));String buf;int count = 0;while ((buf=br.readLine()) != null) { count++; if (count == 4) { buf = buf.replaceAll("xxx", "yyy"); } ps.println(buf);}br.close();ps.close();File f1 = new File("test.txt");f1.delete();File f2 = new File("test.txt.new");f2.renameTo(f1);