File file = new File("E:\\a\\update.log");
StringBuffer sb = new StringBuffer();
String s = new String();
try {
BufferedReader read = new BufferedReader(new FileReader(file));
BufferedWriter writer = new BufferedWriter(new FileWriter(file));
while((s = read.readLine())!=null){
sb.append(s); \\没有读到原来文件里的内容,
sb.append("\r\n");\\运行后文件里只有一行"=========" ,哪里错了?
}
read.close();
sb.append("==========\r\n");
writer.write(sb.toString());
writer.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException ee){
ee.printStackTrace();
}
BufferedReader read = new BufferedReader(new FileReader(file));
BufferedWriter writer = new BufferedWriter(new FileWriter(file));
对同一个文件既是FileReader"读",同时又 FileWriter"写",这会清空文件内容的.
如何改正?FileWriter以添加方式"写"就行了
BufferedWriter writer = new BufferedWriter(new FileWriter(file,true));
另外建议在writer.close();之前加上:writer.flush();
移到read.close();之后。