java在文件中删除一行 java删除某一行

public class FileUtils {
private static Logger logger = Logger.getLogger(FileUtils.class);
public static List readFirstNAddresses(String filename,int n){
BufferedReader br = null;
FileWriter fw = null;
File oldfile = new File(filename);
File newfile = new File(filename + ".tmp");
List lst = new ArrayList();
try {
br = new BufferedReader(new FileReader(oldfile));
String line;
int count = 0;
fw = new FileWriter(newfile);
while ((line = br.readLine()) != null) {
if (count < n){
//add to list as return value
try {
lst.add(new MailAddress(line));
} catch (ParseException e) {
logger.warn(e.getMessage());
}
}else{
//copy to new temp file
fw.write(line);
}
//increase count
count++;
}//read over and write over
}catch (FileNotFoundException e) {
logger.warn(e.getMessage());
e.printStackTrace();
} catch (IOException e) {
logger.warn(e.getMessage());
e.printStackTrace();
} finally{
if( br!=null)try {
br.close();
} catch (IOException e) {
e.printStackTrace();
}
if( fw!=null) try {
fw.close();
} catch (IOException e) {
e.printStackTrace();
}
}
//
if(oldfile.delete())logger.info(oldfile.getName()+"被成功删除");
else {
logger.error(oldfile.getName()+"删除失败！系统将不能正常运行");
throw new RuntimeException(oldfile.getName()+"删除失败！系统将不能正常运行");
}
if(newfile.renameTo(oldfile)) logger.info(newfile.getName()+"成功被改名为"+oldfile.getName());
else{
logger.error(newfile.getName()+"更名失败！系统将不能正常运行");
throw new RuntimeException(newfile.getName()+"更名失败！系统将不能正常运行");
}
return lst;
}
}