java为文件添加行号题

public class TxtTest {

public static void main(String[] args) {
try {
File file = new File("d:\\file\\hello.txt");
FileReader reader = new FileReader(file);
BufferedReader bReader = new BufferedReader(reader);
ArrayList<String> list = new ArrayList<String>();
String temp = "";
int n = 0;
bp:
while (true) {
temp = bReader.readLine();
if (temp == null) {
break bp;
}
temp = n + " " + temp ;
n++;
list.add(temp);
}
bReader.close();
reader.close();
file.delete();
file.createNewFile();
FileWriter writer = new FileWriter(fi