求一个修改txt文档内容的java源码

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
public class Test {
public static void main(String[] args) {
BufferedReader reader = null;
BufferedWriter writer = null;
try {
reader = new BufferedReader(new FileReader(new File("test.txt")));
writer = new BufferedWriter(new FileWriter(new File("test1.txt")));
String line;
while ((line = reader.readLine()) != null) {
line = line.substring(5) + ";";
writer.write(line);
writer.newLine();
}
writer.write("%");
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (writer != null) {
try {
writer.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}本回答被提问者采纳

public static void main(String[] args) {
try {
File file = new File("C:\\old.txt");
File rs = new File("C:\\new.txt");
rs.createNewFile();

if (file.isFile() && file.exists()) {
InputStreamReader inputStreamReader = new InputStreamReader(new FileInputStream(file),"utf-8");
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
FileWriter fileWriter = new FileWriter(rs);
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
String line;
while ((line=bufferedReader.readLine()) != null) {
System.out.println(line.substring(5));
bufferedWriter.write(line.substring(5)+";\r\n");
}
bufferedWriter.write("%");
bufferedWriter.flush();

} else {
System.out.println("文件不存在");
}
} catch (Exception e) {
e.printStackTrace();
}
}