java-复制文件的4种异常处理方法

 
    private static void method4() throws IOException {
        BufferedReader br = new BufferedReader(new FileReader("fr.txt"));
        BufferedWriter bw = new BufferedWriter(new FileWriter("fw.txt"));
        try (br; bw) {

            String line;
            while ((line = br.readLine()) != null) {
                bw.write(line);
                bw.newLine();
                bw.flush();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    ;


    
    private static void method3() {

        try (BufferedReader br = new BufferedReader(new FileReader("fr.txt"));
             BufferedWrit