使用ArrayList将对象保存至txt文件及其读取

保存文件

public void SaveFile(List users,String filename) throws IOException {

        File file = new File(filename);
        //创建文件输出流
        FileOutputStream fos = new FileOutputStream(file);
        //创建对象输出流
        ObjectOutputStream oos =new ObjectOutputStream(fos);
        //保存对象
        oos.writeObject(users);
    }

读取文件

public ArrayList loadFile(String filename) throws IOException, ClassNotFoundException {//file 为写入的文件

        File file = new File(filename);
        if(file.length()>0) {
            //创建文件输入流
            FileInputStream fis = new FileInputStream(file);
            //创建对象输入流
            ObjectInputStream ois = new ObjectInputStream(fis);
            //读取文件中的对象
            ArrayList h2 = (ArrayList) ois.readObject();
            //遍历list
            for (int i = 0; i < h2.size(); i++) {
                System.out.println(h2.get(i));
            }
            System.out.println("success");
            return h2;
        }else {
            //第一次添加时文件为空，返回空值
            System.out.println("null");
            return null;
        }
    }