java中递归的使用，及其实例

1、// 用户信息的持久化保存（序列化）public void save(Map m) throws Exception {FileOutputStream fos = new FileOutputStream("User.txt");ObjectOutputStream oos = new ObjectOutputStream(fos);oos.writeObject(m);oos.flush();oos.close();}

2、// 用户信息的读取（反序列化）public Map read() throws Exception {FileInputStream fis = new FileInputStream("User.txt");ObjectInputStream ois = new ObjectInputStream(fis);Map<String, String> temp = (HashMap) ois.readObject();ois.close();return temp;}// 学生信息public void list(Map m) {System.out.println("列表如下：");Set<Map.Entry<String, String>> sets = m.entrySet();for (Entry<String, String> s : sets) {System.out.println(s);}}

3、// 验证并返回注册姓名public static String nameLenght(Map m) {System.out.println("请输入3位以上字母和数字组成的姓名：");String name = sc.next();//if (name.length() < 3) {//System.out.println("注册姓名小于三位，请重新输入：");//returnnameLenght(m);//}//验证姓名长度大于3并且由字母数字组成if(!(name.matches("\\w{3,}"))){System.out.println("注册姓名不符合格式！");returnnameLenght(m);}// 用于验证注册姓名是否存在Set<String> sets = m.keySet();for (String s : sets) {if (s.equals(name)) {System.out.println("用户名已存在，请重新输入：");returnnameLenght(m);}}return name;}

4、// 验证密码长度大于6public String passWordLenght() {System.out.println("请输入6位及以上密码：");String passWord = sc.next();if (passWord.length() < 6) {System.out.println("密码长度小于6，请重新输入：");//如果密码不符合要求，返回重新输入，验证，递归return passWordLenght();}System.out.println("请再次确认密码：");String passWord1 = sc.next();if (!(passWord.equals(passWord1))) {System.out.println("两次密码不一致，请重新输入：");return passWordLenght();}System.out.println("注册成功！");return passWord1;}

5、// 用户登录验证public void martch(Map m) {System.out.println("请输入姓名：");String name = sc.next();//输入姓名，在map集合查找是否存在，存在则验证密码，不存在则使用递归，返回重新输入Set<String> sets = m.keySet();for (String s : sets) {if (name.equals(s)) {martchPassWord(s, m);return;}}System.out.println("姓名不存在，请重新输入");martch(m);}

6、// 用户密码验证public void martchPassWord(String name, Map m) {System.out.println("稆糨孝汶;请输入密码");String passWord = sc.next();if (passWord.equals(m.get(name))) {System.out.println("登录成功！");return;}if (!(passWord.equals(m.get(name)))) {System.out.println("密码不正确，请重新输入");martchPassWord(name, m);}}// 学生删除public void delStudents(Map m) {System.out.println("请输入要删除的学生姓名：");String name = sc.next();Set<String> sets = m.keySet();for (String s : sets) {if (s.equals(name)) {m.remove(s);System.out.println("删除成功！");return;}}System.out.println("输入姓名不存在，删除失败！");delStudents(m);}