public class Demo_1 {

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        String pwd;

        @SuppressWarnings("resource")

        Scanner input =new Scanner(System.in);

        do{

        System.out.println("请输入用户名:");

        String name = input.next();

        System.out.println("请输入密码:");

        pwd= input.next();

        if(pwd.length()<){

            System.out.println("密码长度不够");

        }else{

            System.out.println("输入正确");

            System.out.println("欢迎你！"+name);

            break;

        }

        }while(pwd.length()!=);

    }

boolean flag ;

    public  void panduan(String sfz , String sjh,String zj) {

        flag=false;

        int index=sjh.lastIndexOf("-");

    if(!(sfz.length()==||sfz.length()==)){

        System.out.println("身份证号必须是16位或18位!");

    }

    else if(sjh.length()<){

        System.out.println("手机号必须是11位!");

    }else if (index!=-&&index!=&&index!=&&zj.length()!=) {

        System.out.println("座机号码区必须为4位，电话号码必须是7位!");

    }else{

    System.out.println("注册成功");

    flag=true;

          }

    }

调用：

public static void main(String[] args) {

        @SuppressWarnings("resource")

        Scanner input=new Scanner(System.in);

        Practice2 pd =new Practice2();

        do {

            System.out.println("请输入身份证:");

            String sfz = input.next();

            System.out.println("请输入手机号码:");

            String sjh = input.next();

            System.out.println("请输入座机号:");

            String zj = input.next();

            pd.panduan(sfz, sjh, zj);

        } while (pd.flag==false);

    }