Question

这个问题肯定在范围之内，但是我有问题找出原因，因为我宣布了将信息存储在循环之外的变量

public Member searchMember (String email) {

    int Sid = 0;
    String name ="";
    String adr = "";
    String phone = "";
    String email2 = "";
    String pass = "";
    boolean status =false;
    Member a = new Member(name,adr,phone,email2,pass);
    try {
        Class.forName("com.mysql.jdbc.Driver");
        con = DriverManager.getConnection("jdbc:mysql://compsi:3306/mcrowley","mcrowley","700463874");
        Statement stmt = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
        System.out.println(email);
        String query = "Select id,name,address,phoneNum,email,password,LoginStatus From member WHERE email Like '%"+email+"%' ";
        ResultSet results = stmt.executeQuery(query);
        System.out.println("Before while loop");
        int count = 0;
        while (results.next() || count == 0 ) { 
            if (count == 0)
            results.absolute(1);

            System.out.println("Start while loop");
            Sid = results.getInt(1);
            //System.out.println(Sid+" this is test in jdbc");
            name = results.getString(2);
            //System.out.println(name+" this is test in jdbc");
            adr = results.getString("address");
            phone = results.getString("phoneNum");
            email2 = results.getString("email");
            pass = results.getString("password");
            int stat = results.getInt("loginStatus");
            if (stat == 0) {
                status = false;
            }
            else {
                status = true;
          }
            count++;
            if (!results.next()) {
                a.setName(name);
                a.setAddress(adr);
                a.setPhoneNumber(phone);
                a.setEmail(email2);
                a.setPassword(pass);
                a.setId(Sid);
                a.setStatus(status);
                return a;
            }
        } 
        System.out.println("After while loop");
        a.setName(name);
        a.setAddress(adr);
        a.setPhoneNumber(phone);
        a.setEmail(email2);
        a.setPassword(pass);
        a.setId(Sid);
        a.setStatus(status);
        //create object & print 
        stmt.close();
        con.close();
        return a;

    }
    catch (Exception e) {
        e.printStackTrace();
    }
    return a;
}

Answer 1

所以基本上听起来你需要一个关于the scope of variables的进修课程。

基本上，你不会带着你想知道如何解决的破解代码来到这里。但是你正在滚动，因为你认为它应该不才能工作。

以下是我记忆的方法：每个范围都可以访问自身声明的变量以及直接父级的范围。也就是说，父作用域无法读取和修改任何即将成为欢呼的声音。

所以基本上，你的问题的答案是你的直觉是不正确的。变量范围不会以您认为的方式运行。

访问循环内的数据库信息并存储在外部

1 个答案: