String.length() 给我一个错误的值

Question

每当我输入 10 个字符以下的密码时，它都会给我 Password cannot exceed 10 characters。

private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        String name = Name.getText();
        String Username = uName.getText().toString();
        String Pass1 = uPass.getPassword().toString();
        String Confirm = uConfirm.getPassword().toString();
        String Status = "OFFLINE";
        int PassLen = Pass1.length();

        if (Username.equals("") || Pass1.equals("") || Confirm.equals("") || name.equals("")) 
        {
            JOptionPane.showMessageDialog(null, "You cannot leave any fields blank when creating an Account. Please Try Again");
        } 
        else if ((uPass.getPassword().toString()).length()>10)
        {
            uPass.setText("");
            uConfirm.setText("");
            JOptionPane.showMessageDialog(null, "Password cannot exceed a maximum of 10 characters.");  
        }
        else if (!Pass1.equals(Confirm))
        {
            uConfirm.setText("");
            lblError1.setText("Passwords Do Not Match.");
            lblError2.setText("Please re-enter your Password.");
        }
        else
        {
            try {
                DB_Connect connect = new DB_Connect();
                ResultSet rs = connect.queryTbl("SELECT * FROM ACOUNTS");
                boolean AlreadyUser = false;
                String User;
                while (rs.next())
                {
                    User = rs.getString("Username");
                    if(Username.equals(User))
                    {
                        AlreadyUser = true;
                    }
                }
                if (AlreadyUser==false)
                {
                    connect.updateTbl("INSERT INTO NBUSER.ACCOUNTS (USERNAME,PASSWORD,STATUS,NAME)VALUES ('"+Username+"','"+Pass1+"','"+Status+"','"+name+"')");
                    JOptionPane.showMessageDialog(null, "Account Created Successfully !");
                    this.dispose();
                    new Topics().setVisible(true);
                }
                else
                {
                    JOptionPane.showMessageDialog(null, "The Username you have selected already exists. Please select a different Username");
                    uPass.setText("");
                    uConfirm.setText("");
                }
            } catch (SQLException ex) {
                Logger.getLogger(CreateAccount.class.getName()).log(Level.SEVERE, null, ex);
            }

        }


    }

Answer 1

由于您显然使用的是 Swing，因此您也很可能确实使用了 JPasswordField for your passwords. So let's see, what getPassword：

public char[] getPassword()

Returns the text contained in this TextComponent. If the underlying document is null, will give a NullPointerException. For stronger security, it is recommended that the returned character array be cleared after use by setting each character to zero.

Returns: the text

如您所见，它 returns 您在 char[] 中的密码，因为此 class 不会覆盖 toString 您对 uPass.getPassword().toString() 的调用结果类似于：

[C@1d44bcfa

这是调用Object#toString的结果。

此字符串的长度为 11，因此大于 10，您的 else if 块 (else if ((uPass.getPassword().toString()).length()>10)) 将被输入。

要解决这个问题，请像这样调用 String 构造函数 String(char[])：

String Pass1 = new String(uPass.getPassword());

请将其用作您当前问题的 "quick fix"，并尝试找到使用最初返回的 char[] 的方法。正如引用的 JavaDoc 所提到的，建议在使用后使用 "clean" char 数组，这样密码就不会再存储在那里。通过使用 new String(uPass.getPassword()) 从数组创建字符串，您将在堆中创建 另一个 对象，该对象包含密码并且也需要从那里删除。所以它会为你增加更多的工作。

String.length() 给我一个错误的值

String.length() gives me a wrong value

java

string

if-statement

try-catch

string-length