如何檢查JPassword字段是否爲

Question

我想在Swing中檢查用戶名和密碼。

此檢查適用於用戶名，但不適用於JPaswordfield。我張貼了相關代碼：

//Here I get the password 
Char[] pwd = jt1.getPassword(); 
String s = new String(pwd); //converting char to string 
String p = s; 

//In the JButton checking username and password(Username check works fine but not passwordfield) 

jb.addActionListener(new ActionListener() { 
         public void actionPerformed(ActionEvent e) 
          { 
          if ((jt.getText().length()) == 0) 
          { 
            JFrame jf1 = new JFrame("UserName"); 
             jf1.setSize(401, 401); 
             //jf1.setVisible(true); 
             jf1.setDefaultCloseOperation(jf1.EXIT_ON_CLOSE); 
             JOptionPane.showMessageDialog(jf1, "User Name is empty"); 
          } 

         else if((p.length()) == 0) 
          { 

            JFrame jf1 = new JFrame("Password"); 
             jf1.setSize(401, 401); 
             //jf1.setVisible(true); 
             jf1.setDefaultCloseOperation(jf1.EXIT_ON_CLOSE); 
             JOptionPane.showMessageDialog(jf1, "Password is empty"); 
          } 

         else if ((p.length() == 0) && (jt.getText().length()) == 0) 
          { 
            JFrame jf1 = new JFrame("UserName and Password"); 
             jf1.setSize(401, 401); 
             //jf1.setVisible(true); 
             jf1.setDefaultCloseOperation(jf1.EXIT_ON_CLOSE); 
             JOptionPane.showMessageDialog(jf1, "Username and Password is 
empty"); 
          } 

          else 
          { //go to another method} 
Can someone help 

Answer 1

很簡單的得到利用JPasswordField#getPassword()返回文本的char[]，然後簡單地獲取數組的長度和檢查的文本，如果它等於0：

JPasswordField jpf... 

if(jpf.getPassword().length == 0) { 
    // it is empty 
}else { 
    // it is not empty 
}