textFields上的无限焦点循环

Question

我有2个JTextFields:

JTextField txtJobType, txtPriorityCode;

这是我需要的功能:

当用户在txtJobType中键入"管理"并点击选项卡(或点击远离)时,将执行错误检查以查看该字段是否为空或输入的文本是否存在于数据库中.我这样做的方式是:

private void txtJobTypeFocusLost(java.awt.event.FocusEvent evt) {                                     
    System.out.println("JobType Focus Lost");
    if (!checkFieldExists(txtJobType.getText(), "jobType", "jobCode",
            JobType.class) || txtJobType.getText().isEmpty()) {
        txtJobType.requestFocusInWindow();
        txtJobType.selectAll();
    } else {
    }
} 

因此,如果该字段不存在或文本为空,则将焦点返回到txtJobType并突出显示所有文本(如果有)

这没有问题.但是,我有txtPriorityCode字段需要具有完全相同的行为.所以我做了:

private void txtPriorityCodeFocusLost(java.awt.event.FocusEvent evt) {                                          
    System.out.println("PriorityCode Focus Lost");
    if (!checkFieldExists(txtPriorityCode.getText(), "priority", "priorityCode",
            Priority.class) || txtPriorityCode.getText().isEmpty()) {
        txtPriorityCode.requestFocusInWindow();
        txtPriorityCode.selectAll();
    }
}

这是问题开始的地方:如果用户将jobType和制表符保留为优先级,则代码会尝试将焦点返回到jobtype,但由于此时优先级也为空,它将尝试从jobtype返回焦点,从而产生此输出:

PriorityCode Focus Lost
JobType Focus Lost
PriorityCode Focus Lost
JobType Focus Lost

任何有关如何实现此行为的帮助表示赞赏,因为我必须为至少10个其他文本字段执行此操作.

谢谢!

Answer 1

你不应该摆弄焦点丢失或其他低级构造.相反,为什么不能简单地用一个InputVerifier按照这个例子和这一个了？

例如,它看起来像这样:

import javax.swing.*;

public class InputVerifierEg {
   private JPanel mainPanel = new JPanel();
   private JTextField txtJobType = new JTextField(10);
   private JTextField txtPriorityCode = new JTextField(10);

   public InputVerifierEg() {
      txtJobType.setInputVerifier(new MyInputVerifier("jobType", "jobCode",
            JobType.class));
      txtPriorityCode.setInputVerifier(new MyInputVerifier("priority", "priorityCode",
            Priority.class));

      mainPanel.add(new JLabel("Job Type:"));
      mainPanel.add(txtJobType);
      mainPanel.add(Box.createHorizontalStrut(15));
      mainPanel.add(new JLabel("Priority Code:"));
      mainPanel.add(txtPriorityCode);

   }

   public JPanel getMainPanel() {
      return mainPanel;
   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("InputVerifierEg");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new InputVerifierEg().getMainPanel());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

class MyInputVerifier extends InputVerifier {
   private String fieldName;
   private String codeName;
   private Class<?> classType;

   public MyInputVerifier(String fieldName, String codeName, Class<?> classType) {
      this.fieldName = fieldName;
      this.codeName = codeName;
      this.classType = classType;
   }

   @Override
   public boolean verify(JComponent input) {
      JTextField tField = (JTextField) input;

      // assuming that the checkFieldExists is a static method of a utility class
      if (!FieldCheckerUtil.checkFieldExists(tField.getText(), fieldName,
            codeName, classType)) {
         return false;
      }

      if (tField.getText().trim().isEmpty()) {
         return false;
      }
      return true;
   }

   @Override
   public boolean shouldYieldFocus(JComponent input) {
      JTextField tField = (JTextField) input;

      if (verify(input)) {
         return true;
      } else {
         tField.selectAll();
         // show JOptionPane error message?
         return false;
      }
   }
}