Required text fields in java swing form

Question

制作一个允许用户更新编辑并从表单中删除客户详细信息的表单，有没有办法使用格式化文本字段或任何代码来简单地验证必填字段？

Answer 1

Not out of the box. And it all depends a bit on what you want to do after validation, eg show a message or make the field background red, ...

But simplest way would be to create a validate method in which you handle all validations, and call the validate method from listeners attached to your components and possible buttons as you like.

Rudimentary sample:

private void createForm(){
  ...

  textField1.getDocument().addDocumentListener(new DocumentListener() {
    public void changedUpdate(DocumentEvent e) {
      validate();
    }
    public void removeUpdate(DocumentEvent e) {
      validate();
    }
    public void insertUpdate(DocumentEvent e) {
      validate();
    }
  });

  JButton button = new JButton("Next");
  button.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
      boolean valid = validate();

      if(valid) {
        next();
      }
    }
  });

  ...
}


private boolean validate(){
  StringBuilder errorText = new StringBuilder();

  if(textField1.getText().length() == 0){
    errorText.append("Textfield 1 is mandatory\n");
    field1.setBackground(Color.red);
  }

  if(textField2.getText().length() == 0){
    errorText.append("Textfield 2 is mandatory");
    field2.setBackground(Color.red);
  }

  // Show the errorText in a message box, or in a label, or ...

  return errorText.lenght() == 0;
}