保持jButton为灰色，直到jTextFields！= null [英] keep jButton grey until jTextFields != null

问题描述

我有4个jTextField，一旦按下提交按钮，我会将输入保存到文件中.我希望能够保持禁用提交按钮，直到每个字段至少不为null为止.我在哪里可以放这样的东西

I have 4 jTextFields that I save the input to a file once a submit button is pressed. I want to be able to keep the submit button disabled until each field is at least not null. Where can i put something like this

    if(jTextField1 == null || jTextField2 == null || jTextField3 == null || jTextField4 == null){
        jButton2.setEnabled(false);
    }

，以便程序将启用/禁用实时按钮.就像最后一个字段中甚至有1个字符一样，我是否希望启用它?

so that the program will enable/disable the button live. Like once the last field even has 1 character in it I want it to be enabled?

推荐答案

您需要添加侦听器以检测用户何时输入文本.为了让它注册任何更改(而不仅仅是在用户按下 Enter 时)，您应该将 DocumentListener 附加到每个 JTextField .

You need to add listeners to detect when the user enters text. In order to have it register any change (and not just when the user hits Enter) you should attach a DocumentListener to the underlying document of each JTextField.

然后，让每个侦听器调用一个函数来进行检查并相应地更新 JButton 的 enabled 状态.

Then, have each listener call a function to do your check and update the JButton's enabled status accordingly.

相关

这篇关于保持jButton为灰色，直到jTextFields！= null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！