如何在GridLayout中更新JTextFields? [英] How to update JTextFields in a GridLayout?

问题描述

我有一个使用Gridlayout的MainPanel.因此，我分别为NORTH，EAST，CENTER和EAST布局创建了四个JPanel类.然后，将所有四个添加到我的MainPanel.

I have a MainPanel which uses the Gridlayout. Consequently I have created four JPanel classes for the: NORTH, EAST, CENTER and EAST layouts respectively. I then add all four to my MainPanel.

但是，在WEST面板上，我使用了另一个网格布局来存储JButtons和JTextFields.我要不断更新我的JTextFields，因为它们显示一个值(单击另一个面板上的按钮时会更改). JFrame运行时如何允许更改该值?

However, on my WEST panel I use another grid layout to store JButtons and JTextFields. I want to constantly update my JTextFields as they display a value (that changes when a button on another panel is clicked). How do I allow that value to be changed when the JFrame is running?

我尝试使用paintComponent，但是随着我在paintComponent方法中添加相同副本，它会继续添加同一副本JTextField的多个副本.如果我删除add方法，则值将不会更新.

I tried using paintComponent, but it keeps on adding multiple copies of the same JTextField after each other, as I add it in my paintComponent method. If I remove the add method the values won't update.

推荐答案

Action 很好地封装了此类功能.在下面的示例中，许多文本字段监听从单个 Update 按钮接收到的ActionEvent.常见的UpdateHandler源自AbstractAction.

Action works well to encapsulate such functionality. In the example below, a number of text fields listen for an ActionEvent received from a single Update button. The common UpdateHandler is derived from AbstractAction.

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

/** @see http://stackoverflow.com/a/14947144/230513 */
public class Test {

    private JButton button = new JButton("Update");

    private void display() {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(createPanel(button), BorderLayout.NORTH);
        f.add(createPanel(button), BorderLayout.WEST);
        f.add(createPanel(button), BorderLayout.EAST);
        f.add(createPanel(button), BorderLayout.SOUTH);
        JPanel p = new JPanel();
        p.add(button);
        f.add(p, BorderLayout.CENTER);
        f.getRootPane().setDefaultButton(button);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static JPanel createPanel(JButton b) {
        JPanel panel = new JPanel(new FlowLayout(FlowLayout.CENTER));
        final JTextField text = new JTextField();
        b.addActionListener(new UpdateHandler(text));
        panel.add(text);
        return panel;
    }

    private static class UpdateHandler extends AbstractAction {

        private JTextField text;
        private DateFormat df = new SimpleDateFormat("HH:mm:ss.SSS");

        public UpdateHandler(JTextField t) {
            super("update");
            t.setText(df.format(new Date()));
            this.text = t;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            text.setText(df.format(new Date()));
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Test().display();
            }
        });
    }
}

这篇关于如何在GridLayout中更新JTextFields?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！