有没有更好的方法在 for 循环中为 JButtons 创建一个 actionListener？答案

【问题标题】：Is there a better way to create an actionListener to JButtons in a for-loop?有没有更好的方法在 for 循环中为 JButtons 创建一个 actionListener？
【发布时间】：2020-06-28 08:26:24
【问题描述】：

我想创建一些JButtons，它们象征着一个特定的时间间隔。所有JButtons 共享基本相同的actionListener：他们将其特定的间隔标记为“免费”（“Frei”）或“不免费”（“Belegt”）。为此，他们不仅必须更改文本，而且还必须调用另一个类的方法，该方法使用它们的间隔为@parameter。我创建了JButtons，命名为JLabels，如下所示：

for (int i = 1; i <= numberOfIntervalls; i++) {
            String toolTextString;
            if(controller.getCalendar(calendarName).isFree(i, controller.getDayString(year, month, day))) {
                buttonText = "Frei";
                toolTextString = "Belegt";
            }else {
                buttonText = "Belegt";
                toolTextString = "Frei";
            }
            
            if(i%5 == 0) {
                gridx = 1;
                buttonGridy += 2;
                textGridy += 2;
            }else if(i < 5){
                gridx = (i%5);
            }else {
                gridx = (i%5) + 1;
            }
            intervallButtons[i-1] = new JButton(buttonText);
            intervallButtons[i-1].addActionListener((ActionListener) this);
            intervallLabels[i-1] = new JLabel(intervallLabelBuilder(i));
            intervallButtons[i-1].setToolTipText(String.format("als %s markieren", toolTextString));
            
            GridBagConstraints gbc_btnNewButton = new GridBagConstraints();
            gbc_btnNewButton.insets = new Insets(0, 0, 0, 5);
            gbc_btnNewButton.gridx = gridx;
            gbc_btnNewButton.gridy = buttonGridy;       
            contentPane.add(intervallButtons[i-1], gbc_btnNewButton);
            
            GridBagConstraints gbc_labels = new GridBagConstraints();
            //gbc_lblNewLabel.insets = new Insets(0, 0, 5, 5);
            gbc_labels.gridx = gridx;
            gbc_labels.gridy = textGridy;
            contentPane.add(intervallLabels[i-1], gbc_labels); 
            
        }
    }

我的actionListener-方法是这样的，因为我知道numberOfIntervalls = 12，对于快速调整，numberOfIntervalls 应该是一个变量，但它s static and final`：

public void actionPerformed (ActionEvent e){
         System.out.println("-----------");
            if(e.getSource() == intervallButtons[0]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                        controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(1, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(1, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[0].setToolTipText("Als Frei markieren");
                    
                }else {
                    controller.getCalendar(calendarName).setFree(1, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[0].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[0].setText(buttonText);
                intervallButtons[0].setEnabled(false);
                intervallButtons[0].setEnabled(true);

            }else if(e.getSource() == intervallButtons[1]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                        controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                
                if(controller.getCalendar(calendarName).isFree(2, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(2, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[1].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(2, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[1].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[1].setText(buttonText);
                intervallButtons[1].setEnabled(false);
                intervallButtons[1].setEnabled(true);
            }
            else if (e.getSource() == intervallButtons[2]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(3, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(3, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[2].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(3, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[2].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[2].setText(buttonText);
                intervallButtons[2].setEnabled(false);
                intervallButtons[2].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[3]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(4, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(4, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[3].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(4, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[3].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[3].setText(buttonText);
                intervallButtons[3].setEnabled(false);
                intervallButtons[3].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[4]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(5, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(5, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[4].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(5, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[4].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[4].setText(buttonText);
                intervallButtons[4].setEnabled(false);
                intervallButtons[4].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[5]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(6, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(6, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[5].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(6, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[5].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[5].setText(buttonText);
                intervallButtons[5].setEnabled(false);
                intervallButtons[5].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[6]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(7, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(7, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[6].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(7, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[6].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[6].setText(buttonText);
                intervallButtons[5].setEnabled(false);
                intervallButtons[5].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[7]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(8, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(8, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[7].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(8, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[7].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[7].setText(buttonText);
                intervallButtons[7].setEnabled(false);
                intervallButtons[7].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[8]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(9, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(9, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[8].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(9, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[8].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[8].setText(buttonText);
                intervallButtons[8].setEnabled(false);
                intervallButtons[8].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[9]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                        controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(10, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(10, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[9].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(10, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[9].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[9].setText(buttonText);
                intervallButtons[9].setEnabled(false);
                intervallButtons[9].setEnabled(true);
                
            }else  if (e.getSource() == intervallButtons[10]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(11, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(11, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[10].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(11, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[10].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[10].setText(buttonText);
                intervallButtons[10].setEnabled(false);
                intervallButtons[10].setEnabled(true);
                
            }else if (e.getSource() == intervallButtons[11]){
                if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                    controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(12, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(12, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[11].setToolTipText("Als Frei markieren");
                }else {
                    controller.getCalendar(calendarName).setFree(12, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[11].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[11].setText(buttonText);
                intervallButtons[11].setEnabled(false);
                intervallButtons[11].setEnabled(true);
                
            }
        }

它非常长，而且只有一个变量几乎不能调整，所以我想要的只是遵循创建 for-loop 中的代码：

 if(!controller.getCalendar(calendarName).isLoaded(controller.getDayString(year, month, day)))
                        controller.getCalendar(calendarName).summonDay(controller.getDayString(year, month, day));
                if(controller.getCalendar(calendarName).isFree(1, controller.getDayString(year, month, day))) {
                    controller.getCalendar(calendarName).setFree(i, false, controller.getDayString(year, month, day));
                    buttonText = "Belegt";
                    intervallButtons[i-1].setToolTipText("Als Frei markieren");
                    
                }else {
                    controller.getCalendar(calendarName).setFree(i, true, controller.getDayString(year, month, day));
                    buttonText = "Frei";
                    intervallButtons[i-1].setToolTipText("Als Belegt markieren");
                }
                intervallButtons[i-1].setText(buttonText);
                intervallButtons[i-1].setEnabled(false);
                intervallButtons[i-1].setEnabled(true);

但它不起作用，因为actionListener 只能处理非局部变量... 你有什么想法吗？

【问题讨论】：

“他们将特定的间隔标记为“免费”（“Frei”）或“不免费”（“Belegt”）。为此，他们不仅需要更改文本“ 改用JCheckBox 或JRadioButton，则无需更改文本（或GUI 的几何形状）。为了尽快获得更好的帮助，edit 添加minimal reproducible example 或Short, Self Contained, Correct Example。只需 2 或 3 个按钮即可完成。一旦它起作用了，该技术应该很容易转移到..根据需要更多。
@AndrewThompson 这是个好主意，但我绝对需要调用controller.getCalendar(calendarName).setFree(int i, false, controller.getDayString(year, month, day)); 和int i 对于每个JButton 都不同，因为它需要是来自int i 的int i-环形。那是我的问题。
“那是我的问题。” 我的问题是我无法在我的 IDE 中读取未（编译和格式化）的代码，所以不要尝试。哦等等，这不是问题。至少对我来说不是，因为我对此的兴趣纯粹是学术性的。 MRE / SSCCE 在哪里？

标签： java swing for-loop jbutton actionlistener

【解决方案1】：

每个 JButton 的 int i 都不同，因为它必须是来自该 for 循环的 int i。

一种方法是为按钮设置“动作命令”。

当你创建你使用的按钮时：

JButton button = new JButton(...);
button.setActionCommand("" + i);

然后在你使用的 ActionListener 中：

int index = Integer.parseInt( event.getActionCommand() );

【讨论】：