java - 使用时间延迟将 Swing 组件中字符串数组的内容显示为迭代。 JAVA

Question

我有一个字符串数组，我试图在 Java Swing 组件中将其显示为幻灯片(一个接一个)。我还尝试在迭代之间添加延迟时间。

我试图通过使用 JTextArea 来做到这一点，并向其中添加了一个 Action 监听器。这是我现在拥有的代码:

private class myActionListener implements ActionListener {
    public void actionPerformed(ActionEvent e) {
        // A BUNCH OF TEXT PROCESSING

        //NOTE: myInfo.getContents() returns an ArrayList<myType>.
        Iterator<myType> iterator = myInfo.getContents().iterator();

        int i = 0;
        while (iterator.hasNext()) {
            myTextArea.setText(iterator.next().toString());
            // to add time betweeen iterations i wanted to use the thread
            // delay method.
        }
    }
}

我的代码无法正常工作，因为 JTextArea 没有 Action 监听器。

更新注意:许多回复说我应该为 JTextArea 使用 ActionListener；但是，Eclipse 没有向我显示 JTextArea 有一个名为 addActionListener 的方法。

我有点卡住了，您认为哪种 Java Swing 组件最适合这种情况？

我数组中的文本可能很长，因此单行标签不是一个好的选择。

我还有哪些其他选择或方法？

非常感谢，任何帮助和建议都将不胜感激。

Answer 1

这是基于@Robin 发布的建议的基本示例

public class TestDisplayString {

    public static void main(String[] args) {
        new TestDisplayString();
    }

    public TestDisplayString() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException ex) {
                } catch (InstantiationException ex) {
                } catch (IllegalAccessException ex) {
                } catch (UnsupportedLookAndFeelException ex) {
                }

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }

        });
    }

    public class TestPane extends JPanel {

        private JTextArea textArea;
        private List<String> content;
        private Iterator<String> iterator;

        public TestPane() {
            readText();
            setLayout(new BorderLayout());
            textArea = new JTextArea(10, 40);
            textArea.setLineWrap(true);
            textArea.setWrapStyleWord(true);
            add(new JScrollPane(textArea));
            iterator = content.iterator();

            Timer timer = new Timer(1000, new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    if (iterator.hasNext()) {
                        textArea.setText(iterator.next());
                    } else {
                        ((Timer)e.getSource()).stop();
                    }
                }
            });
            timer.setRepeats(true);
            timer.setCoalesce(true);
            timer.start();
        }

        protected void readText() {
            content = new ArrayList<>(25);
            BufferedReader reader = null;
            try {
                reader = new BufferedReader(new InputStreamReader(getClass().getResourceAsStream("/Text.txt")));
                String text = null;
                while ((text = reader.readLine()) != null) {
                    if (text.trim().length() > 0) {
                        content.add(text);
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                try {
                    reader.close();
                } catch (Exception e) {
                }
            }
        }

    }

}

这是“Text.txt”文件的内容。

How to Use Swing Timers

A Swing timer (an instance of javax.swing.Timer) fires one or more action events after a specified delay. Don't confuse Swing timers with the general-purpose timer facility that was added to the java.util package in release 1.3. This page describes only Swing timers.

In general, we recommend using Swing timers rather than general-purpose timers for GUI-related tasks because Swing timers all share the same, pre-existing timer thread and the GUI-related task automatically executes on the event-dispatch thread. However, you might use a general-purpose timer if you don't plan on touching the GUI from the timer, or need to perform lengthy processing.

You can use Swing timers in two ways:

To perform a task once, after a delay.
For example, the tool tip manager uses Swing timers to determine when to show a tool tip and when to hide it.
To perform a task repeatedly.
For example, you might perform animation or update a component that displays progress toward a goal.

Swing timers are very easy to use. When you create the timer, you specify an action listener to be notified when the timer "goes off". The actionPerformed method in this listener should contain the code for whatever task you need to be performed. When you create the timer, you also specify the number of milliseconds between timer firings. If you want the timer to go off only once, you can invoke setRepeats(false) on the timer. To start the timer, call its start method. To suspend it, call stop.

Note that the Swing timer's task is performed in the event dispatch thread. This means that the task can safely manipulate components, but it also means that the task should execute quickly. If the task might take a while to execute, then consider using a SwingWorker instead of or in addition to the timer. See Concurrency in Swing for instructions about using the SwingWorker class and information on using Swing components in multi-threaded programs.

Let's look at an example of using a timer to periodically update a component. The TumbleItem applet uses a timer to update its display at regular intervals. (To see this applet running, go to How to Make Applets. This applet begins by creating and starting a timer:

timer = new Timer(speed, this); timer.setInitialDelay(pause); timer.start();

The speed and pause variables represent applet parameters; as configured on the other page, these are 100 and 1900 respectively, so that the first timer event will occur in approximately 1.9 seconds, and recur every 0.1 seconds. By specifying this as the second argument to the Timer constructor, TumbleItem specifies that it is the action listener for timer events.

After starting the timer, TumbleItem begins loading a series of images in a background thread. Meanwhile, the timer events begin to occur, causing the actionPerformed method to execute:

public void actionPerformed(ActionEvent e) { //If still loading, can't animate. if (!worker.isDone()) { return; }

loopslot++;

if (loopslot >= nimgs) {
    loopslot = 0;
    off += offset;

    if (off < 0) {
        off = width - maxWidth;
    } else if (off + maxWidth > width) {
        off = 0;
    }
}

animator.repaint();

if (loopslot == nimgs - 1) {
    timer.restart();
} }

Until the images are loaded, worker.isDone returns false, so timer events are effectively ignored. The first part of the event handling code simply sets values that are employed in the animation control's paintComponent method: loopslot (the index of the next graphic in the animation) and off (the horizontal offset of the next graphic).

Eventually, loopslot will reach the end of the image array and start over. When this happens, the code at the end of actionPerformed restarts the timer. Doing this causes a short delay before the animation sequence begins again.