JAVA-从动作侦听器调用时，JFrame看起来不正确 [英] JAVA - JFrame not looking proper when called from action listener
问题描述
按一下按钮调用框架时，我的一个框架看起来不正常，这是一个问题.
I have a problem with one of my frames not looking as it should, when it is called upon the press of a button.
该框架看起来好像渲染得不正确，其中的标签文本缩短了，但是当我将同一行代码移到动作侦听器之外时，它会正常工作.
The frame looks as if it was rendered improperly, the label text in it is shortened, however when i move the same line of code outside the action listener, it works as it should.
我有一个主菜单，有两个按钮，目前只有生成菜单"起作用，看起来像这样:
I have a sort of main menu, with two buttons, only the Generate Menu works at the moment, it looks like this:
https://i.imgur.com/k1Ne5v9.png
动作侦听器的代码:
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
mF.dispose();
MenuGenerator.generateTheMenu();
}
});
结果看起来不正确: https://i.imgur.com/n86y4CD.png 框架也没有响应，但单击X不会，但它应该关闭框架和应用程序.
The result looks wrong: https://i.imgur.com/n86y4CD.png The frame is also unresponsive, clikcing X does not, while it should close the frame and the application.
但是将代码更改为:
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
//mF.dispose();
}
});
MenuGenerator.generateTheMenu();
产生正确的外观: https://i.imgur.com/TFbkmAO.png
主菜单"的代码
public static void openMainMenu() {
Font menuFont = new Font("Courier",Font.BOLD,16);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mF.setSize(465,230);
mF.setLocation(dim.width/2-mF.getSize().width/2, dim.height/2-mF.getSize().height/2);
mF.getContentPane().setBackground(Color.WHITE);
Color blueSteel = new Color(70,107,176);
JPanel p = new JPanel();
p.setSize(600,50);
p.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
p.setLocation((mF.getWidth() - p.getWidth()) /2, 20);
p.setBackground(blueSteel);
JLabel l = new JLabel("Welcome to the menu GENERATORRRR");
l.setFont(menuFont);
l.setForeground(Color.WHITE);
p.add(l, gbc);
JButton runMenuButt = new JButton("Generate Menu");
runMenuButt.setLocation(20 , 90);
JButton manageRecipButt = new JButton("Manage Recipients");
manageRecipButt.setLocation(240 , 90);
menuUtilities.formatButton(runMenuButt);
menuUtilities.formatButton(manageRecipButt);
mF.setResizable(false);
mF.setLayout(null);
mF.add(runMenuButt);
mF.add(manageRecipButt);
mF.add(p);
mF.setVisible(true);
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
//mF.dispose();
}
});
MenuGenerator.generateTheMenu();
manageRecipButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JOptionPane.showMessageDialog(null, "Not supported yet", "Function not yet available",JOptionPane.INFORMATION_MESSAGE);
}
});
//System.out.println(mF.getContentPane().getSize());
}
状态栏:
public class StatusBar {
private static JLabel statusLabel= new JLabel("Starting");
private static JFrame statusFrame = new JFrame("Generation Status");
public static void createStatusBar() {
Font menuFont = new Font(Font.MONOSPACED,Font.BOLD,20);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
statusFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
statusFrame.setSize(700,100);
JPanel p = new JPanel();
p.setPreferredSize(new Dimension(100,100));
statusLabel.setFont(menuFont);
p.add(statusLabel);
statusFrame.add(p,BorderLayout.CENTER);
statusFrame.setLocation(dim.width/2-statusFrame.getSize().width/2, dim.height/2-statusFrame.getSize().height/2);
statusFrame.setVisible(true);
}
public static void setStatusBar(String statusText) {
statusLabel.setText(statusText);
statusLabel.paintImmediately(statusLabel.getVisibleRect());
statusLabel.revalidate();
}
public static void closeStatusBar(){
statusFrame.dispose();
}
}
我用这一行创建栏: StatusBar.createStatusBar();
I create the bar with this line: StatusBar.createStatusBar();
为什么当MenuGenerator.generateTheMenu();时状态栏不能正确显示.是从动作侦听器调用的?
Why does the status bar not render properly when the MenuGenerator.generateTheMenu(); is called from the action listener?
这是最小的代码，可以为想要测试它的任何人重现此行为:它也为StatusBar使用类，该类已经发布.
Here is minimal code that reproduces this behavior for anyone who would like to test it: It also uses class for the StatusBar, which is already posted.
public class MinimalClass {
private static JFrame mF = new JFrame("Main Menu");
public static void main(String[] args) {
openMainMenu();
}
public static void openMainMenu() {
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mF.setSize(465,230);
mF.setLocation(dim.width/2-mF.getSize().width/2, dim.height/2-mF.getSize().height/2);
mF.getContentPane().setBackground(Color.WHITE);
JButton runMenuButt = new JButton("Generate Menu");
runMenuButt.setLocation(20 , 90);
runMenuButt.setSize(200 , 85);
mF.setResizable(false);
mF.setLayout(null);
mF.add(runMenuButt);
mF.setVisible(true);
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
mF.dispose();
generateTheMenu();
}
});
}
public static void generateTheMenu() {
System.setProperty("sun.java2d.cmm", "sun.java2d.cmm.kcms.KcmsServiceProvider");
String rawMenuOutput = "";
try {
rawMenuOutput= getMenuInJavaNow();
} catch (Exception e){
System.out.println("Something went terribly wrong");
}
System.out.println(rawMenuOutput);
}
public static String getMenuInJavaNow() throws IOException {
String rawMenuOutput = "Restaurant Menu" ;
rawMenuOutput = rawMenuOutput + "Test line";
String []menuOtpArr = new String [3];
try {
StatusBar.createStatusBar();
TimeUnit.SECONDS.sleep(2);
StatusBar.setStatusBar("Test1");
TimeUnit.SECONDS.sleep(2);
menuOtpArr[0]="Test line";
StatusBar.setStatusBar("Test2");
TimeUnit.SECONDS.sleep(2);
menuOtpArr[1]="Test line";
StatusBar.setStatusBar("Test3");
TimeUnit.SECONDS.sleep(2);
menuOtpArr[2]="Test line";
StatusBar.setStatusBar("Test4");
TimeUnit.SECONDS.sleep(2);
StatusBar.closeStatusBar();
} catch (Exception e) {
}
for (int i=0;i < menuOtpArr.length;i++) {
rawMenuOutput = rawMenuOutput + "\n\n" +menuOtpArr[i];
}
return rawMenuOutput;
}
}
谢谢您的时间
推荐答案
statusLabel.paintImmediately(statusLabel.getVisibleRect());似乎掩盖了更大的问题.
statusLabel.paintImmediately(statusLabel.getVisibleRect()); seems to masking a larger issue.
问题是，Swing是单线程的(并且不是线程安全的).这意味着，当您从getMenuInJavaNow内调用的getMenuInJavaNow中调用TimeUnit.SECONDS.sleep(2);时，该事件在ActionListener调用中被调用，它是在事件调度线程的上下文中被调用的.
The problem is, Swing is single threaded (and NOT thread safe). This means that when you call TimeUnit.SECONDS.sleep(2); from within getMenuInJavaNow, which is called by generateTheMenu, which is called by the ActionListener, it's been called within the context of the Event Dispatching Thread.
这会使EDT处于休眠状态，这意味着它没有(正确地)处理布局或绘画请求
This is putting the EDT to sleep, meaning that it isn't processing layout or paint requests (properly)
首先阅读 Swing中的并发了解更多详情
现在，您有一个更大的问题，如何解决.对于该问题的答案，我们需要的上下文要多得多.
Now, you have a larger issue, how to solve it. For the answer to that question, we require a lot more context then is currently available.
getMenuInJavaNow似乎正在返回一些值，我不确定是什么目的.
The getMenuInJavaNow seems to be returning some values, to what end I'm not sure.
"A" solution, would be to use a SwingWorker (see Worker Threads and SwingWorker for more details). It provides the ability to execute long running tasks in the background, but also provides the means for sync updates back to the UI, for example...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GridLayout;
import java.awt.Insets;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingWorker;
public class MinimalClass {
private static JFrame mF = new JFrame("Main Menu");
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
openMainMenu();
}
});
}
public static void openMainMenu() {
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
mF.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mF.setLocationRelativeTo(null);
mF.getContentPane().setBackground(Color.WHITE);
JButton runMenuButt = new JButton("Generate Menu");
runMenuButt.setMargin(new Insets(25, 25, 25, 25));
JPanel buttons = new JPanel(new GridLayout(0, 2));
buttons.add(runMenuButt);
mF.add(buttons);
mF.pack();
mF.setVisible(true);
runMenuButt.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.out.println("Generate Menu pressed");
mF.dispose();
generateTheMenu();
}
});
}
public static void generateTheMenu() {
System.setProperty("sun.java2d.cmm", "sun.java2d.cmm.kcms.KcmsServiceProvider");
StatusBar.createStatusBar();
SwingWorker<String, String> worker = new SwingWorker<String, String>() {
@Override
protected String doInBackground() throws Exception {
String rawMenuOutput = "Restaurant Menu";
rawMenuOutput = rawMenuOutput + "Test line";
String[] menuOtpArr = new String[3];
try {
TimeUnit.SECONDS.sleep(2);
publish("1234567890123456789012345678901234567890");
TimeUnit.SECONDS.sleep(2);
publish("This is a test");
TimeUnit.SECONDS.sleep(2);
publish("More testing");
TimeUnit.SECONDS.sleep(2);
publish("Still testing");
TimeUnit.SECONDS.sleep(2);
} catch (Exception e) {
}
for (int i = 0; i < menuOtpArr.length; i++) {
rawMenuOutput = rawMenuOutput + "\n\n" + menuOtpArr[i];
}
return rawMenuOutput;
}
@Override
protected void done() {
StatusBar.closeStatusBar();
}
@Override
protected void process(List<String> chunks) {
StatusBar.setStatusBar(chunks.get(chunks.size() - 1));
}
};
worker.addPropertyChangeListener(new PropertyChangeListener() {
@Override
public void propertyChange(PropertyChangeEvent evt) {
if (worker.getState() == SwingWorker.StateValue.DONE) {
try {
String result = worker.get();
System.out.println(result);
StatusBar.closeStatusBar();
} catch (InterruptedException | ExecutionException ex) {
ex.printStackTrace();
}
}
}
});
worker.execute();
}
public static class StatusBar {
private static JLabel statusLabel = new JLabel("Starting");
private static JFrame statusFrame = new JFrame("Generation Status");
public static void createStatusBar() {
Font menuFont = new Font(Font.MONOSPACED, Font.BOLD, 20);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
statusFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
statusFrame.setSize(700, 100);
JPanel p = new JPanel();
p.setBackground(Color.RED);
// p.setPreferredSize(new Dimension(100, 100));
statusLabel.setFont(menuFont);
p.add(statusLabel);
statusFrame.add(p, BorderLayout.CENTER);
statusFrame.setLocationRelativeTo(null);
statusFrame.setVisible(true);
}
public static void setStatusBar(String statusText) {
statusLabel.setText(statusText);
}
public static void closeStatusBar() {
statusFrame.dispose();
}
}
}
观察...
-
static不是您的朋友，尤其是在这种情况下.您确实非常确实需要学习没有它的生活. -
setLayout(null)对您没有任何帮助，特别是从长远来看.请抽空阅读在容器内布置组件并开始正确使用布局管理器，它们看起来可能很复杂"，但是它们可以帮助您避免脱发. - 尽可能避免使用
setPreferred/Minimum/MaximumSize，您正在剥夺提供有用的渲染提示的功能，该提示可能会在平台和渲染管道之间发生变化 staticis not your friend, especially in cases like this. You really, really, really need to learn to live without it.setLayout(null)is not doing you any favours, especially in the long run. Take the time to go through Laying Out Components Within a Container and start making proper use of layout managers, they might seem "complicated", but they will save you from a lot of hair loss- Avoid using
setPreferred/Minimum/MaximumSizewhere ever possible, you are robing the component of the ability to provide useful rendering hints which may change across platforms and rendering pipelines - 您想解耦代码.这样可以更轻松地更改代码的某些部分，而不会影响其他部分
- 您希望能够编码到接口，而不是实现".这与第一条评论并驾齐驱.基本上，您想尽可能多地隐藏"实现细节-这样做的原因很多，但这可以使您的代码精益求精，可以使后续操作更易于理解，并可以阻止一部分代码访问其真正拥有的另一部分没有责任这样做(字符串生成确实负责更新状态栏吗?恕我直言-并非如此)
- 还有大量的设计模式可用来简化解决问题的过程.我已经提到过生产/消费"的概念，但这只是一个
- You want to decouple your code. This makes it easier to change certain parts of the code without affecting the other parts
- You want to be able to "code to interface, not implementation". This goes hand in hand with the first comment. Basically, you want to "hide" the implementation details as much as possible - lots of different reasons for it, but it helps keep your code lean, helps make the follow more understandable and stops one part of the code from accessing another it really has no responsibility to do so (is the string generation really responsible for updating the status bar? IMHO - not really)
- There is also a swagger of design patterns available to make solving issues easier. I've already mentioned the concept of "produce/consumer", but this is just one
- The Event Dispatch Thread
- Java Event-Dispatching Thread explanation
- Swing threading and the event-dispatch thread
Observations...
只是一个快速跟进的问题，done和addPropertyListener有什么区别?有没有?两者都使用是多余的吗?
Just a quick follow up question, what is the difference between done and addPropertyListener ? Is there any? Isnt it redundant to use both?
这里的示例非常基本，对我来说，我已经使用done来处理SwingWorker知道"需要完成的工作，但是它不知道如何处理结果.
The example here is pretty basic, for me I've used done to handle what the SwingWorker "knows" needs to be done, it doesn't however, know what is to be done with the result.
我已经使用PropertyChangeListener来处理该问题-重点-这是一个示例.
I've used the PropertyChangeListener to deal with that instead - the point - it's an example.
我还注意到，我不需要实际发布，就像调用StatusBar.setStatusBar(");一样.也可以.是否有必要使用发布?
And I also noticed, that I dont need to actually publish, as calling StatusBar.setStatusBar(""); works as well. Is it necessary to use publish?
一言以蔽之. Swing不是线程安全的，直接调用StatusBar.setStatusBar("")可能会导致一些奇怪和意外的结果. publish将调用推送到事件调度线程中，从而可以安全地从内部更新UI.
In a word YES. Swing is NOT thread safe, calling StatusBar.setStatusBar("") directly can lead to some weird and unexpected results. publish pushes the call into the Event Dispatching Thread, making it safe to update the UI from within.
我有用于生成要设置为另一个类(而不是generateTheMenu)中的StatusBar Title的字符串的代码，因此对我来说，简单地调用.setStatusBar更为方便.我拥有的并非最少的代码实际上是这样的
I have the code for generating the String I want to set as the StatusBar Title in another class, not in the generateTheMenu, therefore it is more convenient for me to simply call .setStatusBar. The not minimal code I have is actually something like this
这是诸如interface之类的东西派上用场的地方.您通过字符串"生成类可以"返回结果文本，或者您可以传递对interface实现的引用，该实现用于显示"它.这样，您的SwingWorker可以充当String的使用者，并将其通过publish方法传递.
This is where things like interfaces come in really handy. You "string" generating class "could" either return the resulting text OR you could pass a reference to a interface implementation which is used to "display" it. This way, your SwingWorker could act as a consumer for the String and pass it through the publish method.
有很多非常重要的概念需要理解.
There are a number of really important concepts to understand.
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