blocks|key|4363676|text|示例是Jpanel。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4363677|Sample扩展了JPanel意味着你继承了JPanel。|4363678|去掉JPanel+p和你所有的“p”|4363679|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

Sample is the Jpanel.

Sample extends JPanel means you inherit from JPanel.

just drop JPanel p and all your "p."s

blocks|key|2572224|text|您忘记将面板p添加到示例中。要么在最后使用add(p)，要么直接删除面板p，因为您的示例类正在扩展JPanel。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2572225|选项1：|2572226|++++JPanel+p+=+new+JPanel();

++++JLabel+lab1+=+new+JLabel("User+Name",+JLabel.LEFT);
++++p.setLayout(new+FlowLayout());+
++++p.add(lab1+=+new+JLabel("add+JLabel"));
++++add(p);|code-block|syntax|javascript|2572227|选项2：|2572228|++++JLabel+lab1+=+new+JLabel("User+Name",+JLabel.LEFT);
++++setLayout(new+FlowLayout());+
++++add(lab1+=+new+JLabel("add+JLabel"));|2572229|2572230|另外，为什么要覆盖JLabel的初始化？在您的代码中，JLable将始终保持值"add+JLabel“。如果你想看到“用户名”，那么使用这个add(lab1);而不是add(lab1+=+new+JLabel("add+JLabel"));。|2572231|也许你只需要这样：|2572232|++++JLabel+lab1+=+new+JLabel("User+Name",+JLabel.LEFT);
++++setLayout(new+FlowLayout());+
++++add(lab1);|2572233|2572234|另外，构造函数不能有返回类型，所以从构造函数中删除void。|2572235|entityMap^0|6|1|L|6|10|1|0|0|0|0|0|0|1Y|A|2B|11|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@$9|13|A|14|B|C]|$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|1A|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|1B|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|1C|8|@]|D|@]|E|$K|L]]|$1|Q|3|-4|5|6|7|1D|8|@]|D|@]|E|$]]|$1|R|3|S|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|T|3|U|5|6|7|1J|8|@]|D|@]|E|$]]|$1|V|3|W|5|J|7|1K|8|@]|D|@]|E|$K|L]]|$1|X|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]|$1|Y|3|Z|5|6|7|1M|8|@]|D|@]|E|$]]|$1|10|3|-4|5|6|7|1N|8|@]|D|@]|E|$]]]|11|$]]

You are forgot to add panel <code>p</code> to sample. Either use <code>add(p)</code> at the end or just remove panel <code>p</code> cause your sample class is extending JPanel.

Option 1:

<pre><code> JPanel p = new JPanel();

 JLabel lab1 = new JLabel("User Name", JLabel.LEFT);
 p.setLayout(new FlowLayout()); 
 p.add(lab1 = new JLabel("add JLabel"));
 add(p);
</code></pre>

option 2:

<pre><code> JLabel lab1 = new JLabel("User Name", JLabel.LEFT);
 setLayout(new FlowLayout()); 
 add(lab1 = new JLabel("add JLabel"));
</code></pre>

<hr>

Also why are you overriding initialization of JLabel? In your code JLable will always hold value "add JLabel". If you want to see "User Name" then use this <code>add(lab1);</code> instead of <code>add(lab1 = new JLabel("add JLabel"));</code>.

May be you just require this:

<pre><code> JLabel lab1 = new JLabel("User Name", JLabel.LEFT);
 setLayout(new FlowLayout()); 
 add(lab1);
</code></pre>

<hr>

Also constructor can not have return type so remove void from your constructor.

blocks|key|669470|text|您正在使用的构造函数不是正确的构造函数。java构造函数没有返回类型，并且void是额外的。当您在main方法中调用new+Sample()时，它实际上并没有调用您的方法，而是默认存在的默认构造函数。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|669471|试着这样..。|669472|public+Sample()+{
++++JPanel+p+=+new+JPanel();

++++JLabel+lab1+=+new+JLabel("User+Name",+JLabel.LEFT);
++++p.setLayout(new+FlowLayout());
++++p.add(lab1+=+new+JLabel("add+JLabel"));
}|code-block|syntax|javascript|669473|此外，您还需要按照@Harry+Joy建议的方式添加add(p);语句，否则面板仍然不会添加。|669474|entityMap^0|11|4|0|0|0|Q|7|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@$9|W|A|X|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

The constructor that you are using is not a proper constructor .. A java constructor does not have a return type and the <code>void</code> is extra. When in the main method you are calling new Sample() it is not actually calling your method but the default constructor that exists by default.

Try like this ..

<pre><code>public Sample() {
 JPanel p = new JPanel();

 JLabel lab1 = new JLabel("User Name", JLabel.LEFT);
 p.setLayout(new FlowLayout());
 p.add(lab1 = new JLabel("add JLabel"));
}
</code></pre>

also you need to do what @Harry Joy suggested to add the <code>add(p);</code> statement otherwise the panel is still not added.

blocks|key|2572352|text|请注意注释。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2572353|import+java.awt.*;
import+javax.swing.*;

public+class+Sample+extends+JPanel+{

++++public+Sample()+{
++++++++//+set+the+layout+in+the+constructor
++++++++super(new+FlowLayout(FlowLayout.LEADING));

++++++++//+best+not+to+set+size+OR+preferred+size!
++++++++setPreferredSize(+new+Dimension(200,200)+);

++++++++JLabel+lab1+=+new+JLabel("User+Name");
++++++++add(lab1);
++++}

++++public+static+void+main(String[]+args)+{
++++++++//+construct+the+GUI+on+the+EDT
++++++++SwingUtilities.invokeLater(+new+Runnable()+{
++++++++++++public+void+run()+{
++++++++++++++++JFrame+frame+=+new+JFrame("User+Details");
++++++++++++++++frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

++++++++++++++++frame.getContentPane().add(new+Sample());
++++++++++++++++//+important!
++++++++++++++++frame.pack();

++++++++++++++++frame.setVisible(true);
++++++++++++}
++++++++});
++++}
}|code-block|syntax|javascript|2572354|2572355|还请注意，除非添加自定义功能，否则通常不认为扩展组件是一个好主意。这将意味着(例如)为Sample面板定义新方法(如果我正确地猜测您要使用该代码的位置，则最好将其标记为UserDetails或UserDetailsContainer+)。或者它可能是一个Login组件。|offset|length|style|CODE|2572356|entityMap^0|0|0|0|17|6|2C|B|2O|K|3J|5|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|S|8|@$J|T|K|U|L|M]|$J|V|K|W|L|M]|$J|X|K|Y|L|M]|$J|Z|K|10|L|M]]|9|@]|A|$]]|$1|N|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|O|$]]

Note the comments.

<pre><code>import java.awt.*;
import javax.swing.*;

public class Sample extends JPanel {

 public Sample() {
 // set the layout in the constructor
 super(new FlowLayout(FlowLayout.LEADING));

 // best not to set size OR preferred size!
 setPreferredSize( new Dimension(200,200) );

 JLabel lab1 = new JLabel("User Name");
 add(lab1);
 }

 public static void main(String[] args) {
 // construct the GUI on the EDT
 SwingUtilities.invokeLater( new Runnable() {
 public void run() {
 JFrame frame = new JFrame("User Details");
 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

 frame.getContentPane().add(new Sample());
 // important!
 frame.pack();

 frame.setVisible(true);
 }
 });
 }
}
</code></pre>

<hr>

Note also, that it is generally not considered a good idea to extend a component unless adding custom functionality. That would mean (for example) defining new methods for the <code>Sample</code> panel (Which might better be labelled a <code>UserDetails</code> or <code>UserDetailsContainer</code> if I guess correctly where you are going with that code..). Or it might be a <code>Login</code> component..

blocks|key|2572399|text|@SuppressWarning(“serial”)公共类MyGui扩展了JFrame{|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2572400|private+MyContentPane+myContentPane+=+new+MyContentPane();+

public+MyGui(){
++++super("title");
++++this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
++++this.setContentPane(myContentPane);

++++this.createMenu();

++++this.pack();
++++this.setVisible(true);++++++
}

private+void+createMenu(){
++++JMenuBar+myMenuBar+=+new+JMenuBar();

++++JMenu+xMenu+=+new+JMenu("x");
++++JMenu+x+=+new+JMenu("x");

++++JMenuItem+xItem+=+new+JMenuItem("letter");

++++JMenuItem+exitItem+=+new+JMenuItem("exit");

++++xItem.addActionListener(new+ActionListener(){
++++++++public+void+actionPerformed(ActionEvent+arg0)+{
++++++++++++myContentPane.xPanel();
++++++++}
++++});
++++xItem.addActionListener(new+ActionListener(){
++++++++public+void+actionPerformed(ActionEvent+arg0)+{
++++++++++++myContentPane.setxPanel();
++++++++}
++++});

++++exitItem.addActionListener(new+ActionListener(){
++++++++public+void+actionPerformed(ActionEvent+e)+{
++++++++++++System.exit(0);
++++++++}
++++});

++++displayMenu.add(letterItem);
++++displayMenu.add(colorItem);

++++fileMenu.add(exitItem);

++++myMenuBar.add(displayMenu);
++++myMenuBar.add(fileMenu);

++++this.setJMenuBar(myMenuBar);
}|code-block|syntax|javascript|2572401|}|2572402|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

@SuppressWarnings("serial")
public class MyGui extends JFrame{

<pre><code>private MyContentPane myContentPane = new MyContentPane(); 

public MyGui(){
 super("title");
 this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 this.setContentPane(myContentPane);

 this.createMenu();

 this.pack();
 this.setVisible(true); 
}

private void createMenu(){
 JMenuBar myMenuBar = new JMenuBar();

 JMenu xMenu = new JMenu("x");
 JMenu x = new JMenu("x");

 JMenuItem xItem = new JMenuItem("letter");

 JMenuItem exitItem = new JMenuItem("exit");

 xItem.addActionListener(new ActionListener(){
 public void actionPerformed(ActionEvent arg0) {
 myContentPane.xPanel();
 }
 });
 xItem.addActionListener(new ActionListener(){
 public void actionPerformed(ActionEvent arg0) {
 myContentPane.setxPanel();
 }
 });

 exitItem.addActionListener(new ActionListener(){
 public void actionPerformed(ActionEvent e) {
 System.exit(0);
 }
 });

 displayMenu.add(letterItem);
 displayMenu.add(colorItem);

 fileMenu.add(exitItem);

 myMenuBar.add(displayMenu);
 myMenuBar.add(fileMenu);

 this.setJMenuBar(myMenuBar);
}
</code></pre>

}

I have simple problem as I am not much familiar with Java GUI. I am trying to make visible the JLable on the below code as I find it hard to understand the concept. But still label is not visible but the frame do open on run time.

<pre><code>public class Sample extends JPanel {

 public void Sample() {
 JPanel p = new JPanel();

 JLabel lab1 = new JLabel("User Name", JLabel.LEFT);
 p.setLayout(new FlowLayout());
 p.add(lab1 = new JLabel("add JLabel"));
 }

 public static void main(String[] args) {

 JFrame frame = new JFrame();
 frame.getContentPane().add(new Sample());

 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 frame.setSize(200, 200);
 frame.setVisible(true);
 }
}
</code></pre>

Simple Adding a JLabel to JPanel

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我有一个简单的问题，因为我不太熟悉Java GUI。我试图让JLable在下面的代码中可见，因为我发现很难理解这个概念。但仍然看不到标签，但框架确实在运行时打开。public class Sample extends JPanel {    public void Sample() {        JPanel p ...

问简单地向JPanel添加JLabel
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问简单地向JPanel添加JLabelEN