选项卡内的面板未显示答案

【问题标题】：Panel inside tab not displayed选项卡内的面板未显示
【发布时间】：2019-08-20 17:48:45
【问题描述】：

我正在尝试使用 IntelliJ GUI 表单创建 UI。我创建了一个扩展 JFrame 的类，并且只包含 JTabbedPane 和 2 个选项卡，每个选项卡都有一个 JPanel。然后是 2 个扩展 JPanel 的其他类。但是，启动时没有面板显示。

我尝试过使面板无效、重绘和重新验证

//main class
import javax.swing.*;

public class jumpManMain {
    public static void main (String[] args) {
        SwingUtilities.invokeLater(() -> {
            final JFrame frame =  new frmTabs();
        });
    }
}

// tabbedpanel class
public class frmTabs extends JFrame implements constants{
    private JTabbedPane tabbedPane;
    private JPanel panelTab1;
    private JPanel panelTab2;

    public frmTabs()
    {
        setContentPane(tabbedPane);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(FORM_LEFT, FORM_TOP, FORM_WIDTH, FORM_HEIGHT);
        panelTab1 = new panel1();
        panelTab2 = new panel2();
        pack();
        setVisible(true);
        setSize(FORM_WIDTH,FORM_HEIGHT);


        ChangeListener changeListener = new ChangeListener() {
            public void stateChanged(ChangeEvent changeEvent) {
                JTabbedPane sourceTabbedPane = (JTabbedPane) changeEvent.getSource();
                int index = sourceTabbedPane.getSelectedIndex();
                System.out.println("Tab changed to: " + sourceTabbedPane.getTitleAt(index));
                panelTab1.revalidate();
                panelTab1.repaint();
                panelTab2.revalidate();
                panelTab2.repaint();
            }
        };
        tabbedPane.addChangeListener(changeListener);
    }

}

//tabs form generated by IntelliJ
<?xml version="1.0" encoding="UTF-8"?>
<form xmlns="http://www.intellij.com/uidesigner/form/" version="1" bind-to-class="frmTabs">
  <tabbedpane id="78766" binding="tabbedPane">
    <constraints>
      <xy x="20" y="20" width="900" height="560"/>
    </constraints>
    <properties>
      <minimumSize width="900" height="560"/>
      <preferredSize width="900" height="560"/>
    </properties>
    <border type="none"/>
    <children>
      <grid id="35c5e" binding="panelTab1" layout-manager="GridLayoutManager" row-count="1" column-count="1" same-size-horizontally="false" same-size-vertically="false" hgap="-1" vgap="-1">
        <margin top="0" left="0" bottom="0" right="0"/>
        <constraints>
          <tabbedpane title="Jumps arrived"/>
        </constraints>
        <properties>
          <maximumSize width="1000" height="1000"/>
          <minimumSize width="900" height="560"/>
          <preferredSize width="900" height="560"/>
        </properties>
        <border type="none"/>
        <children/>
      </grid>
      <grid id="4323" binding="panelTab2" layout-manager="GridLayoutManager" row-count="1" column-count="1" same-size-horizontally="false" same-size-vertically="false" hgap="-1" vgap="-1">
        <margin top="0" left="0" bottom="0" right="0"/>
        <constraints>
          <tabbedpane title="Jumps created"/>
        </constraints>
        <properties>
          <maximumSize width="1000" height="1000"/>
          <minimumSize width="900" height="560"/>
          <preferredSize width="900" height="560"/>
        </properties>
        <border type="none"/>
        <children/>
      </grid>
    </children>
  </tabbedpane>
</form>

//panel1 XML
<?xml version="1.0" encoding="UTF-8"?>
<form xmlns="http://www.intellij.com/uidesigner/form/" version="1" bind-to-class="panel1">
  <grid id="27dc6" binding="panelMain" layout-manager="GridLayoutManager" row-count="6" column-count="5" same-size-horizontally="false" same-size-vertically="false" hgap="-1" vgap="-1">
    <margin top="5" left="5" bottom="5" right="5"/>
    <constraints>
      <xy x="21" y="20" width="900" height="560"/>
    </constraints>
    <properties>
      <minimumSize width="900" height="560"/>
      <preferredSize width="900" height="560"/>
      <requestFocusEnabled value="true"/>
    </properties>
    <border type="bevel-raised" title="Jump Ticket Manager">
      <font name="Arial Black" style="1"/>
      <title-color color="-4451918"/>
    </border>
    <children>
....
    </children>
  </grid>
</form>
...

【问题讨论】：

我对 IntelliJ 表单设计器一无所知。我建议您学习如何手动创建表单，以便您完全控制。这样，如果您需要切换到不同的 IDE，代码也可以工作。阅读 How to Use Tabbed Panes 上的 Swing 教程中的部分，以获取帮助您入门的示例。
您已经初始化了两个面板，但您忘记将它们添加到您的 TabbedPanel..
旁注：见Java Naming Conventions和A Visual Guide to Layout Managers

标签： java swing jframe jpanel jtabbedpane

【解决方案1】：

您缺少以下步骤

1.JTabbedPane 初始化

  tabbedPane = new JTabbedPane();

将面板添加到您的 JTabbedPane

tabbedPane.add(panelTab1);
tabbedPane.add(panelTab2);

因此您的最终代码将如下所示

 public class Main {
     public static void main(String[] args) {
         SwingUtilities.invokeLater(() -> {
            final JFrame frame =  new frmTabs();
       });
   }
 }

class frmTabs extends JFrame implements constants{
private JTabbedPane tabbedPane;
private JPanel panelTab1;
private JPanel panelTab2;

public frmTabs()
{
    tabbedPane = new JTabbedPane();
    setContentPane(tabbedPane);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(FORM_LEFT, FORM_TOP, FORM_WIDTH, FORM_HEIGHT);
    panelTab1 = new JPanel();
    panelTab2 = new JPanel();
    panelTab1.setName("first Tab");   //To add titles to your tabs
    panelTab2.setName("Second Tab");  //to add titles to your tabs
    tabbedPane.add(panelTab1);
    tabbedPane.add(panelTab2);
    pack();
    setVisible(true);
    setSize(FORM_WIDTH,FORM_HEIGHT);


    ChangeListener changeListener = new ChangeListener() {
        public void stateChanged(ChangeEvent changeEvent) {
            JTabbedPane sourceTabbedPane = (JTabbedPane) changeEvent.getSource();
            int index = sourceTabbedPane.getSelectedIndex();
            System.out.println("Tab changed to: " + sourceTabbedPane.getTitleAt(index));
            panelTab1.revalidate();
            panelTab1.repaint();
            panelTab2.revalidate();
            panelTab2.repaint();
        }
    };
    tabbedPane.addChangeListener(changeListener);
    }
  }

*NB 以下几行将为您的选项卡式面板添加标题

  panelTab1.setName("first Tab");  
  panelTab2.setName("Second Tab");

输出

  Tab changed to: Second Tab
  Tab changed to: first Tab

  Process finished with exit code 0

【讨论】：

我试过了，但没有用。我只用java panelTab1 = new panel1(); panelTab2 = new panel2(); 替换了新面板，但面板内的对象没有显示。 \n 除此之外，当java tabbedPane = new JTabbedPane(); IntelliJ 给我一个警告分配给 UI 绑定字段将覆盖字段生成的 UI 设计器表单。此类分配将导致 UI Designer 为此类字段生成的组件设置代码被忽略。
Java panelTab1 = new panel1(); 是初始化阶段（步骤 1）。要显示此窗格，您需要将其添加到选项卡式窗格，因此 tabbedPane.add(panelTab1); 。你错过了tabbedPane.add(panelTab1);
使用 IntelliJ UI Designer 无需添加选项卡或窗格。它们由 IntelliJ 自动初始化。这就是我收到警告的原因，
我添加了由 IntelliJ UI Designer 生成的 XML。一切都运行良好，但都没有显示。选项卡内的窗格是否有“特殊”布局？

【解决方案2】：

有效地使用 IntelliJ GUI，解决方案是这样的：

1) 创建主类

public class jManagerMainUI extends JFrame {
private JPanel panelTab1;
private JPanel panelTab2;
private JTabbedPane tabbedPane;

public jManagerMainUI(String param) {
    setContentPane(tabbedPane);
    tabbedPane.setBounds(FORM_LEFT, FORM_TOP, FORM_WIDTH, FORM_HEIGHT);
    setDefaultCloseOperation(3);
    setBounds(FORM_LEFT, FORM_TOP, FORM_WIDTH, FORM_HEIGHT);
    tabbedPane.setComponentAt(0,new jA(param).getPanel());
    tabbedPane.setComponentAt(1,new jC(param).getPanel());
    pack();
    setVisible(true);
    setSize(FORM_WIDTH, FORM_HEIGHT);
}
}

2) 为每个选项卡创建一个类，该类将返回对面板的引用

public class jA extends JFrame {
    private JPanel panelA;
    //Tab A
    private JButton btAddA;

    public JPanel getPanel() {
        return panelA;
    }
...

【讨论】：