java - JTabpan 拆分按钮

Question

根据https://docs.oracle.com/javase/tutorial/uiswing/components/tabbedpane.html我可以将自定义组件添加到 jtabpane，我尝试向选项卡添加一个组合框，这样选项卡中就会有一个向下的箭头，可以从选择中进行选择，就像带有拆分按钮的 Jtabpane 一样。

在我的示例中，我尝试使用关闭按钮修改现有的选项卡 Pane ，但它不起作用。谁能指出我正确的方向？

import java.awt.FlowLayout;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JComboBox;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.plaf.ComboBoxUI;

public class DropdownPaneComponent extends JPanel {
    String[] calcStrings = { "BMI", "BMR", "BFP", "Weight Loss"};
    private JTabbedPane pane;

    public DropdownPaneComponent(JTabbedPane pane) {
        //unset default FlowLayout' gaps
        super(new FlowLayout(FlowLayout.LEFT, 0, 0));
        if (pane == null) {
            throw new NullPointerException("TabbedPane is null");
        }
        this.pane = pane;
        setOpaque(false);

        //make JLabel read titles from JTabbedPane
        JLabel label = new JLabel() {
            public String getText() {
                int i = pane.indexOfTabComponent(DropdownPaneComponent.this);
                if (i != -1) {
                    return pane.getTitleAt(i);
                }
                return null;
            }
        };

        add(label);
        //add more space between the label and the button
        label.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 5));
        //tab button
        JComboBox jcbCalcs = new TabButton();
        add(jcbCalcs);
        //add more space to the top of the component
        setBorder(BorderFactory.createEmptyBorder(2, 0, 0, 0));
    }

    private class TabButton extends JComboBox  {
        public TabButton() {
            super(calcStrings);
             setToolTipText("close this tab");
             //Make the button looks the same for all Laf's

             //Make it transparent

             //No need to be focusable
             setFocusable(false);
             setBorder(BorderFactory.createEtchedBorder());


        }
    }
 }

jframe

import java.awt.EventQueue;

import javax.swing.JFrame;
import javax.swing.JTabbedPane;
import java.awt.BorderLayout;
import javax.swing.JPanel;
import javax.swing.JMenuBar;
import javax.swing.JMenu;
import javax.swing.JComboBox;
import javax.swing.JButton;

public class FatBlaster {

    private JFrame frmFatBlasterPrototype;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    FatBlaster window = new FatBlaster();
                    window.frmFatBlasterPrototype.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public FatBlaster() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frmFatBlasterPrototype = new JFrame();
        frmFatBlasterPrototype.setTitle("Fat Blaster Prototype");
        frmFatBlasterPrototype.setBounds(100, 100, 450, 300);
        frmFatBlasterPrototype.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JTabbedPane tabbedPane = new JTabbedPane(JTabbedPane.TOP);
        frmFatBlasterPrototype.getContentPane().add(tabbedPane, BorderLayout.CENTER);       

        JPanel pnlCalculation = new JPanel();
        tabbedPane.addTab("Calculations", null, pnlCalculation, null);
        tabbedPane.setComponentAt(0, new DropdownPaneComponent(tabbedPane));

        JPanel pnlFoodDiary = new JPanel();
        tabbedPane.addTab("Food Diary", null, pnlFoodDiary, null);

        JMenuBar menuBar = new JMenuBar();
        frmFatBlasterPrototype.setJMenuBar(menuBar);

        JMenu mnNewMenu = new JMenu("File");
        menuBar.add(mnNewMenu);

        JMenu mnNewMenu_1 = new JMenu("View");
        menuBar.add(mnNewMenu_1);
    }

}

Answer 1

From my example i have tried to modify the existing tab pane with a close button , however it does not work. anyone can point me in the right direction?

在教程的 ButtonTabComponent 类中，我进行了以下更改:

//JButton button = new TabButton();
//add(button);
String[] calcStrings = { "BMI", "BMR", "BFP", "Weight Loss"};
add( new JComboBox(calcStrings) );

并且组合框按预期显示在选项卡上。

所以，我建议你:

1. 从教程中的工作示例开始
2. 进行与上述相同的更改以证明您可以使用组合框
3. 从教程中删除一些不必要的代码并重新测试。
4. 然后，当它再次停止工作时，您就知道您所做的更改导致了问题。