java如何使JCombobox具有更改其他JCombobox上的项的函数

Question

我的转换器程序中有3个JCombobox，一个用于类别，两个用于选择要执行的功能；我想让程序做的是，当用户在一个JCombobox中选择一个类别时，两个JCombobox将自动更改与所选类别相关的内容（请帮助我使用JCombobox更改项的功能，当一个选中其他更改值时）

Answer 1

尝试使用itemStateChanged（java.awt.event.ItemEvent evt）

Answer 2

使用ItemListener而不是ActionListener表示JComboBox，将两个Listener放在一起example about ActionListener with ItemListener for two JComboBoxes

Answer 3

正如JB Nizet所说，这里有一个简短的例子：

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.DefaultComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;


public class ConnectedComboBoxDemo extends JFrame implements ActionListener {

    private static final long serialVersionUID = 6108579736224814080L;

    private JPanel panel;
    private JComboBox combo1;
    private JComboBox combo2;

    public ConnectedComboBoxDemo() {
        panel = new JPanel();
        String[] combo1Item = new String[]{"val1", "val2", "val3"};
        combo1 = new JComboBox(combo1Item);
        combo1.addActionListener(this);

        String[] combo2Item = new String[]{"val11", "val12", "val13"};
        combo2 = new JComboBox(combo2Item);

        panel.setLayout(new BorderLayout());
        panel.add(combo1, BorderLayout.WEST);
        panel.add(combo2, BorderLayout.EAST);

        setContentPane(panel);
        pack();
        setVisible(true);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String selectedValue = combo1.getSelectedItem().toString();
        String[] combo2Item = null;

        DefaultComboBoxModel model = (DefaultComboBoxModel) combo2.getModel();      
        model.removeAllElements();

        if(selectedValue.equals("val1")){
            combo2Item = new String[]{"val11", "val12", "val13"};
        } else if(selectedValue.equals("val2")){
            combo2Item = new String[]{"val21", "val22", "val23"};
        } else if(selectedValue.equals("val3")){
            combo2Item = new String[]{"val31", "val32", "val33"};
        }

        for(String val : combo2Item){
            model.addElement(val);
        }
    }   

    public static void main(String... args){
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new ConnectedComboBoxDemo();
            }
        });
    }
}

希望这对你有帮助

Answer 4

只需在第一个组合框中添加一个ActionListener，然后在action listener的actionPerformed方法中，在第一个组合框中获取所选的值，并更改第二个组合框显示的值

阅读Swing tutorial about combo boxes