java - 如何在 Swing 中将 Label 设置为 Display，将 value 设置为 JCombobox 中的值？

Question

我的代码动态创建 Jcombobox 并填充查询结果中的项目。此查询返回一个包含标签和值的对象。我想在调用 combo.getSelectedItem() 时显示标签并返回值。我看到了这个Example在搜索时，但我没有得到这个想法。

JComboBox<String> jComboBox=new JComboBox<String>();

if(dataSourceAttributeObjs!=null && dataSourceAttributeObjs.size()>0)
{
    jComboBox.addItem("Select");
    for(DataSourceAttributeObj dataSourceAttributeObj:dataSourceAttributeObjs)
    {
        jComboBox.addItem(dataSourceAttributeObj.getLabel());
    }
}

Answer 1

您提到的示例( Set Value and Label to JComboBox )描述了为组合框定义自定义渲染器的可能性，这似乎是您的情况的正确方法。

nachokk的回答在一段代码中:

import java.awt.*;
import java.util.*;
import javax.swing.*;

public class CustomComboBoxRenderer {
    public static void main(final String[] arguments) {
        new CustomComboBoxRenderer().launchGui();
    }

    private void launchGui() {
        final JFrame frame = new JFrame("Stack Overflow: custom combo box renderer");
        frame.setBounds(100, 100, 800, 600);
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        final JComboBox<Concept> comboBox = getComboBox();
        final JLabel label = new JLabel("Please make a selection...");

        comboBox.addActionListener(actionEvent -> {
            final Object selectedItem = comboBox.getSelectedItem();
            if (selectedItem instanceof Concept)
                label.setText(((Concept) selectedItem).getValue());
        });

        final JPanel panel = new JPanel(new BorderLayout());
        panel.add(comboBox, BorderLayout.NORTH);
        panel.add(label, BorderLayout.CENTER);
        frame.getContentPane().add(panel);

        frame.setVisible(true);
    }

    private JComboBox<Concept> getComboBox() {
        final List<Concept> concepts = Arrays.asList(new Concept("label 1", "value 1"),
                                                     new Concept("label 2", "value 2"),
                                                     new Concept("label 3", "value 3"));

        final JComboBox<Concept> comboBox = new JComboBox<>(new Vector<>(concepts));

        comboBox.setRenderer(new DefaultListCellRenderer() {
            @Override
            public Component getListCellRendererComponent(final JList<?> list,
                                                          final Object value,
                                                          final int index,
                                                          final boolean isSelected,
                                                          final boolean cellHasFocus) {
                super.getListCellRendererComponent(list, value, index, isSelected,
                                                   cellHasFocus);
                if (value instanceof Concept)
                    setText(((Concept) value).getLabel());

                return this;
            }
        });

        return comboBox;
    }
}

Concept 类可能如下所示:

public class Concept {
    private final String label;
    private final String value;

    public Concept(String label, String value) {
        this.label = label;
        this.value = value;
    }

    public String getLabel() {
        return label;
    }

    public String getValue() {
        return value;
    }
}