在java中的组合框上添加项目运行时 [英] add items runtime on combobox in java

问题描述

我在 Swing 中创建了一个 comboBox，我想在另一个函数中添加项目.但问题是调用该函数后项目不显示:

I have created a comboBox in Swing and I want to add items on it in another function. But the problem is that items are not displaying after calling that function:

public void addItems()
{
    combo.addItem("");
    // i want to add items here when this function is being called
    // but those items are not displaying after calling this function
    // i m calling this function on button click
}

推荐答案

在这个 SSCCE 中为我工作:

Works for me in this SSCCE:

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

import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import javax.swing.UnsupportedLookAndFeelException;

public class TestComboBox {

    private int count = 0;

    protected void initUI() {
        final JFrame frame = new JFrame(TestComboBox.class.getSimpleName());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final JComboBox comboBox = new JComboBox(new Object[] { "Something", "Stuff", "Beep" });
        JButton add = new JButton("Add item");
        add.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                comboBox.addItem("Item-" + count++);
            }
        });
        frame.add(comboBox);
        frame.add(add, BorderLayout.SOUTH);
        frame.pack();
        frame.setBounds(50, 50, 300, frame.getHeight());
        frame.setVisible(true);
    }

    public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException,
            UnsupportedLookAndFeelException {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new TestComboBox().initUI();
            }
        });
    }
}

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