求助：JComboBox下拉列表 - 下拉异常出错

Question

JAVAJComboBox图形界面 下拉列表

Answer 1

jComboBox1=new JComboBox<String>(fruit);
这个别指定成string,试试。

Answer 2

你用的jdk版本是？
我记得JComboBox不支持泛型吧；

Answer 3

jComboBox1=new JComboBox(fruit);
这么写也是一样的错啊。。
JDK版本是1.8

Answer 4

Container container = this.getLayeredPane();
//  没有遇到过这种情况，不过看这句很奇怪，因为很少用到LayeredPane 
        container.setLayout(new BorderLayout());
        container.add(combop, BorderLayout.NORTH);
        container.add(tab, BorderLayout.CENTER);
于是改成使用ContentPane来添加组件，并且修改利用JPanel来添加JLabel        p1.add(
                new JLabel("<选择需要转化的Excel文档>", SwingConstants.CENTER),
                BorderLayout.CENTER);        jwordpath = new JTextField(30);
        jfilepath = new JButton("选择需要读取的Excel文档");        p1.add(new JLabel("选择输出文档的存放路径", SwingConstants.CENTER),
                BorderLayout.CENTER);好了，没有异常了，可能是由于布局添加太混乱，导致的。swing顶层容器的布局层结构是   JRootPane -》JLayeredPane（其中包含JMenuBar和ContentPane）-》GlassPane（高级渲染用），一般使用JMenuBar和Content Pane（内容面板）就够了，高级的我也说不上来，也是刚学的新手在lz的基础上，修改的代码（99%没改），只是针对错误的地方改了一下而已，建议全重构布局。import java.awt.BorderLayout;
import java.awt.*;
import java.awt.GridLayout;
import java.awt.event.*;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;import javax.swing.BorderFactory;
import javax.swing.ComboBoxModel;
import javax.swing.JButton;
import javax.swing.JComboBox;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.filechooser.FileFilter;
import javax.swing.filechooser.FileNameExtensionFilter;//import javax.swing.JComboBoxDemo.Model;//import com.hanfeng.ui.UI.Conversion1;public class manager_ui extends JFrame {    private JTextField jtfa;
    private JComboBox jComboBox1;
    private JButton jba;
    private JTextField jwordpath;
    private JTextField jwordOpath;
    private JTextField jword;
    private JButton jfilepath;
    private JButton jwordname;
    private JButton jwordOname;
    private JButton jbc;
    private String[] fruit = { "苹果呵呵呵", "香蕉", "桔子", "梨", "芒果" };
    private JButton jtrans;    public manager_ui() {
        super("自动化工具");
    }    public void initUI() {
        // this.getContentPane().setLayout(new GridBagLayout());
        this.setBounds(450, 450, 750, 600);
        this.addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                super.windowClosing(e);
                System.exit(0);
            }
        });
        layoutUI();
        this.setVisible(true);
    }    private void layoutUI() {        // 对象实例化
        JTabbedPane tab = new JTabbedPane(JTabbedPane.TOP);
        // 容器
        Container container = this.getLayeredPane();
        // 对象化面板
        JPanel combop = new JPanel();
        JPanel p1 = new JPanel();
        JPanel p2 = new JPanel();
        // JPanel p3 = new JPanel();
        // JPanel p4 = new JPanel();        tab.add(p1, "第一");
        tab.add(p2, "第二");        // JComboBox<String> jComboBox1=new JComboBox<String>(fruit);
        jComboBox1 = new JComboBox(fruit);
        // jComboBoxTW1.addActionListener(this);
        jComboBox1.setEditable(true);
        // jComboBox1=JComboBox.setLayout();        // 设置jList1对象的带标题边框        // 添加列表框jComboBox1至面板
        p1.add(jComboBox1);        // 下拉框监听
        jComboBox1.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (e.getSource() == jComboBox1.getSelectedItem()) {
                    int index = jComboBox1.getSelectedIndex();
                    switch (index) {
                    case 0:
                        // 这里可以做别的事情，这样写只是为了告诉你有这个方法。
                        // box.getSelectedItem() 的返回值是 object
                        System.out.println(jComboBox1.getSelectedItem()
                                .toString());
                        break;
                    }
                }
            }
        }
        // JComboBox fruit
        // =(comboboxItem)((combobox)e.getSource()).getSelectedItem();
        // JOptionPane.showMessageDialog(null, fruit.getValue());
                );
        // 利用ComboBoxModel建立JComboBox
        // ComboBoxModel myModel=new MyModel();
        // JComboBox jComboBox2=new JComboBox();
        // 设置jList1对象的带标题边框
        // jComboBox2.setBorder(BorderFactory.createTitledBorder("您最喜欢的水果:"));
        // 添加列表框jComboBox2至面板
        // p1.add(jComboBox2);        combop.add(new JLabel("工具"));        getContentPane().setLayout(new BorderLayout());
        getContentPane().add(combop, BorderLayout.NORTH);
        getContentPane().add(tab, BorderLayout.CENTER);
//        container.setLayout(new BorderLayout());
//        container.add(combop, BorderLayout.NORTH);
//        container.add(tab, BorderLayout.CENTER);
        final JFileChooser fc;
        {
            fc = new JFileChooser();
            FileFilter filter = new FileNameExtensionFilter("Excel文件（xlsx）",
                    "xlsx");
            fc.setFileFilter(filter);
        }
        final JFileChooser files;
        {
            files = new JFileChooser();
            FileFilter filter = new FileNameExtensionFilter("Word文件（docx）",
                    "docx");
            files.setFileFilter(filter);
        }
        final JFileChooser files1;
        {
            files1 = new JFileChooser();
            files1.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
        }
        // Container con = frame.getContentPane();
        // con.setLayout(new BorderLayout());        JPanel jpup = new JPanel();
        jpup.setLayout(new GridLayout(5, 2));
        jtfa = new JTextField(30);
        jba = new JButton("选择需要输入的文档");
        jba.addActionListener(        new ActionListener() {            public void actionPerformed(ActionEvent e) {
                int r = fc.showOpenDialog(getContentPane());                if (r == JFileChooser.APPROVE_OPTION) {                    jtfa.setText(fc.getSelectedFile().getPath());                    jbc.setEnabled(true);
                }            }
        }        );
        p1.add(
                new JLabel("<选择需要转化的Excel文档>", SwingConstants.CENTER),
                BorderLayout.CENTER);        jwordpath = new JTextField(30);
        jfilepath = new JButton("选择需要读取的Excel文档");        p1.add(new JLabel("选择输出文档的存放路径", SwingConstants.CENTER),
                BorderLayout.CENTER);        jwordOpath = new JTextField(30);
        jwordOname = new JButton("选择输出文档的存放路径");        jword = new JTextField(30);
        jwordname = new JButton("选择输出文档的存放路径");        jbc = new JButton("开始批处理");
        jbc.addActionListener(new ActionListener() {            public void actionPerformed(ActionEvent e) {                try {
                    // Conversion1.Cnvrt1(jtfa.getText(), jwordpath.getText(),
                    // jword.getText(), jwordOpath.getText());                } catch (Exception ee) {
                    ee.printStackTrace();
                    jbc.setEnabled(true);
                    JOptionPane.showMessageDialog(null, "读取文件失败！");
                    System.out.println(ee.getMessage());
                }
            }
        });
        jtrans = new JButton("             ");
        // jtrans.addActionListener(new ActionListener() {        // @Override
        // public void actionPerformed(ActionEvent e) {
        // System.out.println("hehe \n");
        // }
        // });        p1.add(jtfa);
        p1.add(jba);
        p2.add(jwordpath);
        p2.add(jfilepath);
        p1.add(jwordOpath);
        p1.add(jwordOname);
        p2.add(jword);
        p2.add(jwordname);
        // p1.add(jtrans);
        // p1.add(jbc);    }    public static void main(String[] args) {
        manager_ui ui = new manager_ui();
        ui.initUI();
    }
}