JAVA 类无法正常工作

【问题标题】：JAVA Class not working properlyJAVA 类无法正常工作
【发布时间】：2015-08-26 06:11:24
【问题描述】：

我有一个加载/重新加载 JComboBox 的方法，我正在使用一个名为 hiddenItem 的类将隐藏值附加到显示值。起初加载 JComboBox 工作良好，但在 Box 重新加载后我收到错误，JComboBox 中的值不是 hiddenItem，那么为什么重新加载后不添加 hiddenItem？也许我需要以某种方式重置或清理 hiddenItem 类？谢谢！

hiddenItem.java:

public class hiddenItem {

    String displayValue;
    Integer hiddenValue;

    //Constructor
    public hiddenItem(String d, Integer h) {
        displayValue = d;
        hiddenValue = h;
    }

    //Accessor
    public Integer get_value() {
        return hiddenValue;
    }

    //Override ToString method
    @Override
    public String toString() {
        return displayValue;
    }
}

加载/重新加载方法：

public static void fill_combos() throws SQLException, ParserConfigurationException, XPathExpressionException, SAXException, IOException, PropertyVetoException {
    Darbai.onload = true;
    ResultSet rs = null;

    darb_combo.removeAllItems();
    ats_combo.removeAllItems();
    darb_combo.addItem(new hiddenItem("ALL", -1));
    ats_combo.addItem(new hiddenItem("ALL", -1));
    rs = select_data(GET_DARBUOTOJAI, null);
    while (rs.next()) {
        darb_combo.addItem(new hiddenItem(rs.getString("name") + " " + rs.getString("surname"), rs.getInt("id")));
        ats_combo.addItem(new hiddenItem(rs.getString("name") + " " + rs.getString("surname"), rs.getInt("id")));
    }
    rs.close();
    darb_combo.setSelectedIndex(0);
    ats_combo.setSelectedIndex(0);

    klientas_combo.removeAllItems();
    klientas_combo.addItem(new hiddenItem("ALL", -1));
    rs = select_data(GET_KLIENTAI, null);
    while (rs.next()) {
        klientas_combo.addItem(new hiddenItem(rs.getString("customer"), rs.getInt("id")));
    }
    rs.close();
    klientas_combo.setSelectedIndex(0);

    busena_combo.removeAllItems();
    busena_combo.addItem(new hiddenItem("ALL", -1));
    busena_combo.addItem(new hiddenItem("Reikia atlikti", 0));
    busena_combo.addItem(new hiddenItem("Skubus", 1));
    busena_combo.addItem(new hiddenItem("Vykdoma", 2));
    busena_combo.addItem(new hiddenItem("Atlikta", 3));
    busena_combo.addItem(new hiddenItem("Užaktuota", 4));
    busena_combo.addItem(new hiddenItem("Garantinis", 5));
    busena_combo.addItem(new hiddenItem("Objektinis", 6));

    AutoCompleteDecorator.decorate(darb_combo);
    AutoCompleteDecorator.decorate(ats_combo);
    AutoCompleteDecorator.decorate(klientas_combo);
    Darbai.onload = false;
}

这是我获得隐藏价值的方法：

if (!Darbai.onload) {
    if (e.getStateChange() == ItemEvent.SELECTED) {
        ResultSet rs = null;
        hiddenItem item = (hiddenItem) e.getItem(); // LINE 805
        Integer id = item.get_value();
        String val = item.displayValue;
     }
}

错误：

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.String cannot be cast to darbai.hiddenItem
at darbai.pagrindinis.itemStateChanged(pagrindinis.java:805)
at javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1223)
at javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1280)
at javax.swing.JComboBox.contentsChanged(JComboBox.java:1329)
at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:118)
at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:93)
at javax.swing.JComboBox.setSelectedItem(JComboBox.java:576)
at org.jdesktop.swingx.autocomplete.ComboBoxAdaptor.setSelectedItem(ComboBoxAdaptor.java:104)
at org.jdesktop.swingx.autocomplete.AutoCompleteDocument.setSelectedItem(AutoCompleteDocument.java:317)
at org.jdesktop.swingx.autocomplete.AutoCompleteDocument.remove(AutoCompleteDocument.java:243)
at javax.swing.text.JTextComponent.setText(JTextComponent.java:1672)
at javax.swing.plaf.metal.MetalComboBoxEditor$1.setText(MetalComboBoxEditor.java:61)
at javax.swing.plaf.basic.BasicComboBoxEditor.setItem(BasicComboBoxEditor.java:87)
at org.jdesktop.swingx.autocomplete.AutoCompleteComboBoxEditor.setItem(AutoCompleteComboBoxEditor.java:78)
at javax.swing.JComboBox.configureEditor(JComboBox.java:1403)
at javax.swing.plaf.basic.BasicComboBoxUI$Handler.contentsChanged(BasicComboBoxUI.java:1864)
at javax.swing.AbstractListModel.fireContentsChanged(AbstractListModel.java:118)
at javax.swing.DefaultComboBoxModel.setSelectedItem(DefaultComboBoxModel.java:93)
at javax.swing.JComboBox.setSelectedItem(JComboBox.java:576)
at javax.swing.JComboBox.setSelectedIndex(JComboBox.java:622)
at javax.swing.plaf.basic.BasicComboPopup$Handler.mouseReleased(BasicComboPopup.java:834)
at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:290)
at java.awt.Component.processMouseEvent(Component.java:6525)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at javax.swing.plaf.basic.BasicComboPopup$1.processMouseEvent(BasicComboPopup.java:498)
at java.awt.Component.processEvent(Component.java:6290)
at java.awt.Container.processEvent(Container.java:2234)
at java.awt.Component.dispatchEventImpl(Component.java:4881)
at java.awt.Container.dispatchEventImpl(Container.java:2292)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4898)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4533)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4462)
at java.awt.Container.dispatchEventImpl(Container.java:2278)
at java.awt.Window.dispatchEventImpl(Window.java:2739)
at java.awt.Component.dispatchEvent(Component.java:4703)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
at java.awt.EventQueue.access$400(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:697)
at java.awt.EventQueue$3.run(EventQueue.java:691)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.awt.EventQueue$4.run(EventQueue.java:719)
at java.awt.EventQueue$4.run(EventQueue.java:717)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

编辑组合定义（由 NetBeans 自动）：

public static javax.swing.JComboBox ats_combo;
public static javax.swing.JComboBox busena_combo;
public static javax.swing.JComboBox darb_combo;
public static javax.swing.JComboBox klientas_combo;

darb_combo = new javax.swing.JComboBox();
ats_combo = new javax.swing.JComboBox();
klientas_combo = new javax.swing.JComboBox();
busena_combo = new javax.swing.JComboBox();

darb_combo.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
ats_combo.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
klientas_combo.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));
busena_combo.setModel(new javax.swing.DefaultComboBoxModel(new String[] { "Item 1", "Item 2", "Item 3", "Item 4" }));

【问题讨论】：

  • 看起来 e.getItem(); 返回一个字符串
  • 但是为什么它应该像第一次加载一样返回 hiddenItem
  • 抱歉没能找到你。你把它放到一个隐藏的物品上：(hiddenItem) e.getItem();
  • 您需要重新检查您的代码。毫无疑问，您希望它返回一个 hiddenItem，但无论是语法还是逻辑，您都犯了一个错误。
  • 考虑提供一个runnable example 来证明您的问题。这不是代码转储，而是您正在做的事情的一个例子，它突出了您遇到的问题。这将减少混乱并获得更好的响应

标签： java class hidden selecteditem


【解决方案1】：

加载您的代码工作正常，但重新加载组合框有默认值，如您列出的那样是字符串值的数组

新字符串[] {“项目 1”、“项目 2”、“项目 3”、“项目 4”}

所以也加载带有 hiddenItem 对象数组作为默认值的组合框。

您已经指出的错误发生在：

hiddenItem item = (hiddenItem) e.getItem(); // LINE 805

由于 getItem 返回您定义的 String 默认对象。 使用以下代码代替组合的默认值

darb_combo.setModel(new javax.swing.DefaultComboBoxModel(new hiddenItem[] { new hiddenItem("Item 1", 1), new hiddenItem("Item 2", 2), new hiddenItem("Item 3",3), new hiddenItem("Item 4",4 }));

附带说明，因为 hiddenItem 是一个类，请遵循约定并将其重命名为 HiddenItem

【讨论】：

  • 我不明白如何默认加载带有隐藏项的组合框，我收到错误字符串不能转换为隐藏项
猜你喜欢
  • 2017-02-17
  • 2017-03-30
  • 2015-02-20
  • 2021-05-11
  • 1970-01-01
  • 1970-01-01
  • 2012-02-20
  • 2011-08-26
相关资源
最近更新 更多
热门标签
Java Python linux javascript Mysql C# Docker 算法 前端 SpringBoot Redis Vue spring 设计模式 .net core .net kubernetes c++ 数据库 数据结构 大数据 js 机器学习 微服务 Android Go 程序员 面试 JVM ASP.net core 云原生 人工智能 后端 PHP git CSS golang k8s Nginx Django mybatis 深度学习 多线程 React 架构 devops 爬虫 云计算 Spring Boot LeetCode