Question

我对编程有点新意，很抱歉，如果有一些事情可以做得更好我的组合框成功填充了我的字符串数组，自动完成工作正常。我只是无法在组合框中获取文本。

返回java.lang.NullPointerException

private ArrayList<String> arrRekening;
private ArrayList<String> arrEienaar;
private String[] sarrRekening;
private String[] sarrEienaar;

    public NewConnectionPoint() {

    arrAccount = new ArrayList<String>();
    arrOwner = new ArrayList<String>();

    FillCombo(arrAccount , "Owners", "OwnerName");
    FillCombo(arrOwner , "Accounts", "AccountName");
    sarrOwner= arrOwner.toArray(new String[arrOwner .size()]);
    sarrAccount= arrAccount.toArray(new String[arrAccount.size()]);

    JComboBox<String> comboAccount = new JComboBox<String>();
    AutoCompleteSupport<String> supAccount = AutoCompleteSupport.install(comboRekening, GlazedLists.eventList(Arrays.asList(sarrAccount)));
    supAccount.setStrict(true);

    JComboBox<String> comboOwner = new JComboBox<String>();
    AutoCompleteSupport<String> supOwner = AutoCompleteSupport.install(comboOwner,GlazedLists.eventList(Arrays.asList(sarrOwner)));
    supOwner.setStrict(true);

    JButton btnShow = new JButton("ShowSelectedr");
    btnShow.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) { 
        //Error occurs at this line 
            JOptionPane.showMessageDialog(null, comboOwner.getSelectedItem().toString());

    });}

}

//使用sql

从数据库加载到arraylists中的数据

private void FillCombo(ArrayList<String> ComboElements, String sTable, String sColumn){
try{
    Data.changeQuery(sTable);// database connection fine returns and fills combobox 

    while(MyData.rs.next()){
        String sReturn= MyData.rs.getString(sColumn);
        ComboElements.add(sReturn);
    }

}catch(Exception e){
    JOptionPane.showMessageDialog(null, e);
}

}

Answer 1

您在这里遇到的根本困难是，您在尝试利用GlazedLists软件包时没有正确使用它的核心实用程序：EventLists。

如果使用EventLists而不是ArrayLists，则可以轻松地解决困难。

如果你真的想要，你可以保持你的FillCombo方法返回一个ArrayList（也许更好的名称为getElements()）但是直接启动一个EventList，使用GlazedLists EventComboBoxModel将EventList链接到JComboBox然后你会发现你的组合框getSelectedItem（）应该可以正常工作。

将列表链接到具有自动完成支持的组合框的修改代码将如下所示：

...
FillCombo(arrOwner , "Owners", "OwnerName");
EventList<String> ownerEventList = GlazedLists.eventList(arrOwner);
EventComboBoxModel<String> ownerModel = new EventComboBoxModel<String>(ownerEventList);
JComboBox comboOwner = new JComboBox(ownerModel);
AutoCompleteSupport<String> supOwner = AutoCompleteSupport.install(comboOwner,ownerEventList);
supOwner.setStrict(true);
...

带有GlazedLists的getSelectedItem JComboBox AutocompleteSupport返回Null

1 个答案: