Java ClassCastException错误(对象和向量)
我正在与LWUIT List合作。以下是创建列表的方式:Java ClassCastException错误(对象和向量),java,java-me,lwuit,Java,Java Me,Lwuit,我正在与LWUIT List合作。以下是创建列表的方式: db = new ClientDB(); listclient = db.listClient(); tModel = new ListSource(listclient); renderer = new CListCell(true, new String[]{"", "", "Encours : ", "Impayés : "}); tList = new CList(tModel, renderer); public Vector
db = new ClientDB();
listclient = db.listClient();
tModel = new ListSource(listclient);
renderer = new CListCell(true, new String[]{"", "", "Encours : ", "Impayés : "});
tList = new CList(tModel, renderer);
public Vector listClient()
{
try
{
filter = new Filter("");
comparator = new Comparator();
enumRec = this.enumerateRecords(filter, comparator);
while(enumRec.hasNextElement())
{
id = enumRec.nextRecordId();
recIDs.addElement(new Integer(id));
bData = this.getRecord(id);
client = new Client(bData);
if (!innerResultat.isEmpty())
{
innerResultat.removeAllElements();
}
innerResultat.addElement(new String(client.getIdclient()));
innerResultat.addElement(new String(client.getCin()));
innerResultat.addElement(new String(client.getNoms()));
innerResultat.addElement(new String(client.getEncours()));
innerResultat.addElement(new String(client.getImpayes()));
resultat.addElement(innerResultat);
}
}
catch (Exception ex) {
ex.printStackTrace();
}
return resultat;
}
public class ListSource extends DefaultListModel {
public ListSource(Vector valeur)
{
super(valeur);
}
public int getListIDs(int ligneSelected)
{
return ligneSelected;
}
}
public class CListCell extends Container implements ListCellRenderer {
private boolean isPhotoDisplayed;
private BorderLayout photoLayout = new BorderLayout();
private BoxLayout yLayout = new BoxLayout(BoxLayout.Y_AXIS);
private Vector vLabels = new Vector();
private Label pic = new Label("");
private Container cnt;
private Font fontLibelle = (MenuPrincipalForm.r).getFont("FontTextFieldBold");
private Label focus = new Label("");
public CListCell(boolean displayPhoto, String[] libelles)
{
isPhotoDisplayed = displayPhoto;
this.getSelectedStyle().setPadding(0, 0, 0, 0);
this.getUnselectedStyle().setPadding(0, 0, 0, 0);
if (displayPhoto)
{
setLayout(photoLayout);
addComponent(BorderLayout.WEST, pic);
}
else
{
setLayout(yLayout);
}
cnt = new Container(yLayout);
for (int i=0;i<libelles.length;i++)
{
vLabels.addElement(new Label(libelles[i]));
((Label)vLabels.elementAt(i)).getStyle().setBgTransparency(0);
((Label)vLabels.elementAt(i)).getStyle().setFont(fontLibelle);
cnt.addComponent(((Label)vLabels.elementAt(i)));
}
addComponent(BorderLayout.CENTER, cnt);
focus.getStyle().setBgTransparency(100);
}
public Component getListCellRendererComponent(List list, Object value, int index, boolean isSelected)
{
Vector reelData = new Vector();
if (value != null && (value instanceof Vector))
{
if (((Vector)value).isEmpty())
{
if (isPhotoDisplayed)
pic.setIcon(null);
for (int i=0; i<vLabels.size(); i++)
((Label)vLabels.elementAt(i)).setText(((Label)vLabels.elementAt(i)).getText().concat("-"));
}
else
{
reelData = (Vector)((Vector)value).elementAt(index);
for (int i=0; i<vLabels.size(); i++)
((Label)vLabels.elementAt(i)).setText(((Label)vLabels.elementAt(i)).getText().concat(String.valueOf(reelData.elementAt(i+1))));
pic.setIcon(null);
}
}
return this;
}
public Component getListFocusComponent(List list)
{
return focus;
}
}
public class CList extends List {
public CList(ListSource model, CListCell renderer)
{
setModel(model);
setListCellRenderer(renderer);
setItemGap(0);
setFixedSelection(List.FIXED_NONE_CYCLIC);
}
}
一般来说,检查是否可以进行强制转换是一个好主意。在你的例子中,你似乎得到了一些不是向量的物体
if (value != null && value instanceof Vector) {
Vector vector = (Vector) value;
... your body with vector instead of value
} else {
throw new IllegalArgumentException("Man I didn't get a Vector!");
}
你是否考虑过使用泛型类型?
你仍然在压制异常的重要部分,告诉你它应该是哪个对象。发布实际堆栈跟踪。您在列表上传递的对象是什么?@bharath:这是向量的向量,我将其作为其数据源模型传递给列表。您能告诉您的代码如何传递列表中的值吗?为什么在这个问题上有java me标记?您是否在JavaME中执行此代码?有一点非常奇怪:我编写了此代码:if(value!=null&(value instanceof Vector))
在强制转换之前,应用程序进入if
块(我编写了一个System.out.println)。但是当输入if
块时,就会引发ClassCastException!我打印了向量的元素数,它显示了3。那么该怎么办呢?那么您对异常源的诊断是错误的。你能发布你修改过的代码和完整的堆栈跟踪吗?你使用过任何框架来修改类的字节码吗?我不知道。据我所知,我已经下载了Sun Java ME平台SDK 3.0,而Oracle JDK for Windows Java ME没有泛型,它基于JDK 1.3(参见维基百科中的egg)
if (value != null && value instanceof Vector) {
Vector vector = (Vector) value;
... your body with vector instead of value
} else {
throw new IllegalArgumentException("Man I didn't get a Vector!");
}