我是黑莓新手。我使用黑莓 9800 模拟器创建 HTTP 连接。我写了以下代码。
public MyScreen()
{
// Set the displayed title of the screen
setTitle("Hello");
ConnectionFactory connFact = new ConnectionFactory();
ConnectionDescriptor connDesc;
connDesc = connFact.getConnection("http://whistlersbest.net/api/categories.php?parent_id=0");
System.out.println("hello " + connFact);
if (connDesc != null)
{
HttpConnection httpConn;
httpConn = (HttpConnection)connDesc.getConnection();
try
{
in = httpConn.openInputStream();
int ii;
while((ii=in.read()) != -1){
strbuffer = strbuffer + (char)ii;
}
}
catch (IOException e)
{
System.err.println("Caught IOException: "
+ e.getMessage());
}
}
setTitle("Whistlers Best");
System.out.println("set Title");
xmlHandler xm = new xmlHandler(strbuffer);
category = xm.getCategory();
System.out.println("category set");
String[] arr = new String[category.getIds().size()];
System.out.println("Array " + arr.length);
list = new ObjectListField(){
protected boolean navigationClick(int status, int time) {
//UiApplication.getUiApplication().pushScreen(new SubCategories(category.getIds().elementAt(list.getSelectedIndex()).toString(),"1",category.getNames().elementAt(list.getSelectedIndex()).toString()));
return false;
}
};
for(int y = 0; y<category.getIds().size() ; y++){
arr[y] = (String)category.getNames().elementAt(y);
System.out.println("string: "+arr[y]);
}
list.set(arr);
VerticalFieldManager hfm = new VerticalFieldManager(Manager.FIELD_HCENTER);
hfm.add(new LabelField("Categories",
Field.FIELD_HCENTER));
hfm.add(list);
list.setChangeListener(this);
add(hfm);
}
它完美地工作。但突然我需要从 Blackberry 9800 切换到 Blackberry 8900 Curve。我使用模拟器并为此编写相同的代码。但我得到了 NullPointerException ：
connDesc = connFact.getConnection("http://whistlersbest.net/api/categories.php?parent_id=0");
我哪里错了？