我想将重点放在listfield的第一个元素或项目上。问题是我从其他字段设置焦点（不在列表字段中）。
protected boolean navigationMovement(int dx, int dy, int status, int time) {
while (dy > 0) {
// How to jump into listfield?
Field f = ???
if (f.isFocusable()) {
f.setFocus();
dy--;
}
}
}
这是我的Listfield类。
public class Custom_ListField extends ListField {
private String[] title, category, date, imagepath;
private int[] newsid, catsid;
private List_News newslist;
private Bitmap imagebitmap[], localimage = Config_GlobalFunction
.Bitmap("image_base.png");
private BrowserField webpage;
private boolean islatest;
private Vector content = null, text;
private ListCallback callback = null;
private int currentPosition = 0, j;
private Util_LazyLoader loader;
public Custom_ListField(Vector content, boolean islatest) {
this.content = content;
this.islatest = islatest;
newsid = new int[content.size()];
title = new String[content.size()];
category = new String[content.size()];
date = new String[content.size()];
imagepath = new String[content.size()];
catsid = new int[content.size()];
imagebitmap = new Bitmap[content.size()];
for (int i = 0; i < content.size(); i++) {
newslist = (List_News) content.elementAt(i);
newsid[i] = newslist.getID();
title[i] = newslist.getNtitle();
category[i] = newslist.getNewCatName();
date[i] = newslist.getNArticalD();
imagepath[i] = newslist.getImagePath();
catsid[i] = newslist.getCatID();
if (!imagepath[i].toString().equals("no picture"))
imagebitmap[i] = localimage;
}
initCallbackListening();
Main.getUiApplication().invokeLater(new Runnable() {
public void run() {
for (j = 0; j < imagepath.length; j++) {
if (!imagepath[j].toString().equals("no picture")
&& Config_GlobalFunction.isConnected()) {
loader = new Util_LazyLoader(imagepath[j],
new Util_BitmapDowloadListener() {
public void ImageDownloadCompleted(
Bitmap bmp) {
imagebitmap[j] = bmp;
invalidate();
}
});
loader.run();
}
}
}
}, 500, false);
}
private void initCallbackListening() {
callback = new ListCallback();
this.setCallback(callback);
this.setRowHeight(-2);
}
private class ListCallback implements ListFieldCallback {
public ListCallback() {
}
public void drawListRow(ListField listField, Graphics graphics,
final int index, int y, int width) {
currentPosition = index;
if (!imagepath[index].toString().equals("no picture")) {
float ratio = (float) ((float) localimage.getHeight() / (float) imagebitmap[index]
.getHeight());
Bitmap temp = new Bitmap(
(int) (imagebitmap[index].getWidth() * ratio),
(int) (imagebitmap[index].getHeight() * ratio));
imagebitmap[index].scaleInto(temp, Bitmap.FILTER_BILINEAR,
Bitmap.SCALE_TO_FIT);
imagebitmap[index] = temp;
graphics.drawBitmap(
Display.getWidth()
- localimage.getWidth()
- 5
+ ((localimage.getWidth() - imagebitmap[index]
.getWidth()) / 2),
y
+ (listField.getRowHeight(index) - imagebitmap[index]
.getHeight()) / 2,
imagebitmap[index].getWidth(),
imagebitmap[index].getHeight(), imagebitmap[index], 0,
0);
graphics.setColor(Color.BLACK);
text = Config_GlobalFunction
.wrap(title[index], Display.getWidth()
- imagebitmap[index].getWidth() - 15);
for (int i = 0; i < text.size(); i++) {
int liney = y + (i * Font.getDefault().getHeight());
graphics.drawText(
(String) text.elementAt(i),
5,
liney + 3,
DrawStyle.TOP | DrawStyle.LEFT | DrawStyle.ELLIPSIS,
Display.getWidth() - imagebitmap[index].getWidth()
- 10);
}
} else {
graphics.setColor(Color.BLACK);
text = Config_GlobalFunction.wrap(title[index],
Display.getWidth() - 10);
for (int i = 0; i < text.size(); i++) {
int liney = y + (i * Font.getDefault().getHeight());
graphics.drawText(
(String) text.elementAt(i),
5,
liney + 3,
DrawStyle.TOP | DrawStyle.LEFT | DrawStyle.ELLIPSIS,
Display.getWidth() - 10);
}
}
if (text.size() == 2) {
graphics.setColor(Color.GRAY);
graphics.drawText(date[index], 5, y
+ Font.getDefault().getHeight() + 3);
if (islatest) {
graphics.setColor(Color.RED);
graphics.drawText(category[index], Font.getDefault()
.getAdvance(date[index]) + 15, y
+ Font.getDefault().getHeight() + 3);
}
} else if (text.size() == 3) {
graphics.setColor(Color.GRAY);
graphics.drawText(date[index], 5, y
+ Font.getDefault().getHeight() * 2 + 3);
if (islatest) {
graphics.setColor(Color.RED);
graphics.drawText(category[index], Font.getDefault()
.getAdvance(date[index]) + 15, y
+ Font.getDefault().getHeight() * 2 + 3);
}
}
if (!imagepath[index].toString().equals("no picture"))
setRowHeight(index, imagebitmap[index].getHeight() + 10);
else {
if (text.size() == 2)
setRowHeight(index, getRowHeight() + 9);
else if (text.size() == 3) {
setRowHeight(index, getRowHeight() * 15 / 10 + 9);
}
}
graphics.setColor(Color.WHITE);
graphics.drawRect(0, y, width, listField.getRowHeight(index));
}
public Object get(ListField listField, int index) {
return content.elementAt(index);
}
public int getPreferredWidth(ListField listField) {
return Display.getWidth();
}
public int indexOfList(ListField listField, String prefix, int start) {
return content.indexOf(prefix, start);
}
}
public int getCurrentPosition() {
return currentPosition;
}
protected boolean navigationClick(int status, int time) {
final int index = getCurrentPosition();
Main.getUiApplication().pushScreen(new Custom_LoadingScreen(1));
Main.getUiApplication().invokeLater(new Runnable() {
public void run() {
if (catsid[index] == 9) {
if (Config_GlobalFunction.isConnected()) {
webpage = new BrowserField();
MainScreen aboutus = new Menu_Aboutus();
aboutus.add(webpage);
Main.getUiApplication().pushScreen(aboutus);
webpage.requestContent("http://www.orientaldaily.com.my/index.php?option=com_k2&view=item&id="
+ newsid[index]
+ ":&Itemid=223"
+ Database_Webservice.ht_params);
} else
Config_GlobalFunction.Message(
Config_GlobalFunction.nowifi, 1);
} else {
Main.getUiApplication().pushScreen(
new Main_NewsDetail(newsid[index]));
}
}
}, 1 * 1000, false);
return true;
}
}
我尝试使用.get，但当我检查isFocusable()时，它会返回NullPointerException。
我不确定如何获得正确的字段。
答案 0 :(得分：1)
最后我找到了解决方案。
它由两层字段组成。在将内部设置为第一个元素之后，外部必须设置为listfield。
while (dy > 0) {
Field f = listfield;
if (f.isFocusable()) {
f.setFocus(); //outer field
listfield.setSelectedIndex(0); //inner field
dy--;
}
}