我正在开发一个应用程序，在该应用程序中，我可以根据将flag设置为true或false来添加和删除字段。但我要做的是，如果我单击某个字段，则该字段应该展开，而其他字段则被折叠（即使它已展开）我在谷歌上搜索了一下，但没有找到解决方案。请帮帮我，我是黑莓java 的新手
我使用了以下代码的
public final class MyScreen extends MainScreen implements
FieldChangeListener
{
/**
* Creates a new MyScreen object
*/
private VerticalFieldManager main_manager;
private HorizontalFieldManager parentNodes;
private LabelField parent_lables[];
private Bitmap bitmap,upbitmap;
private BitmapField bitmap_field[];
private VerticalFieldManager submanager[];
private int sizeOfParentNodes=3;
private int sizeOfChildNodes=5;
private static boolean flag[];
public MyScreen()
{
// Set the displayed title of the screen
bitmap=Bitmap.getBitmapResource("arrow.png");
upbitmap=Bitmap.getBitmapResource("uparrow.png");
main_manager=new
VerticalFieldManager(Manager.VERTICAL_SCROLL|VERTICAL_SCROLLBAR){
protected void sublayout(int maxWidth, int maxHeight) {
super.sublayout(Display.getWidth(), Display.getHeight());
setExtent(Display.getWidth(), Display.getHeight());
};
};
parent_lables=new LabelField[sizeOfParentNodes];
flag=new boolean[sizeOfParentNodes];
submanager=new VerticalFieldManager[sizeOfParentNodes];
bitmap_field=new BitmapField[sizeOfParentNodes];
for(int i=0;i<sizeOfParentNodes;i++)
{
submanager[i]=new VerticalFieldManager();
updateGUI(i);
main_manager.add(submanager[i]);
}
add(main_manager);
}
public void fieldChanged(Field field, int context) {
// TODO Auto-generated method stub
synchronized (UiApplication.getEventLock()) {
for(int i=0;i<sizeOfParentNodes;i++)
{ if(field==parent_lables[i])
{
if(flag[i]==true){
flag[i]=false;
submanager[i].deleteAll();
updateGUI(i);
parent_lables[i].setFocus();
}else{
flag[i]=true;
bitmap_field[i].setBitmap(upbitmap);
submanager[i].invalidate();
}
}
}
}
}
public void updateGUI(int index)
{
parentNodes=new HorizontalFieldManager(USE_ALL_WIDTH);
bitmap_field[index]=new BitmapField(bitmap);
parentNodes.add(bitmap_field[index]);
parent_lables[index]=new LabelField("Day"+index,Field.FOCUSABLE){
protected boolean navigationClick(int status, int time) {
fieldChangeNotify(1);
return true;
};
};
parentNodes.add(parent_lables[index]);
parent_lables[index].setChangeListener(this);
submanager[index].add(parentNodes);
}
}
我把它拼凑在一起，可能需要你进行一些调整才能得到你想要的东西，但它应该是你可以使用的东西。假设我正确理解了你的问题。
您需要创建一个基字段、一个能够管理它们列表的助手和一个回调。您需要一个基本字段这一事实是最大的缺点，因为它会立即排除您拥有的所有其他小部件，因为它们需要使用paint方法从头开始制作。通过扩展VerticalFieldManager而不是Field，可以使用VerticalFieldManager而不是字段。
转到java类。我的CollapsableField.java如下所示：
public abstract class CollapsableField extends Field
{
// We make use of a different listener than the FieldChangeListener, since you can only attach one and we will most likely want to do so, we can't "occupy" the listener.
private CollapseListener listener;
private boolean collapsed;
protected int collapsedWidth;
protected int collapsedHeight;
public CollapsableField()
{
collapsed = true;
// Field is completely collapsed by default
collapsedWidth = 0;
collapsedHeight = 0;
}
public void setCollapseListener(CollapseListener listener)
{
this.listener = listener;
}
public final boolean isCollapsed()
{
return collapsed;
}
public final void collapse()
{
this.collapsed = true;
if (listener != null)
{
listener.onCollapse(this);
}
fieldChangeNotify(0); // Notify that the field has changed, so that attached field change listeners will fire
updateLayout(); // re-call layout
}
public final void expand()
{
this.collapsed = false;
if (listener != null)
{
listener.onExpand(this);
}
fieldChangeNotify(0); // Notify that the field has changed, so that attached field change listeners will fire
updateLayout(); // re-call layout
}
protected void layout(int width, int height)
{
if (collapsed)
{
// Set dimensions to collapsed
setExtent(collapsedWidth, collapsedHeight);
}
else
{
// Set dimensions to what the extending class specified
setExtent(width, height);
}
}
protected final void paint(Graphics graphics)
{
if (collapsed)
{
paintCollapsed(graphics);
}
else
{
paintExpanded(graphics);
}
}
protected abstract void paintCollapsed(Graphics graphics);
protected abstract void paintExpanded(Graphics graphics);
}
然后，Group获取这些字段的列表，并在添加字段时将侦听器应用于每个字段。当一个场发出它已经扩展的信号时，该组会告诉所有其他场自行塌陷。CollapsableGroup.java：
public class CollapsableGroup
{
private Vector fields;
private CollapseListener listener;
public CollapsableGroup()
{
fields = new Vector();
listener = new CollapseListener()
{
public void onExpand(CollapsableField source)
{
for (int i = 0; i < fields.size(); i++)
{
CollapsableField field = (CollapsableField) fields.elementAt(i);
if ((!field.isCollapsed()) && (field != source))
{
field.collapse();
}
}
}
public void onCollapse(CollapsableField source)
{
// Don't need to handle this. Method is here just for completeness
}
};
}
public void add(CollapsableField field)
{
field.setCollapseListener(listener);
fields.addElement(field);
}
public void remove(CollapsableField field)
{
field.setCollapseListener(null);
fields.removeElement(field);
}
/**
* Returns the currently expanded field. Returns <b>null</b> if all fields are collapsed.
*
* @return
*/
public CollapsableField getExpandedField()
{
for (int i = 0; i < fields.size(); i++)
{
CollapsableField field = (CollapsableField) fields.elementAt(i);
if (!field.isCollapsed())
{
return field;
}
}
return null;
}
public void expand(CollapsableField field)
{
field.expand(); // Listeners should take care of the rest
}
public void collapseAll()
{
for (int i = 0; i < fields.size(); i++)
{
CollapsableField field = (CollapsableField) fields.elementAt(i);
if (!field.isCollapsed())
{
field.collapse();
}
}
}
}
最后是监听器接口。CollapseListener.java:
interface CollapseListener
{
public void onExpand(CollapsableField source);
public void onCollapse(CollapsableField source);
}
这三门课应该是你所需要的全部。下面的类是我的示例/测试类。TestLabel.java是一个扩展类的例子：
public class TestLabel extends CollapsableField
{
private String text;
private String collapsedText;
public TestLabel(String text, String collapsedText)
{
this.text = text;
this.collapsedText = collapsedText;
// Tells the layout method to collapse to the size of this text
collapsedWidth = getFont().getAdvance(collapsedText);
collapsedHeight = getFont().getHeight();
}
public int getPreferredWidth()
{
return getFont().getAdvance(text);
}
public int getPreferredHeight()
{
return getFont().getHeight();
}
protected void layout(int width, int height)
{
super.layout(getPreferredWidth(), getPreferredHeight());
}
protected void paintCollapsed(Graphics graphics)
{
// Paints only the collapsedText
graphics.drawText(collapsedText, 0, 0);
}
protected void paintExpanded(Graphics graphics)
{
// Paints the full Text
graphics.drawText(text, 0, 0);
}
protected boolean touchEvent(TouchEvent message)
{
// Toggle on mouse press
if (message.getEvent() == TouchEvent.CLICK)
{
if (isCollapsed())
{
expand();
}
else
{
collapse();
}
return true;
}
return super.touchEvent(message);
}
}
下面的屏幕包含一些字段，显示小部件本身和组都可以操作这些字段。MyScreen.java：
public final class MyScreen extends MainScreen
{
public MyScreen()
{
// Set the displayed title of the screen
setTitle("MyTitle");
final CollapsableGroup group = new CollapsableGroup();
final TestLabel label1 = new TestLabel("Label1", "L1");
label1.setBackground(BackgroundFactory.createSolidBackground(0x999999));
group.add(label1);
final TestLabel label2 = new TestLabel("Label2", "L2");
label2.setBackground(BackgroundFactory.createSolidBackground(0xBBBBBB));
group.add(label2);
final TestLabel label3 = new TestLabel("Label3", "L3");
label3.setBackground(BackgroundFactory.createSolidBackground(0xDDDDDD));
group.add(label3);
ButtonField collapseAll = new ButtonField("Collapse All")
{
protected boolean navigationClick(int status, int time)
{
group.collapseAll();
return true;
}
};
add(collapseAll);
ButtonField expand1 = new ButtonField("Expand1")
{
protected boolean navigationClick(int status, int time)
{
group.expand(label1);
return true;
}
};
add(expand1);
ButtonField expand2 = new ButtonField("Expand2")
{
protected boolean navigationClick(int status, int time)
{
group.expand(label2);
return true;
}
};
add(expand2);
ButtonField expand3 = new ButtonField("Expand3")
{
protected boolean navigationClick(int status, int time)
{
group.expand(label3);
return true;
}
};
add(expand3);
add(label1);
add(label2);
add(label3);
}
}