尝试在eclipse中运行餐厅应用程序时出现以下错误:
java.lang.NullPointerException,com.myrestaurant.app.ui.MainMenuForm.lambda $ 0(MainMenuForm.java:73)at com.codename1.ui.util.EventDispatcher.fireSelectionSync(EventDispatcher.java:321)at com.codename1.ui .util.EventDispatcher.fireSelectionEvent(EventDispatcher.java:402)at com.codename1.ui.list.DefaultListModel.setSelectedIndex(DefaultListModel.java:181)at com.codename1.ui.List.initComponentImpl(List.java:329)at com.codename1.ui.ui.Container.initComponentImpl(Container.java:979)com.codename1.ui.Container.insertComponentAtImpl(Container.java:715)at com.codename1.ui.Container.insertComponentAt(Container.java:687) at com.codename1.ui.Container.addComponent(Container.java:641)at com.codename1.ui.Form.addComponent(Form.java:1207)at com.codename1.ui.Container.add(Container.java:281) )com.myrestaurant.app.ui.BaseForm.init(BaseForm.java:102)at com.myrestaurant.app.ui.BaseForm . (BaseForm.java:34)at com.myrestaurant.app.ui.MainMenuForm . ( MainMenuForm.java:43)在com.myrestaurant.app.ui .BaseForm.showMainMenuForm(BaseForm.java:156)位于sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl)的sun.reflect.NativeMethodAccessorImpl.invoke0(本地方法)中的com.myrestaurant.app.MyRestaurant.start(MyRestaurant.java:48) .java:62)at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)at java.lang.reflect.Method.invoke(Method.java:498)at com.codename1.impl.javase.Executor $ 1 $ 1 . 运行(Executor.java:123)com.codename1.ui.Display.processSerialCalls(Display.java:1154)at com.codename1.ui.Display.mainEDTLoop(Display.java:971)at com.codename1.ui.RunnableWrapper .run(RunnableWrapper.java:120)at com.codename1.impl.CodenameOneThread.run(CodenameOneThread.java:176)
有什么帮助吗?
方法如下:
@Override
protected List<String> createCategoryList() {
if(Restaurant.getInstance().
menu.get().
categories.size() == 0) {
categoryModel = new DefaultListModel<>("Loading...");
} else {
categoryModel = new DefaultListModel<>(
Restaurant.getInstance().
menu.get().
categories.asList());
}
List<String> l = new List<String>(categoryModel) {
@Override
protected boolean shouldRenderSelection() {
return true;
}
};
((DefaultListCellRenderer<String>)l.getRenderer()).setAlwaysRenderSelection(true);
l.setIgnoreFocusComponentWhenUnfocused(false);
l.setOrientation(List.HORIZONTAL);
l.setFixedSelection(List.FIXED_CENTER);
l.addSelectionListener((i, ii) -> {
if(currentCategory != l.getSelectedItem()) {
currentCategory = l.getSelectedItem();
for(Component c : dishesContainer) {
Dish d = (Dish)c.getClientProperty("dish");
***boolean hidden = d.category.get().equals(currentCategory);***
c.setHidden(hidden);
c.setVisible(!hidden);
}
dishesContainer.animateLayout(150);
}
});
return l;
}
2 回答
随着课程的进展,这在应用程序的后续迭代中得到修复 . 这是此块的当前代码:
这时我还没有完成上传所有内容,但我正在努力 .
删除列表侦听器中的“***”字符...似乎其中一个变量为null:
currentCategory
dishesContainer
d
d.category