我对为什么这不起作用感到困惑。我在Firestore中的文档中有一个数组（daysOfWeek），我需要在recyclerview的视图持有器中显示该数组。我从文档中提取的字符串，整数，长整型等都很好，但是我无法弄清楚如何将arraylist转换为字符串。仅在某些情况下，该数组包含用户在一周中选择的日期，我需要相应的textview来显示一周中所有选择的日期。
这是我的适配器代码的一部分：
public class MealPlanDetailsAdapter extends RecyclerView.Adapter<MealPlanDetailsAdapter.MealPlanDetailsViewHolder> {
private Context adapterContext;
private ArrayList<MealplanDetails> mealplanDetailsArrayList;
private final static String TAG = MealPlanDetailsAdapter.class.getSimpleName();
public MealPlanDetailsAdapter(Context adapterContext, ArrayList<MealplanDetails> mealplanDetailsArrayList) {
this.mealplanDetailsArrayList = mealplanDetailsArrayList;
this.adapterContext = adapterContext;
}
@NonNull
@Override
public MealPlanDetailsAdapter.MealPlanDetailsViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
LayoutInflater layoutInflater = LayoutInflater.from(adapterContext);
View view = layoutInflater.inflate(R.layout.mealplan_card, viewGroup, false);
return new MealPlanDetailsViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull MealPlanDetailsAdapter.MealPlanDetailsViewHolder mpDetailsViewHolder, int position) {
// Set days of week
StringBuilder stringBuilder = new StringBuilder();
for (Object day : mealplanDetailsArrayList.get(position).getDaysOfWeek())
{
stringBuilder.append(day.toString());
stringBuilder.append(" ");
}
String finalDays = stringBuilder.toString();
Log.d(TAG, "days of the week:" + finalDays);
mpDetailsViewHolder.tvDaysOfWeek.setText(finalDays);
// Set restaurant
// Set menu items
}
class MealPlanDetailsViewHolder extends RecyclerView.ViewHolder {
public tvDaysOfWeek
public MealPlanDetailsViewHolder(@NonNull View itemView) {
super(itemView);
tvDaysOfWeek = itemView.findViewById(R.id.days_week);
}
}
我的回收站工作正常。适配器没有问题。但是它导致问题的这个数组。堆栈跟踪如下：
Process: com.healthplan, PID: 20051
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
at com.healthplan.MealPlanDetailsAdapter.onBindViewHolder(MealPlanDetailsAdapter.java:65)
答案 0 :(得分：0)
此问题与Firestore无关。 2019-06-06 16:02:22 ERROR o.s.boot.SpringApplication - Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: Unknown mappedBy in: hello.model.League.teams, referenced property unknown: java.util.Set.league
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:856)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737)
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:314)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151)
at hello.Application.main(Application.java:47)
Caused by: org.hibernate.AnnotationException: Unknown mappedBy in: hello.model.League.teams, referenced property unknown: java.util.Set.league
at org.hibernate.cfg.OneToOneSecondPass.doSecondPass(OneToOneSecondPass.java:147)
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1655)
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1623)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:278)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:847)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:874)
at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60)
at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:353)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:373)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:362)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624)
... 15 common frames omitted
Process finished with exit code 1
为空。这意味着您试图找到TextView的代码行是错误的：
mpDetailsViewHolder.tvDaysOfWeek您必须弄清楚TextView的位置并正确识别它。