Question

我遇到了SelectableDataModel和ViewScope的问题。以下是我实施的内容：的facelet：

<p:dataTable id="countries"
        value="#{userPreferencesBean.countryDataModel}"
        var="country" emptyMessage="No Country found."
        selection="#{userPreferencesBean.selectedCountries}"
        styleClass="table-no-select-all" dynamic="true" rowKey="#{country.id}">
        ......
</p:dataTable>

支持Bean：

@ManagedBean(name = UserPreferencesBean.MANAGEDBEAN_NAME)
@ViewScoped
public class UserPreferencesBean implements Serializable {

  //All Variable Declarations goes here
  @PostConstruct
  public void initialize() {
      List<Country> coountries = Getting countries from DB
      setCountryDataModel(new CountryDataModel(coountries));
  }
  public void preRender(ComponentSystemEvent event) {
      //Nothing here
  }
  ...
}

CountryDataModel：

@ManagedBean(name = CountryDataModel.MANAGEDBEAN_NAME)
@ViewScoped
public class CountryDataModel extends ListDataModel<Country> implements SelectableDataModel<Country>,
    Serializable {
    public CountryDataModel() {
    }

    public CountryDataModel(List<Country> countries) {
        super(countries);
    }

    @Override
    public Interface getRowData(String rowKey) {
        @SuppressWarnings("unchecked")
        List<Country> countries = (List<Country>)getWrappedData();
        for (Country singleCountry : countries) {
            if (isEqualWithRowKey(singleCountry.getId(), rowKey))
                return singleCountry;
        }
        return null;
    }

    private boolean isEqualWithRowKey(Short countryId, String rowKey) {
        Short rowKeyId = Short.parseShort(rowKey);
        if (countryId.equals(rowKeyId))
            return true;
        return false;
    }

    @Override
    public Object getRowKey(Country singleCountry) {
        return singleCountry.getId();
    }
}

现在发生的事情是第一次正确加载数据表。但是当我点击某一行时，我正在接受NPE。记录如下：

Caused by: java.lang.NullPointerException
    at org.primefaces.component.datatable.DataTable.getRowData(DataTable.java:936)
    at org.primefaces.component.datatable.feature.SelectionFeature.decodeMultipleSelection(SelectionFeature.java:71)
    at org.primefaces.component.datatable.feature.SelectionFeature.decode(SelectionFeature.java:40)
    at org.primefaces.component.datatable.DataTableRenderer.decode(DataTableRenderer.java:57)
    at javax.faces.component.UIComponentBase.decode(UIComponentBase.java:415)

使用SelectableDataModel的NullPointerException和使用PrimeFaces的ViewScope

0 个答案: