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我是primefaces的新手。当我生成 PieChart 即使用静态或示例信息设置 PieChartModel 时，它工作正常，但是当我使用数据库中的数据时，它给了我 java.lang.NullPointerException

我的豆子

public class ChartControllerPie {
    @EJB
    private session.SubscribeFacade ejbsubscribe;

    public List<String> v() {
        return ejbsubscribe.allVille();
    }
    private PieChartModel pieModel;

    public ChartControllerPie() {
        createPieModel();
    }

    public PieChartModel getPieModel() {
        return pieModel;
    }

    private void createPieModel() {
        pieModel = new PieChartModel();

        pieModel.set("bouhajla", 1540);
        pieModel.set("meknasi", 325);
        pieModel.set("mater", 702);
        pieModel.set("najta", 421);
    }
}

此方法返回结果

   @EJB
    private session.SubscribeFacade ejbsubscribe;

    public List<String> v() {
        return ejbsubscribe.allVille();
    }

但是当我添加这个 v(); ？？？不工作我的豆

    public class ChartControllerPie {
    @EJB
    private session.SubscribeFacade ejbsubscribe;

    public List<String> v() {
        return ejbsubscribe.allVille();
    }
    private PieChartModel pieModel;

    public ChartControllerPie() {
        createPieModel();
    }

    public PieChartModel getPieModel() {
        return pieModel;
    }

    private void createPieModel() {
        pieModel = new PieChartModel();
        v();// for use data
        pieModel.set("bouhajla", 1540);
        pieModel.set("meknasi", 325);
        pieModel.set("mater", 702);
        pieModel.set("najta", 421);
    }
}

只是问题是从数据库创建 PieChartModel

    <?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:p="http://primefaces.org/ui"
      xmlns:ui="http://java.sun.com/jsf/facelets">

    <ui:composition template="statistiquefaces.xhtml">

        <ui:define name="title">
        </ui:define>


        <ui:define name="centre">
    <p:pieChart id="custom" value="#{chartControllerPie.pieModel}" legendPosition="e" fill="false" showDataLabels="true"
                            title="Custom Options" style="width:400px;height:300px" sliceMargin="5" diameter="150" /> 

     </ui:define>
        </ui:composition>
    </html>
4

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