Bean属性“ listpoints”不可写或具有无效的setter方法

Question

    My Bean.xml has
    <bean id = "triangle" class="com.cg.collectionss.Triangle">
       <property name="listpoints">
       <list>
       <ref bean ="point"/>
       <ref bean ="point1"/></list>
        </property>

       </bean>

       <bean id="point" class="com.cg.collectionss.Point">
       <property name="x" value="hello"></property>
       <property name="y" value="world"></property>



    package com.cg.collectionss;

    import java.util.List;

    public class Triangle
    {
        private List<Point> listpoints;
         public void setListPoints(List<Point> points)
    {
        listpoints= points;
    }

         public List<Point> getListPoints()
         {
             return listpoints;
         }
    }

  

错误：由以下原因引起：org.springframework.beans.NotWritablePropertyException：Bean类[com.cg.collectionss.Triangle]的无效属性“ listpoints”：Bean属性“ listpoints”不可写，或者具有无效的setter方法。您是说“ listPoints”吗？       在org.springframework.beans.BeanWrapperImpl.createNotWritablePropertyException（BeanWrapperImpl.java:243）       在org.springframework.beans.AbstractNestablePropertyAccessor.processLocalProperty（AbstractNestablePropertyAccessor.java:426）       在org.springframework.beans.AbstractNestablePropertyAccessor.setPropertyValue（AbstractNestablePropertyAccessor.java:278）       在org.springframework.beans.AbstractNestablePropertyAccessor.setPropertyValue（AbstractNestablePropertyAccessor.java:266）       在org.springframework.beans.AbstractPropertyAccessor.setPropertyValues（AbstractPropertyAccessor.java:97）       在org.springframework.beans.AbstractPropertyAccessor.setPrope ................

当我将Bean.xml中的属性名称更改为ListPoints时，得到了预期的输出。为什么不能将属性名称listpoints作为属性名称？。