類在jar包里,不方便直接修改類..想自定義一個類繼承那個類增加屬性:publicclassPageextendsArrayList{/***不進(jìn)行count查詢*/privatestaticfinalintNO_SQL_COUNT=-1;/***進(jìn)行count查詢*/privatestaticfinalintSQL_COUNT=0;privateintpageNum;privateintpageSize;privateintstartRow;privateintendRow;privatelongtotal;privateintpages;publicPage(intpageNum,intpageSize){this(pageNum,pageSize,SQL_COUNT);}publicPage(intpageNum,intpageSize,booleancount){this(pageNum,pageSize,count?Page.SQL_COUNT:Page.NO_SQL_COUNT);}publicPage(intpageNum,intpageSize,inttotal){super(pageSize>-1?pageSize:0);this.pageNum=pageNum;this.pageSize=pageSize;this.total=total;this.startRow=pageNum>0?(pageNum-1)*pageSize:0;this.endRow=pageNum*pageSize;}publicPage(RowBoundsrowBounds,booleancount){this(rowBounds,count?Page.SQL_COUNT:Page.NO_SQL_COUNT);}publicPage(RowBoundsrowBounds,inttotal){super(rowBounds.getLimit()>-1?rowBounds.getLimit():0);this.pageSize=rowBounds.getLimit();this.startRow=rowBounds.getOffset();//RowBounds方式默認(rèn)不求count總數(shù)，如果想求count,可以修改這里為SQL_COUNTthis.total=total;this.endRow=this.startRow+this.pageSize;}publicListgetResult(){returnthis;}publicintgetPages(){returnpages;}publicvoidsetPages(intpages){this.pages=pages;}publicintgetEndRow(){returnendRow;}publicvoidsetEndRow(intendRow){this.endRow=endRow;}publicintgetPageNum(){returnpageNum;}publicvoidsetPageNum(intpageNum){this.pageNum=pageNum;}publicintgetPageSize(){returnpageSize;}publicvoidsetPageSize(intpageSize){this.pageSize=pageSize;}publicintgetStartRow(){returnstartRow;}publicvoidsetStartRow(intstartRow){this.startRow=startRow;}publiclonggetTotal(){returntotal;}publicvoidsetTotal(longtotal){this.total=total;if(this.pageSize>0){this.pages=(int)(total/this.pageSize+((total%this.pageSize==0)?0:1));}else{this.pages=(int)total;}}publicbooleanisCount(){returnthis.total>NO_SQL_COUNT;}@OverridepublicStringtoString(){return"Page{"+"pageNum="+pageNum+",pageSize="+pageSize+",startRow="+startRow+",endRow="+endRow+",total="+total+",pages="+pages+'}';}}這是一個分頁類,我想增加兩個屬性:privateintnextPage;privateintpreviousPage;自定義一個類來繼承:publicclassPagePlusextendsPage{privateintnextPage;privateintpreviousPage;publicPagePlus(intpageNum,intpageSize){super(pageNum,pageSize);this.nextPage=super.getPageNum()+1;this.previousPage=super.getPageNum()-1;}publicintgetNextPage(){returnnextPage;}publicvoidsetNextPage(intnextPage){this.nextPage=nextPage;}publicintgetPreviousPage(){returnpreviousPage;}publicvoidsetPreviousPage(intpreviousPage){this.previousPage=previousPage;}}程序中是這樣寫的:@OverridepublicPagePluslist(intpageNum,intpageSize){PageHelper.startPage(pageNum,pageSize);PagePluspage=(PagePlus)articleDao.list();returnpage;}articleDao.list返回的是Listjava.lang.ClassCastException:com.github.pagehelper.Pagecannotbecasttoutil.PagePlus請問是哪里寫的有問題?