java.lang.NullPointerException: element cannot be mapped to a null key 报错

 

 

这行代码 getSupplierLoginId 可为空时会报这种错误

Map<String, List<PurchaseOrderEntity>> collect = purchaseOrderEntities.stream().collect(Collectors.groupingBy(PurchaseOrderEntity::getSupplierLoginId));

代码修改后对空值进行过滤：

Map<String, List<PurchaseOrderEntity>> collect = purchaseOrderEntities.stream().filter(item-> StringUtil.isNotBlank(item.getSupplierLoginId())).collect(Collectors.groupingBy(PurchaseOrderEntity::getSupplierLoginId));