JDK 8 中Stream流中去重的方法
1.简单的去重,可以使用distinct()方法去重,该方法是通过比较equals和hashcode值去去重,
2.复杂的去重,
例如,在一个JavaBean的集合中,去除某个属性重复的对象
@Override
public List<RptDayMonthTargetVO> queryTarget() {
List<RptDayMonthTarget> list = targetService.selectMonthTarget();
//数据去重-根据Bean对象的SupplierId属性去重
List<RptDayMonthTarget> dbList = list.stream().filter(distinctByKey(RptDayMonthTarget::getSupplierId)).collect(Collectors.toList());return voList;
}
private static <T> Predicate<T> distinctByKey(Function<? super T, ?> keyExtractor) {
Map<Object,Boolean> seen = new ConcurrentHashMap<>();
return t -> seen.putIfAbsent(keyExtractor.apply(t), Boolean.TRUE) == null;
}
