java8-排序

• list

  • 升序

    //第一種
    list.sort((a,b)->a.getSeqNo().compareTo(b.getSeqNo()));
    //第二種
    list.sort(Comparator.comparing(TransportationPriceAdvance::getFristWeight));
    //第三種 ==》排序後返回一個新的list
    List<Object> specialProducts =list.stream().sorted((u1,u2)->u1.getSpecialProduct().compareTo(u2.getSpecialProduct())).collect(Collectors.toList());
    

  • 降序

    //第一種
    entry.getValue().sort((a,b)->b.getSeqNo().compareTo(a.getSeqNo()));
    //第二種
    list.sort(Comparator.comparing(TransportationPriceAdvance::getFristWeight).reversed());
    //第三種 ==》排序後返回一個新的list
    List<Object> specialProducts =list.stream().sorted((u1,u2)->u2.getSpecialProduct().compareTo(u1.getSpecialProduct())).collect(Collectors.toList());
    

• map

  comparingByValue().reversed倒序，不指定類型，會默認爲<java.util.Map.Entry<java.lang.Object,V>>

  • 升序

    map.entrySet().stream()
     .sorted(Map.Entry.<String, Integer>comparingByValue())  
    	.forEachOrdered(x -> result.put(x.getKey(), x.getValue()));
    

  • 降序

    map.entrySet().stream()
     .sorted(Map.Entry.<String, Integer>comparingByValue().reversed())  
    	.forEachOrdered(x -> result.put(x.getKey(), x.getValue()));