Optional.ofNullable(参数1).orElse(参数2)

Posted 2022-12-09 ITdfq

• Optional.ofNullable(参数1).orElse(参数2)
  判断参数1 是否为空，不为空，则赋值，为空则赋值参数2，避免了空指针异常

     public static void main(String[] args) 
          List<String> lists = null;
          List<String> list = new ArrayList<String>();
          list.add("你好");
          list.add("hello");
          List<String> newList = Optional.ofNullable(list).orElse(lists);
          newList.forEach(x -> System.out.println(x));
  
          System.out.println("-------------------");
          List<String> list1 = null;
          List<String> list2 = new ArrayList<String>();
          list2.add("你好");
          list2.add("hello");
          List<String> newList2 = Optional.ofNullable(list1).orElse(list2);
          newList2.forEach(x -> System.out.println(x));
      
  

  结果：