Java8新特性之Optional类的使用

        //1、将可能为空的对象转换为Optional对象
//        LiabilityPayEntity liabilityPayEntity1 = null;
        LiabilityPayEntity liabilityPayEntity1 = LiabilityPayEntityBuilder.builder().setIsChecked("1").createLiabilityPayEntity();
        Optional<LiabilityPayEntity> optionalLiabilityPayEntity = Optional.ofNullable(liabilityPayEntity1);
        System.out.println("是否不为null："+optionalLiabilityPayEntity.isPresent());

        //2、Optional链式操作
        String isChecked = optionalLiabilityPayEntity.map(LiabilityPayEntity::getIsChecked).orElse("0");
        System.out.println("isChecked："+isChecked);

        //3、Optional短路
        //假设optionalLiabilityPayEntity对象从数据库中查询出来的，如果不存在则新建用户并返回
        //(1) 错误用法，orElse是不断路的，如果orElse中的执行是负影响的，会被执行。
        //LiabilityPayEntity liabilityPayEntity = optionalLiabilityPayEntity.orElse(newBean());
        //(2) 正确写法，如果对象为空，newBean不执行。
        LiabilityPayEntity liabilityPayEntity = optionalLiabilityPayEntity.orElseGet(() -> newBean());
        System.out.println("liabilityPayEntity != null："+(liabilityPayEntity != null));

        //4、Optional抛出异常
        optionalLiabilityPayEntity.orElseThrow(() -> new RuntimeException("对象为空！"));

        //5、Optional映射等一些其他的操作
        optionalLiabilityPayEntity.map(LiabilityPayEntity::getIsChecked)
                .filter(isChecked1 -> isChecked1.equals("1"))
                .ifPresent(isChecked2 -> System.out.println(isChecked2));


        private LiabilityPayEntity newBean(){
            System.out.println("我要创建对象啦！");
            return LiabilityPayEntityBuilder.builder().setIsChecked("9").createLiabilityPayEntity();
        }