null adj. 1.无效力的,无束缚力的。 2.无效的,无用的,无益的;无价值的。 3.没特征[个性]的,没表情的。 4.〔罕用语〕不存在的,没有的;零(位)的;空的。 n. 【数学】零,零位;空;【无线电】零讯号,微弱讯号。 a null indicator 零示器;零位指示器。 the null method 衡消法。 null and void 【律】无效;失效(This check is null and void. 本支票无效)。 vt. 使无效。
Is thrown when an attempt is made to invoke a non-static method on a null object 当尝试对空对象调用非静态方法时,将引发
The exception that is thrown when there is an attempt to dereference a null object reference 尝试取消引用空对象引用时引发的异常。
This provides the flexibility in type system design to map null objects to their corresponding xml types 这就为类型系统设计提供了将空(null)对象映射为其对应的xml类型的灵活性。
Transfers control if it represents an instance of an object for example, if it is not the null object reference; see 的别名)将在它表示对象实例时转移控制(例如,在它不是空对象引用时;请参见
However, this case-where a class manages its own memory-is one of the very few situations where explicitly nulling objects that are no longer needed is a good idea 但是这种情况由类管理其自己的内存是一种非常少见的情况,即显式地消除不再需要的对象是一个好主意。
The conventional way to have a reference refer to no-object is to provide an explicit singleton representing by convention a null object which often serves as a default argument to a function parameter (让引用引用空对象的常规方式是提供显式的单一实例,按约定,该实例表示一个经常充当函数参数的默认变量的空对象)。