会被打印出来,而后边一句会打印出null,我们知道println一般是调用对象的toString来进行打印,但是null明显不是对象,作为一个不确定引用它只是把自己的literal给打印了出来,因此我猜测null是预先存储在内存中的一个引用,它是有值的,可能根据不同的jvm有不同的实现,但是jvm中会一致地将这个值打印为null。郑州建站推广 网站策划 网站
The null keyword in Java is a literal that represents a null reference, one that points to no object. It is often used to indicate that a reference variable does not currently refer to any object or that a method has no return value. Usage The null keyword can be assigned to any refere...
Java中,null是一个关键字,用来标识[color=red]一个不确定的对象[/color]。因此可以将null赋给引用类型变量,但不可以将null赋给基本类型变量。 比如:int a = null;是错误的。Ojbect o = null是正确的。 Java中,变量都遵循一个原则,先定义,并且初始化后,才可以使用。我们不能int a后,不给a指定值,就去打印...
不是关键字。true，false， null 都不是。null is a literal, in the same sense that false, 10, and '\n'are literals. It's not a "keyword", technically, but it is a character string that is treated specially by the compiler if the compiler encounters it in a java source ...
4.In practice, the programmer can ignore the null type and just pretend that null is merely a special literal that can be of any reference type. 注:其实,程序开发者可以忽略 null 类型,仅仅将它当作一种可以赋值给其他任意类型的特殊引用。
* `Null` is the type of the `null` literal. It is a subtype of every type * except those of value classes. Value classes are subclasses of [[AnyVal]], which includes * primitive types such as [[Int]], [[Boolean]], and user-defined value classes. ...
不是关键字。true，false， null 都不是。null is a literal, in the same sense that false, 10, and '\n'are literals. It's not a "keyword", technically, but it is a character string that is treated specially by the compiler if the compiler encounters it in a java source ...
literals = {LiteralKind.NULL}, typeNames = {java.lang.Void.class} ) @DefaultInUncheckedCodeFor({TypeUseLocation.RETURN, TypeUseLocation.UPPER_BOUND}) public @interface Nullable {} 下面两个包没有@Nullable,所以单独列出来;龙目岛有一个很无聊的@NonNull。在javax.validation.constraints@NonNull实际上是...
* `Null` is the type of the `null` literal. It is a subtype of every type * except those of value classes. Value classes are subclasses of [[AnyVal]], which includes * primitive types such as [[Int]], [[Boolean]], and user-defined value classes. ...
The null reference is the only possible value of an expression of null type.The null reference can always be assigned or cast to any reference type. In practice, the programmer can ignore the null type and just pretend that null is merely a special literal that can be of any reference ...