Java如何为构造函数中声明的对象和变量命名的对象分配不同的内存？

Question

Using Java IO streams, it is quite often we use objects solely as constructors for other objects. I am interested in the memory implications of this prospect. For example, how does memory allocation differ in these two statements that do the same thing?

FileInputStream inputFile = new FileInputStream("filepath");
Scanner inStream = new Scanner(inputFile);

and

Scanner inStream = new Scanner(new FileInputStream("filepath"));

Answer 1

The first one will allocate a named variable in the current stack frame. On the heap, there is no difference - or there shouldn't be but the VM is of course free to optimize the code in some way as long as the rules are obeyed.

Answer 2

没有区别。两者都是一样的。

Answer 3

在第一个示例中，JVM保留对FileInputStream的引用，而在第二个示例中，JVM创建一个未引用的对象，该对象准备在执行该语句后进行垃圾收集。