java畢業(yè)設計外文文獻原文及譯文-在線瀏覽
2025-01-26 03:19本頁面
【正文】 is a generalpurpose pool of memory (also in the RAM area) where all Java objects live. The nice thing about the heap is that, unlike the stack, the piler doesn’t need to know how much storage it needs to allocate from the heap or how long that storage must stay on the heap. Thus, there’s a great deal of flexibility in using storage on the heap. Whenever you need to create an object, you simply write the code to create it by using new, and the storage is allocated on the heap when that code is executed. Of course there’s a price 第 4 頁 共 7 頁 you pay for this flexibility. It takes more time to allocate heap storage than it does to allocate stack storage (if you even could create objects on the stack in Java, as you can in C++). Static storage. “Static” is used here in the sense of “in a fixed location” (although it’s also in RAM). Static storage contains data that is available for the entire time a program is running. You can use the static keyword to specify that a particular element of an object is static, but Java objects themselves are never placed in static storage. Constant storage. Constant values are often placed directly in the program code, which is safe since they can never change. Sometimes constants are cordoned off by themselves so that they can be optionally placed in readonly memory (ROM), in embedded systems. NonRAM storage. If data lives pletely outside a program, it can exist while the program is not running, outside the control of the program. The two primary examples of this are streamed objects, in which objects are turned into streams of bytes, generally to be sent to another machine, and persistent objects, in which the objects are placed on disk so they will hold their state even when the program is terminated. The trick with these types of storage is turning the objects into something that can exist on the other medium, and yet can be resurrected into a regular RAMbased object when necessary. Java provides support for lightweight persistence, and future versions of Java might provide more plete solutions for persistence One group of types, which you’ll use quite often in your programming, gets special treatmen
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