• <ins id="pjuwb"></ins>
    <blockquote id="pjuwb"><pre id="pjuwb"></pre></blockquote>
    <noscript id="pjuwb"></noscript>
          <sup id="pjuwb"><pre id="pjuwb"></pre></sup>
            <dd id="pjuwb"></dd>
            <abbr id="pjuwb"></abbr>

            M-A-T Tory's Blog

              C++博客 :: 首頁 :: 新隨筆 :: 聯(lián)系 :: 聚合  :: 管理 ::
              16 隨筆 :: 1 文章 :: 1 評論 :: 0 Trackbacks

            Where storage lives

            It’s useful to visualize some aspects of how things are laid out while the program is running—in particular how memory is arranged. There are six different places to store data: Feedback

            1. Registers. This is the fastest storage because it exists in a place different from that of other storage: inside the processor. However, the number of registers is severely limited, so registers are allocated by the compiler according to its needs. You don’t have direct control, nor do you see any evidence in your programs that registers even exist. Feedback
            2. The stack. This lives in the general random-access memory (RAM) area, but has direct support from the processor via its stack pointer. The stack pointer is moved down to create new memory and moved up to release that memory. This is an extremely fast and efficient way to allocate storage, second only to registers. The Java compiler must know, while it is creating the program, the exact size and lifetime of all the data that is stored on the stack, because it must generate the code to move the stack pointer up and down. This constraint places limits on the flexibility of your programs, so while some Java storage exists on the stack—in particular, object references—Java objects themselves are not placed on the stack. Feedback
            3. The heap. This is a general-purpose 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 compiler 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 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++). Feedback
            4. 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. Feedback
            5. 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 read-only memory (ROM), in embedded systems. Feedback
            6. Non-RAM storage. If data lives completely 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 RAM-based object when necessary. Java provides support for lightweight persistence, and future versions of Java might provide more complete solutions for persistence. Feedback
            posted on 2006-04-20 22:40 Tory 閱讀(123) 評論(0)  編輯 收藏 引用 所屬分類: Java Learning
            久久国产视频99电影| 狠狠综合久久综合中文88| 国产一级持黄大片99久久| 久久综合亚洲色HEZYO社区| 精品久久人人妻人人做精品| 久久久青草青青亚洲国产免观| 久久人人妻人人爽人人爽| 精品久久久久久成人AV| 69久久精品无码一区二区| 久久99国产精品一区二区| 99久久精品久久久久久清纯| 狠狠色丁香久久婷婷综合_中| 日本久久久久久久久久| 一本色道久久综合狠狠躁篇| 中文国产成人精品久久不卡| 久久国产免费观看精品| 狠狠久久综合| 久久天天躁狠狠躁夜夜不卡| 麻豆成人久久精品二区三区免费 | 国产精品99久久久久久猫咪| 欧美大战日韩91综合一区婷婷久久青草| 久久人人爽人爽人人爽av| 久久婷婷激情综合色综合俺也去 | 94久久国产乱子伦精品免费| 久久人人爽人人爽人人片AV麻豆 | 久久免费大片| 2021久久国自产拍精品| 亚洲?V乱码久久精品蜜桃| 久久水蜜桃亚洲av无码精品麻豆 | 色婷婷综合久久久久中文一区二区| 99久久精品日本一区二区免费| 四虎国产精品免费久久5151| 久久无码AV中文出轨人妻| 亚洲国产精品久久久久婷婷软件| 精品久久久久成人码免费动漫| 国产精品久久久天天影视| 色婷婷久久久SWAG精品| 久久国产高清字幕中文| 亚洲∧v久久久无码精品| 亚洲精品国产第一综合99久久| 无码人妻少妇久久中文字幕|