tailieunhanh - Thinking in Java 3rd Edition phần 2

đối tượng, trong đó đối tượng được chuyển thành dòng byte, thường được gửi đến máy khác và các đối tượng liên tục, trong đó các đối tượng được đặt trên đĩa, do đó họ sẽ tổ chức nhà nước của họ ngay cả khi chương trình được chấm dứt. | 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 Special case primitive types One group of types which you ll use quite often in your programming gets special treatment. You can think of these as primitive types. The reason for the special treatment is that to create an object with new especially a small simple variable isn t very efficient because new places objects on the heap. For these types Java falls back on the approach taken by C and C . That is instead of creating the variable using new an automatic variable is created that is not a reference. The variable holds the value and it s placed on the stack so it s much more efficient. Feedback Java determines the size of each primitive type. These sizes don t change from one machine architecture to another as they do in most languages. This size invariance is one reason Java programs are portable. Feedback Primitive type Size Minimum Maximum Wrapper type boolean Boolean char 16-bit Unicode 0 Unicode 216- 1 Character byte 8-bit -128 127 Byte short 16-bit -215 215 1 Short int 32-bit -231 231 1 Integer long 64-bit -263 263 1 Long float 32-bit IEEE754 IEEE754 Float double 64-bit IEEE754 IEEE754 Double void Void Chapter 2 Everything is an Object 89 All numeric types are signed so don t look for unsigned types. Feedback The size of the boolean type is not explicitly specified it is only defined to be able to take the literal values true or false. Feedback The wrapper classes for the primitive data types allow you to make

TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.