java constants class

In Java, data is stored and represented in the form of constants and variables (in fact, all the data for the program are in both of these forms).variablesThe variable represents the state of the program. The program changes the value of the variable to change the state of the whole program, or more, that is, the implementation of the program's functional logic.In order to conveniently reference the value o

Source: http://www.imooc.com/code/1256The so-called constant, which we can understand as a special variable, whose value is set, is not allowed to change during program Operation .Syntax:final constant name = value;Using Constants in your program can improve the maintainability of your code. For example, in project development, we need to specify the user's gender, at this time can be defined as a constant sex, assigned to "male", in the need to speci

In actual work development, we often use constants.Constants we commonly use, for example: publicstatic final int age_of_person =; Naming rules for constants: All words are capitalized, and if there are multiple words, use an underscore to connect.When you declare a final constant in Java , you add the static keyword, which is why? Since it is final and immutable, there is no need to declare a variable for

Meow Meow Drive, Novice Road, a lot of care. Any errors please indicate in the comment area............................................ I am the dividing line of evil (??ω??)? .........................................Final: Used to modify classes, variables, methods:The final decorated class cannot have subclasses, nor can it be inherited.The final modified variable is a constant and cannot be re-assigned.The final decorated method cannot be overridde

initialized (assigned) before they can be used, and initialization is the true memory allocation.Iii. Classification of variables-scope-usage rules　　1. Classification of variables　　　　Variables fall into two categories depending on the location of the definition　　　　　1) member variables/fields: variables directly defined in the class {} (outside the method)2) Environment variables: variables other than member variables, variables defined in the method　

In the process of program execution, the amount whose value cannot be changed is called a constant, and the amount of its value can be changed is called a variable. I'll use the following code to introduce identifiers and keywords, variables and constants (///,/* These two symbols represent comments):Public class test{//Create Class/** * Identifier: The so-calle

Final (final) is a modifier1, final can be modified classes, functions, variables (member variables, local variables)2, the final modified class can not be inherited by other classes3, the final modified method (function) can not be rewritten4, the final modified variable (attribute) is not allowed to be re-assigned, final in the modification of the variable must be assigned, the final modified variable, we call the constantDefine

When we write Java programs, we often have constant settings, such as:　　1 Public InterfaceConst {2 3 //Constants of gender4 Public Interfacesex{5 Public Final intMale =1;//male6 Public Final intfemale = 2;//female7 }8 9}This setting method publishes constants out of the interface. But there are shortcomings. It does not help wi

New Package : Upper left corner-new-PackageNaming conventions (usually from large to small, easy to integrate and not easy to conflict) For example: Com.itnba.maya.testThe package must be in the top row, and no more code can beUsing packages:Shortcut: Use a variable name in the package alt+/Import package name. class name; Reference only one of the import package names in the package. *; Refer to all examples in the package import com.itnb

+ "B"; S1 is a variable, "B" is a constant, variable + constant! = constant, so it does not enter the pool.Once in the pool, you will find the object in the pool first. If this object is available, the object reference is directed to the object, and if there is none, the object is created first, and then the object reference points to the object.Cases:String S5 = "ABC"; Find the "ABC" object in the pool first, and if so, let S5 point to the object, or if there is no "ABC" object in the pool, cr

Variables | syntax 1. Variable: Definition: believe that the definition of it should not be said, we should have been familiar with the familiar. For example: A,a1,name and so on are all valid variables. Description 1 Java requires that the type of the variable be declared before using a variable. 2 the declaration of a variable in Java is a complete Java stateme

FRIDAY = "FRIDAY";private static final String SATURDAY = "SATURDAY";public static String Getsunday () {return SUNDAY;}public static String Getmonday () {return MONDAY;}public static String Gettuesday () {return Tuesday;}public static String Getwednesday () {return Wednesday;}public static String Getthursday () {return Thursday;}public static String Getfirday () {return FRIDAY;}public static String Getsaturday () {return SATURDAY;}}public class Testco

in the corresponding wrapper class in the form of constants. Public classPrimitivetypetest { Public Static voidMain (string[] args) {//byteSystem.out.println ("base type: Byte bits number:" +byte.size); System.out.println ("Packing class: Java.lang.Byte"); System.out.println ("min: byte.min_value=" +byte.min_value); System.out.println ("Maximum value: byte.max_v

result is: 82.0 This conversion is calledAutomatic type conversionOf course automatic type conversion is requiredmeet a specific conditionOf: ①target type compatible with source type, such as type double compatible int, but char type is not compatible with int typeThe ② target type is greater than the source type, such as a double type of 8 bytes and an int type of 4 bytes, so a variable of type double can directly hold data of type int, but not in turn.2-8 forced type conversions in JavaSyntax

ObjectiveFirst look at the following code results what is it?Package Cn.demo_01;public class StringDemo02 {public static void main (string[] args) {String a = "abc"; String B = "AB"; String c = "C"; System.out.println (A = = B + c);}}What is the result of looking at this code?Package Cn.demo_01;public class StringDemo02 {public static void main (string[] args) {String a = "abc"; System.out.println (A = = "A

. println (A = = c);//falseA, B is determined at compile time, and C is a reference variable and is not determined at compile time.Application: Recommended in peacetime use, try to use string = "ABCD", this way to create a string, rather than string = new string ("ABCD"), this form, because using the new constructor to create a string object will certainly open up a new heap space , while double quotes are optimized using string interning (String dwell), which is much more efficient than the con

--> --> java Interface is the best place for constant storage? !--Black line separator--> The!--end HEADER area--> The!--start body area--> the!--Sidebar gutter-->!--START toc--> java/l-java-interface/index.shtml# Author1 ">bright (brightsee@21cn.com) !--Author name (email address) [title], [Company] 2001 x month --> Because The fields declared in the

First, the concept of package: Create, use.1. New Package:In the top row, no more code can be found before.Package name;Note: The package name generally has a named specification. For example: Com.itnba.maya.zy (from large to small).2. Use the package:Import package name. *;Import package name. class name;For example: Import com.itnba.maya.zy.*;Note: Import should not be placed on the top of the package Package Com.itnba.maya.zy; import com.itnba.maya

What is a constantIts value cannot be changed during program executionClassification of constants in JavaLiteral constantsCustom ConstantsClassification of literal constantsClassification of literal constantsThe contents of a string constant enclosed in double quotation marksinteger constant all integersDecimal constant All DecimalsCharacter constants are enclosed in single quotes, with only characters, sin

The definition of a constant: the amount of its value does not change (more precisely, it is not changeable) during the course of the program is called a constant.The function of constants: simple, intuitive description of a thing, is the basis of variables, is the basis of the program run.Constants are divided into two main categories: primitive values (which do not need to be defined), such as: (1, 2.1) numeric