java character wrapper class

Java provides a total of eight basic data types, namely: Byte,short,int,long,float,double,boolean,char. Their corresponding packaging classes are in the Java.lang package, respectively, corresponding to: Byte,shortInteger,long,float,double,boolean,character.When you have to use objects or reference data types in some places (collection classes), the basic data types cannot be used because their storage principles and reference data types are completel

1. In different ways, the base type does not apply the new keyword, and the wrapper type needs to use the New keyword to allocate storage space in the heap;2. Different storage methods and locations, the basic type is to store the value of the variable directly on the stack, and the wrapper type is to put the object in the heap, and then by reference to use;3. Different initial values, the initial value of

1. The wrapper class object is immutable.2.==, when the wrapper class and the basic type use = = comparison, the packaging class will be automatically disassembled for the basic type and then compare3. Boolean,byte,char that is less than or equal to fixed-address

1, an overview of the integerRequirement 1: put 100 binary, octal, hexadecimal calculation of this dataRequirement 2: Determine whether a data is within the range of int.First you need to know how big the int is?In order to perform more operations on the basic data types and to operate more conveniently, Java provides the corresponding class type for each of the basic data types. The

the complex inheritance of the C + + developers have also brought greater trouble, in order to avoid the risk, Java only allow single inheritance, There can be only one parent class, but you can implement the same interface for multiple classes.Conversion is a relationship that must first be judged whether it is a parent, a subclass, and the parent-child class i

Packing class:Conversions between basic types and wrapper classesBoxing: The basic type is converted into a wrapper class, so that it has the nature of the object, but also can be divided into manual boxing and automatic boxing.int i=10;Integer x=new integer (i); Manual BoxingInteger y=i; Automatic BoxingUnpacking: In contrast to boxing, the

Question: Why do I need a wrapper class?The wrapper class value is the base data type, because the base data type cannot create the object and call the method, and the package wrapper class is available. For example, common data t

Instantiation of wrapper classesAll the packaging classes are immutable.Instantiation method:Construction methodIn addition to the character class, other packagesInteger (int x)Integer (String x)NumberFormatException exceptionThe parameters for the Boolean constructor method are not distinguishedUppercase and lowercaseTwo construction methods are provided for the

%linux_wrapper_home%/lib, the pre-packaged project Jar package is also placed here.9. Upload the%wrapper_home%/src/bin/sh.script.in file to the%linux_wrapper_home%/bin directory and rename it as (recommendation: the class name of the main method in the Java project). Open the file and modify two places:App_name= "Enter your project name"App_long_name= "Enter your project name".10, open the%linux_wrapper_hom

Topic: integer i = 42 long l = 42l; double d = 42.0 The following is trueA. (i = = L)B. (i = = d)C. (L = = d)D.i.equals (d)E.d.equals (L)F.i.equals (L)G.l.equals (42L)Answer: Gparsing:Comparisons of the same type, such as Integer and Int,long, are automatically removed when compared with long = =, and are compared between different types, and if one is a non-wrapper class, the box is a

1, guess the number of small games Packagecn.jiemoxiaodi_02;ImportJava.util.Scanner;/*** Guess number games * *@authorHuli **/ Public classGuessnumberdemo { Public Static voidMain (string[] args) {intNumber = (int) (Math.random () * 100) + 1; while(true) {System.out.println ("Please enter the number you guessed:"); String Line=NewScanner (system.in). nextline (); intValue =Integer.parseint (line); if(Number >value) {System.out.println ("Your guess is small."); } if(Number = =value) {