Client (Client) Conceptual Server of Server: Generally, Server Different (Hardware Server, Software Server) Hardware Server: Refers to a relative PC, performance and stability are better, using special Hardware computer. Software Server: It is a popular saying that a service software is installed and a machine that provides the corresponding service, we call it a server. Service software has many kinds, common: WWW services software: PWS, IIS, Apachej2ee middleware application server: WebSphere, SilverstreamJSP engine (weak WWW service): Tomcat, Resin, WebLogic, JRunsmtp, POP3: IIS SMTP , Exchange, Lotus DominoftP: IIS comes with the client: Relative to the server, it is a party to enjoy some kind of service, called the client. But if you want some kind of service, you must install the appropriate software, such as (IE / Netscape, Outlook / Foxmail, Cuteftp)
The basic type of data type has the following four: INT length data types are: Byte (8bits), short (16bits), int (32bits), long (64bits) Float length data type is: single precision (32bits float), double precision ( The value of the 64bits DoubleBoolean type variable is: Ture, Falsechar Data types are: Unicode characters, 16-bit Category Category: Integer, Float, Boolean, Character, Double, Short, Byte, Long
Conversion Principle: Transition from low-precision to high precision Byte, Short, Int, long, Float, Double, CHAR Note: When two CHAR type operations are automatically converted to an INT type; when char and other types of types, Automatically convert to int type, then do other types of automatic conversion
Basic Type To Class Type Conversion Positive Conversion: By Class Package NEW Outsorit A New Class Type Variable Integer A = New Integer (2); Reverse Conversion: Convert INT B = A.intValue by class wrapper. );
Class Type to String Conversion Positive Conversion: Because each class is a subclass of the Object class, all Object classes have a toString () function, so reverse conversion through the toString () function: pass Class wrapper New outgoing variables of a new class type EG1: I = INTEGER.VALUEOF ("123"). INTVALUE () Description: The above example is converting a string into an Integer object, then call this object The INTVALUE () method returns its corresponding INT value. EG2: float f = float.valueof ("123"). FLOATVALUE () Description: The above example is converting a string into a float object, and then call the FLOATVALUE () method of this object returns its corresponding float value. EG3: Boolean B = Boolean.Valueof ("123"). BooleanValue () Description: The above example is converting a string into a Boolean object, and then call the BooleanValue () method of this object returns its corresponding Boolean value. EG4: DOUBLE D = Double.Valueof ("123"). DoubleValue () Description: The above example is converting a string into a Double object, and then call the DoubleValue () method of this object returns its corresponding Double value. Eg5: long l = long.valueof ("123"). LongValue () Description: The above example is converted a string into a long object, then call the longValue () method of this object returns its corresponding long value. EG6: Char = Character.Valueof ("123"). CHARVALUE () Description: The above example is converting a string into a CHARACTER object, and then call the CHARVALUE () method of this object returns its corresponding char value.
