Java

JDBC type Java type CHAR string VARCHAR string LongVarChar Strin G NUMERIC java.math.BigDecimal DECIMAL java.math.BigDecimal BIT Boolean Boolean Boolean TINYINTbyteSMALLINT

1. Practical significanceIn real-world development, if you need to do a float or double accurate calculations (especially financial calculations ), it is not possible to use float or double directly (see the test results of the main method of the

If the values of the Char,byte or short type are shifted, they will be converted to the int type before the shift is made.and the resulting result is also an int type.If the value of long is processed, the result is long.If this right-shift (>>>=)

Internationalization: So that everyone in the world can read it.Locale Class (under Java.util package): Includes all countries, regions, languagesThere are many static properties that represent the country, languageThree methods of

Thread Status DescriptionThe thread state is defined in the Thread.state enumeration, and the following is taken from the Thread.java sourceNEW:Thread has not startedA thread that has not yet started are in this state.RUNNABLE:Thread can run, but

UUID: Universal Unique identification:universally unique Identifier; A number generated on a machine that guarantees that all machines in the same time and space are unique. The GUID is a 128-bit long number, typically represented by a 16 binary.

Question one:The difference between null and ""String S=null;S.trim () will throw an empty exceptionString s= "";S.trim () will not throw, why?For:A null representation declares an empty object and is not a string at all."" represents an instance of

In the JVM specification, each type has its own constant pool. Chang is an ordered set of constants used by a type, including direct constants (primitive types,String), and symbolic references to other types, fields, and methods. A symbolic

Long time No read Java network programming, and now just the company has the opportunity to contact, the way to pick up the previous thingsRefer to the original blog: http://www.cnblogs.com/linzheng/archive/2011/01/23/1942328.htmlFirst, network

1, to finalize the understanding:The finalize- method name. is part of the operating mechanism of the GC operation, and the Finalize method is called when the GC operation is performed. Java technology allows use Finalize () method to do the

in real life, rice cookers can achieve the function of "cooking rice", but only if we have to provide ingredients. If we don't offer anything, it's really "paddle". Java with parameters is a way to solve this kind of problem.For example, in order

Storage allocations for Java programs in memory:Heap Area:1. All objects are stored, each containing a class-corresponding information. (The purpose of class is to get operation instructions)2.JVM only one heap area (heap) is shared by all threads,

one Java polymorphic Polymorphism is the ability of the same behavior to have many different manifestations or forms. Polymorphism is the embodiment of multiple forms of objects. Like we said, "PetObject, it has a lot of different expressions or

a Java Bundle (package) To better organize classes, Java provides a package mechanism for distinguishing the namespace of a class name.The role of the package:A a function similar or related classes or interfaces organized in the same package,

Package com.util; Import Java.io.File; /** * Directory Processing Tool class * */ Public class Dealwithdir { /**  * New Directory */ public Static boolean newdir (String path) throws Exception { File File = new file

Ava writes something to read the data in TXT and to calculate the average and the total value to be sorted by the total value.Java writes something to read the data in TXT and to calculate the average and the total value to be sorted by the total

I found a very strange problem when debug was chasing the stack.I use IE8 and Google's browser to access the same addressThe action's scope= "session" also sets theand two browser-submitted parameter map is also independent of each otherBut it's

One, the difference between Java io and NiO:(1) Java NIO provides different IO modes of operation than standard IO: Channels and Buffers (channels and buffers): Standard IO is based on byte stream and character stream, while NiO is based on

Tomcat's JSP Engine and tomcat JSP Engine The jasper component of tomcat must be used to parse jsp files into class files.Jasper is the JSP Engine Used in tomcat, and Jasper 2 is used in Tomcat 6. Compared with the original version, Jasper has made

Spring Boot MyBatis connects to the database Recently busy, did not have time to extract the integration of MyBatis out, in fact, mybatis official website in late November 2015 has released the SpringBoot integrated Release version, Github has code: