Java

Workaround:Manually set the MaxPermSize size, if it is a Linux system, modify the tomcat_home/bin/catalina.sh, if it is a Windows system, modify tomcat_home/bin/Catalina.bat,  Add the following line to the "echo" Using catalina_base: $CATALINA

UDP is mainly used in Java Datagramsocket to achieve communication, data is generally encapsulated through datagrampacket;The sender only needs to specify the address and port of the receiver, and then through the Send () method can be encapsulated

http://bbs.csdn.net/topics/390000725Summarize:equals before the rewrite and = =, after rewriting, equals as long as the content is trueequals = = is generally equivalent, but for string types, it overrides the Equals method and compares the contents.

Reference: http://my.oschina.net/gao0516/blog/136103Adorner mode: the ability to dynamically extend an object without having to change the original class file and use inheritanceAdapter mode: Transforms the interface of a class into another

Ok before said the reflection and reflection analysis of Java class, then these things have a horse effect, the following applications:Iii. using reflection to analyze objects at run time Simply write aEmployeeClass, then use java reflex to take

Tokens in Java generics mean:E -Element (used in the collection because the element is stored in the collection)T -type (Java Class)K -Key (key)V -value (values)N -Number (numeric type)? -Represents an indeterminate Java typeS, U, V -2nd, 3rd, 4th

1. Spin LockA spin lock is implemented in a loop in which the current thread is continuously executing, and can enter the critical section when the condition of the loop is changed by another thread. As followspublic class SpinLock { private

Records a method used to determine whether the characters in a string are all letters public class MainClass {public static void Main (string[] args) { String str = " Hhhggdxszfff "; Boolean is_boolean = Isphonticname

The difference between equals and = = in Javathe data types in Java can be divided into two categories:1. Basic data type (also known as raw data type): Byte,short,char,int,long,float,double,boolean, the comparison between them,double equals (= =)

1, Integer.min_value Save the minimum value of type int2, Integer.,ax_value Save the maximum value of type int3, int integer.parseint (string sinteger) converts an integer of type string to data of type int4, string integer.tobinarystring (int value)

Java is a simple, fully object-oriented, distributed, interpretive, secure and system-independent, portable, high-performance, multi-threaded, and dynamic programming language.Java is a cross-platform programming, Java Platform

Packagetest;Importjava.io.IOException;ImportOrg.apache.commons.httpclient.Cookie;Importorg.apache.commons.httpclient.HttpClient;Importorg.apache.commons.httpclient.HttpException;ImportOrg.apache.commons.httpclient.methods.GetMethod; Public

Let's start by describing what a map is. In the array we index the content by the array subscript, and in the map we index the object by object, the object to index is called key, and its corresponding object is called value. This is what we call a

Reference: https://www.ibm.com/developerworks/linux/library/j-zerocopy/This article describes the Zerocopy technology to improve the performance of IO-intensive Java applications on Linux platforms.Zerocopy technology avoids redundant data

1.MAP OverviewMap and collection exist to hold data that has a mapping relationship : Key-valueboth the key and value in the MAP can be data of any reference typethe key in the map is stored with set and does not allow repetition , so the set type

JAVA multi-thread and concurrency knowledge point summary 1. What are processes and threads? What is the difference between a thread and a process? 1. ProcessWhen a program runs in the memory, it becomes a process. A process is a running program.A

Implementation of multi-state factory-factory method modeOverview of factory method ModesIn the factory method mode, a unified factory class is no longer provided to create all product objects, but different factories are provided for different

Implementation of centralized factory-simple factory ModelOverview of simple factory models First, the code of the various objects to be created is encapsulated into different classes. These classes are called specific product classes, abstract and

Hibernate Session usage Session: used to perform persistent addition, deletion, query, modification, and interaction with the database. The Session object is non-thread-safe. SessionFactory: used to initialize Hibernate. Act as the proxy for the

Primary key attributes of Hibernate You can directly query the api documentation when these attributes are used. However, api documentation may be difficult for beginners who have no experience.This section describes how to generate the primary key