can also be created directly by using polymorphic creation.Similarly, as a return value, although the implementation class object is passed in, it must be the interface type when it is received.Write a simple case for the above supplement to understand: public abstract class Animal { public abstract void Eat ( ); public static Animal getinstance () { return new Cat (); }} Public class extends Animal { publicvoid eat () { System.out.println ("cat is Eating");} } P
%, ArrayList.
ArrayList
2 Similarities and differences of Hashtable and HashMap
Collection
Same
Difference
Hashtable
The principle of implementation, the same function, can be interoperable.
Hashtable inherits the Dictionary class, HashMap implements the map interface.
Hashtable thread safety, HashMap thread non-secure
Hashtable does not allow null values, HASHMAP allows null values.
follows:Eventutil.addhandler (obj, ' click ', bind (Demo.show,demo));Four, function throttlingFor code that executes periodically, a function throttle should be performed.For example, the following scrolling event:function () { throttle (Demo,window); }When the page scrolls, it will continue to output the results. This high frequency response, if the method is more complex, will consume more performance. For this scenario, we can do the following optimizations:// setting and elimina
this:The contents of the 1/*stdio.h file will replace the location of # include The code becomes very concise and the output is:Third, Other uses1. Usage of #if defined () and # if!defined ()#if and #elif后面的条件不仅仅可以用来判断宏的值, you can also determine whether a macro has been defined. Like what:1 #if defined (MAX) 2 ... code ... 3 #endifIf you have already defined Max as a macro, compile code into it. It does not control the value of Max, as long as Max is defined, the condition is set.Conditions
: $PATHSOURCE ~/.profile, update environment variable 4. Results test input java-version, if prompted for Java version information, the installation is successful5. Summary of Commandssudo mkdir jvmsudo tar zxvf. /jdk-8u161-linux-i586.tar.gz -c/usr/lib/~/. Profileexport java_home=/usr/lib/jvm/jdk1. 8. 0_161export jre_home=${java_home}/jreexport CLASSPATH=.:${java_home}/lib:${jre_home}/ libexport PATH=${java_home}/~/6. Issues that may arise:(1) Program ' Java ' is included in the following pac
the tool to decrypt the BASE64 encryption decryptionGive us a bunch of code, flag, in the code.Enter password to view flagTopic Link http://120.24.86.145:8002/baopo/Because the topic link is temporarily not going to go, then updateViewed 1 million timesTopic Link http://120.24.86.145:9001/test/Open the page, ask us to click 1 million times, we look at the source code, see if we can start from the source code to solve the problemAfter we click some data will change, we try to change the next cli
= "Com.yiibai.customer.services.CustomerService" > class= "Com.yiibai.aop.HijackAroundMethod"/> class= "Org.springframework.aop.support.NameMatchMethodYiibaicutAdvisor" > Beanclass= "Org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator" > XmlNow, you can get the bean by the original name of "CustomerService", if you know that the bean has been proxied.= (CustomerService)appContext.getBean("customerService");Java2. defaultadvisorautoproxycreator ExampleThis DefaultAdvisorAutoProxy
responding when a class is treated as a string
__invoke (), called when a function is called in a way that responds to an object
__set_state (), this static method is called when the Var_export () export class is called.
__clone (), called when the object copy is complete
__autoload (), attempting to load an undefined class
__debuginfo () to print the required debug information
For more information, please see below:http://php.net/manual/zh/language.oop5.magic.phpExt.:
possible)2. Analysis reason: After slowly debugging found, when the "Save Settings" button, because of the previous select operation, lost focus3. Workaround: After the select operation, do a click () operations = driver.find_element_by_id ("NR")Select (s). Select_by_visible_text ("Show 20 per page")Time.sleep (3)S.click ()VI. Final code# Coding:utf-8From selenium import WebdriverFrom Selenium.webdriver.common.action_chains import ActionchainsFrom Selenium.webdriver.support.select Import Select
condition object to control the potential lock object.Wait () methodEquivalent to Cond_wait ()Notify_all ()Quite with Cond_broadcast ()Nofify ()Similar to the Notify_all () feature, but only wakes up a waiting thread, not allThreading. Semaphore ObjectSemaphore, which is the count lock. When creating an object, you can pass an integer as the upper limit of the count (Sema = threading. Semaphore (5)).It is similar to lock and has two methods for lock.Threading. Event ObjectWith threading. The co
);} } int main (int argc, char* argv[]) { handle_connections ();}It's very simple, and it's self-explaining. I leave the asynchronous UDP client and the server to the reader as an exercise.Summarize the applications that we have written to finish, and ultimately let Boost.asio work. Echo App is a great tool to start learning a library. You can often learn and run the code shown in this section so that you can easily remember the base of the library. In the next chapter, we'll build more
installation scriptImportant: Pull the installation script in the "~/" directory where the account is running .# 安装或升级gityum install git -y# 拉取安装脚本,注意脚本的保存目录cd ~git clone https://github.com/Netonline2016/k8s-ansible.git4. Download the installation packageIn order to avoid the installation process, the network download installation package time-out or wait too long, download the appropriate packages in advance, and placed in the corresponding path, this process has been organized into shell scri
exact matchTake a look at the following example (using the module we completed together previously Hello World ): location/poechant {Hello_world no1;} Location =/poechant {Hello_world no2;} If our request is http://my.domian/poechant , we found two location is matched to the requested URI, and according to our priority order, the first is an empty match when the exact match is matched, the second equals the match, so the second priority is high, which is the output: hello_world, no2It also i
wildcard character?? Extends E? Super E(5) Where do we use it?is used in the collection.3: Enhanced for loop (master)(1) is a For loop(2) formatFor (the element's data type variable name: An array or an object of the collection collection) {With this variable, the variable is actually the element in the set of number of members}(3) BenefitsSimplifies the traversal of arrays and collections(4) DisadvantagesThe target of the enhanced for loop cannot be nu11, and it is recommended to determine whe
? The entry for Spring MVC is the Servlet, and Struts2 is the Filter? Spring MVC will be slightly faster than Struts2. Spring MVC is based on method design, and Sturts2 is class-based, and each time a request is made, an Action is instantiated.? Spring MVC is more concise and development efficient spring MVC is really higher than struts2: Support JSR303, the request to process Ajax is more convenient, only need to use annotations to complete? Struts2 's OGNL expression makes page development mor
array, releasing only one object delete instead of delete[] do not speak auto_ptr objects are stored in a container. Replication and assignment of Auto_ptr objects is destructive. After the Auto_ptr object is copied (or assigned), the original Auto_ptr object does not point to the object and the new Auto_ptr object (left operand) has the underlying object.
12 If the function is tangible as throw () description of the exception: do not throw any exceptions if there is no exception description: C
Today, when dealing with a MAC address, a problem that has not been noticed before is documented.
When the string format output is needed, the Format function is automatically thought of, and the MAC address needs to be output in two-bit width 16, so I write%x directly, but I get an error output format in the actual output: • " Fffffff0 ", it should be f0 ah.
First of all to determine their own program is not wrong, and then simple analysis, as long
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