word questions and answers

synchronized, they can be entered. 21. When an object is passed as a parameter to a method, this method can change the properties of the object and return the changed result, so is it a value pass or a reference pass? In Java, only the value is passed, and if the object is passed, the address of the object is actually passed. 22. Scope public,private,protected, and the difference between non-write public modifier, which means any class can be accessed. Protected is a protected modifier that rep

tee filter?Answer: The tee filter is used to send output to multiple destinations. If used for pipelines, it can copy the output to one file and copy the other to the screen (or some other program).[Email protected]:~$ ll/etc | NL | Tee/tmp/ll.outIn the example above, the LL output can be captured in the/tmp/ll.out file and also displayed on the screen.Q: Export PS1 = "[Email protected]:\ $PWD: What is this command doing?]A: This export command changes the login prompt to display the user name,

on another thread's message, and waits until the message arrives when it does not get another thread's message.Thread mutex refers to the exclusive nature of the shared process system resources when each individual thread accesses it. When there are several threads that want to use a shared resource, at most one thread is allowed to use at most, and other threads that want to use that resource must wait until the resource is freed by the resource. Thread mutexes can be seen as a special kind of

Server and so on.2. Under the premise of not destroying the 1 deployment, also use Oldboy user to complete multiple keys to a lock (B,c key, a lock)-Free landing deployment as follows:B---------->aC---------->aNote: This topic is used in the production environment, data backup, etc., but the production environment this way is recommended to be implemented by the daemon process.The goal of the final realization is, 1, 22 topics to achieve two-way password-free authentication login.3. If you incr

and executed successively. Even in multithreaded mode, all commands are atomic unless the program has a bug:)The command sequence is not atomic. If you get an item with a GET command, modify it, and then want to set it back to memcached, we don't guarantee that the item is not manipulated by another process (process, not necessarily an operating system). In the case of concurrency, you may also overwrite an item that is set by another process.Memcached 1.2.5 and later, the Get and CAS commands

? What is Futuretask? How to wake up a blocked thread? How do immutable objects help with multithreading? What does multi-threaded context switching mean? What thread scheduling algorithms are used in Java? What is the role of Thread.Sleep (0)? What is the Java memory model, which areas are thread-shared, and which are unshared What are optimistic and pessimistic locks? Why do I synchronize the size () method of the Hashtable? Synchronization methods and synchronization block

++;Parent.printvalue ();　　((child) parent). myvalue++;Parent.printvalue ();}}Operation Result:Summarize:When a subclass has the same method as the parent class, and a parent class variable refers to a subclass object, which method is called, determined by the object's own "true" type, that is, the object is a subtype, it calls the method of the subtype, it is the parent type, and it invokes the method of the parent type. This feature is actually a concrete representation of the object-oriented "

as the struts,spring MVC framework, which cleanly isolates business objects and control logic with control inversion. It also allows binding of request parameters and business objects in a declarative manner.Dispatcherservlet.The Spring MVC Framework is designed around Dispatcherservlet to handle all HTTP requests and responses.Webapplicationcontext.Webapplicationcontext inherits ApplicationContext and adds some unique features to the Web application that are different from the general Applicat

The main points of installing a dual operating system are: (1) disk planning, note that dual operating systems should be installed in different partitions, (2) for beginners, it is best to install from a low to a high version; (3) Boot.ini, Ntdetect and Mldr These three files are very important for the boot of the dual operating system, and a backup is usually available. If you want to install 3 or more systems on your computer, it's easy to do so, as long as you plan your partitions and then i

Tags: sql face question SQL exerciseStructure of the tableStudent (s#,sname,sage,ssex) Student tableCourse (c#,cname,t#) timetableSC (s#,c#,score) score tableTeacher (t#,tname) Teacher table 1. Creating the corresponding table CREATE table student (' s# ' int, sname varchar (+), Sage int, s Sex varchar) The following omit 2. Inserting data insert into student Select 1, ' Zhang San ', 18, ' Male ' union ALL select 2, ' John Doe ', 18, ' Male ' Unio n all .... 3. Check the number of all stud

Label:1. Query the sname, Ssex, and class columns of all records in the student table. Select T.sname,t.ssex,t.sclass from student t; 2, the inquiry teacher all units namely does not duplicate depart column. Select * from teacher T where t.depart= ' computer system '; 3. Query all records of student table. Select *from student T; 4. Query all records from 60 to 80 of the scores in the score table. SELECT * FROM Student t where T.sno in (select E.sno from score e where degree between and 80);

, PDB1)Extract E1 successfully registered with database at SCN 2664333.Sql> select Capture_name,capture_user,status,start_scn,purpose from Dba_capture;Capture_name capture_user STATUS START_SCN PURPOSE----------------- ------------------ -------- ---------- -------------------Ogg$cap_e1 C # #GGADMIN ENABLED 2664333 GoldenGate Capture(3) testSql> Connect Pdb1_u1/[email protected]Connected.1) DMLsql> INSERT into S1 values (+);1 row created.Sql> commit;Commit complete.2) DDLsql> Create sequence SS1

Hong Kong or somewhere), after the server C to jump directly to the appropriate server. Statistics are combined with data from three machines.7 Starting now requires that the same IP cannot be repeated, please indicate how to modify the data table accordinglyALTER TABLE ' Phpinterview '. ' Poll ' ADD unique INDEX ' ix_poll_ip ' (' IP ');8. The original data already has a lot of duplicate IP data, so we export it to a TXT, the format and the top of the poll consistent, with the TAB key interval,

itself.Prototype: The prototype range is the opposite of a singleton range, providing an instance for each bean request.Request: an instance of each network request from the client is created within the scope of the requesting bean, and after the request is completed, the bean is invalidated and reclaimed by the garbage collector.Session: Similar to the request scope, ensure that there is an instance of the bean in each session, and the bean will expire after the session expires.Global-session:

of the class, easy to handle exceptions;Development experience:The exception is the main processing of reading files, but also can be used with the method of reading files; can also be used for network connections where exceptions can include a large number of error messages for error handling.Code:Class Shortinputexception (Exception): def __init__ (self, length, atleast): exception.__init__ (self) self.length = length self.atleast = atleast while True: try:

article to learn more about the callable,future example.6. What is Futuretask?Futuretask is a fundamental implementation of the future, and we can use it with executors to handle asynchronous tasks. Usually we do not need to use the Futuretask class, it becomes very useful when we intend to rewrite some methods of the future interface and keep the original base implementation. We can just inherit from it and rewrite the methods we need. Read the Java futuretask example to learn how to use it.7.

Please give answers! Fc11 partition-general Linux technology-Linux technology and application information. For more information, see the following section. I want to know a few questions: 1. the/usr partition is used to install the software. Is it necessary to separate it into one partition? If I have installed the software after I reinstall the system, can I still use it? Is it necessary to keep this part

= "Video/ogg"> TrackKind= "Subtitles"label= "中文版"src= "T_EN.VTT"Srclang= "en"default> Track> TrackKind= "Subtitles"label= "Arabic"src= "T_AR.VTT"Srclang= "AR"> Track>Video>4. What media labels are available in addition to audio and VIDEO,HTML5?HTML5 provides strong support for multimedia, with the following tags supported in addition to audio and video tags:typesrc= "Test.mov">5. What is the use of HTML5 Canvas elements?The Canvas element is used to draw a graphic on a Web page, and th

); },10); The previous code allows the settimeout loop to trigger. However, the execution of this block of code suspends the time, so two execution times are greater than 10 milliseconds SetInterval (function () { /* code block */ },10); And the previous code, is automatically in 10 when the event hangs, so two times the interval of the event will be less than or equal to 10 milliseconds.When a thread is blocked at an event, either using SetInterval or settimeout waits f

business objects and control logic with control inversion. It also allows binding of request parameters and business objects in a declarative manner. DispatcherservletThe Spring MVC Framework is designed around Dispatcherservlet to handle all HTTP requests and responses. WebapplicationcontextWebapplicationcontext inherits ApplicationContext and adds some unique features to the Web application that are different from the general ApplicationContext because it handles the subject and finds the