java code snippets for practice

=NewScanner (system.in); intn =In.nextint (); intm =In.nextint (); VectorNewVector(); for(inti = 0;i ) List.add (In.nextint ()); for(inti = 0;i ) {String operation=In.next (); if(Operation.equals ("ADD")) { intP =In.nextint (); intQ =In.nextint (); intj =List.indexof (P); List.add (J, Q); } Else if(Operation.equals ("DEL")) { intP =In.nextint (); intj =List.indexof (P); List.remove (j); }} System.out.println (List.size ()); for

A large number of images may exist in a website. Some images are the same for all webpages, such as the logo of a webpage and images on the home page. These images are like common HTML files, the processing of these images is usually done by the Web editing tool, that is, it is usually done by the artist. The following HTML Tag is used: SRC specifies the file path and uses the relative path, generally, we create a folder named images in the Web application to store all the images. Generally, th

Java serialization and deserialization (practice)Basic concepts:Serialization is the process of converting an object's state into a format that can be persisted or transmitted. Relative to serialization is deserialization, which transforms a stream into an object. Together, these two processes make it easy to store and transfer data.I saw it in a book yesterday, practiced it, serialized it as a generic file

priority-ordered blocking queue that can sort all placed elements (implementing the Comparator interface)29, when a method, can throw interruptedexception, means that this method is a blocking method, if it is interrupted, will prematurely end the blocking state.When you call a blocking method, it also means that itself is called a blocking method because you have to wait for the blocking method to return.If the blocking method throws an interrupt exception, what we need to do is to throw it to

is compared, if the same, it means that there has not been a write operation, the result of the original traversal is returned, if not the same, the process is repeated again, if not the same, It is necessary to lock all the segment and then one through. Public intsize () {//Try a few times to get accurate count. On failure due to//continuous async changes in table, resort to locking. FinalSegment This. Segments; intsize; BooleanOverflow//true if size overflows LongSum//Sum of mo

, the minimum value of the vector in the corresponding query interval. Sample Input7 41-1-4 8 1 2-70 01 34 50 6Sample Output1-41-7Sample DescriptionThe first query [0,0] means min{a[0]}=min{1}=1The second query [1,3] means min{a[1],a[2],a[3]}=min{-1,-4,8}=-4The third query [4,5] means min{a[4],a[5]}=min{1,2}=1the fourth query [0,6] means querying the entire vector, seeking min{a[0..6]}=min{1,-1,-4,8,1,2,-7}=-7data size and conventions12 Solutions The specific

the 3-digit number is in num case Public voidPrintresult (intKintL) { for(inti = 0;i ) dp[1][i] = 1;//target number lowest bitInitialize to 0~k-1 in turn, with each number appearing only once for(inti = 2;i //the position of the number, the highest bit is L, the lowest bit is 1 for(intj = 0;j ) { for(intF = 0;f ) { if(F-1! = J F + 1! =j) {Dp[i][j]+ = Dp[i-1][f]; DP[I][J]%=MoD; } } } } intsu

2. Thread security 2.1 What is thread-safeWhen multiple threads are accessed, the program can be " correct ", which is thread-safe.An object that has no status (a class that can be understood as having no fields) must be thread safe.2.2 atomicityIn a typical case, the i++ in a multithreaded state is not secure. Because i++ is actually implemented in a number of steps, the execution of multiple threads can be confusing to each other.Race condition (Race Conditions)Threads and threads need to depe

Whether in netbeans or in eclipse development environment, write JavaCodeThe @ override label is often encountered. Usually, you only need to know the meaning of overwriting ~ Is the value of this tag only available? The last time I reviewed thinking in Java, I read it myself. As a result, this small tag actually deepens my understanding of object-oriented. General Purpose Helps you check whether the methods in the parent class are correct.

volatile, you cannot use volatile to safely implement counters--you must use locks. However, you can use volatile in a read operation to ensure the visibility of the current value, so you can use the lock to make all the changes, using volatile for read-only operations. Where the lock allows only one thread to access the value at a time, volatile allows multiple threads to perform read operations, so when using the volatile guarantee to read the code

strictly follow the use of volatile conditions-that is, the variable is really independent of the other variables and its own previous values-in some cases you can use the volatile substitution synchronized to simplify the code. However, volatile the code used is often more error-prone than code that uses locks. The pattern described in this article covers some

always holds the correct lock when visiting the data.A closed mechanism is easier to construct a thread-safe class, because when the state of the enclosing class is parsed, the entire program is not required to examine the thread security of the class.Even if the closure can guarantee that all processing within the object is readily available, it is also important to note that when the object is advertised, it is possible to fail, such as hashset-only one variable in the sample object ensures t

"). ReplaceAll ("W", "X"). ReplaceAll ("x", "Y"). ReplaceAll ("Y", "Z"). ReplaceAll ("Z", "A")) ; 3. Randomly generate 4-bit verification code, the user input and verify that the input is correct, if the input error to generate a new verification code to allow users to re-enter, up to 5 timesString str= "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";Char[]arr=new char[4];//defines an

the method that specifies the file that the Formtemplateid points to3 */4 PublicString Downloadformtemplatebyid ()throwsexception{5HttpServletRequest request=servletactioncontext.getrequest ();6HttpServletResponse response=servletactioncontext.getresponse ();7String formtemplateid=request.getparameter ("Formtemplateid");8Formtemplate formtemplate=Formtemplateservice.getformtemplatebyid (Formtemplateid);9File file=NewFile (Formtemplate.geturl ());TenString Filename=urlencoder.encode (F

Java Theory and Practice: Correct Use of Volatile variables (1) The volatile variable in Java can be seen as a "to a lesser extent"synchronized"; AndsynchronizedCompared with the block, the volatile variable requires less encoding and less runtime overhead. However, the only function it can implement issynchronized. This article introduces several effective mod

return 0; the}G. Flood problemsTime limit: C/s 1 sec, other languages 2 secondsSpace limitations: C/C + + 32768K, other languages 65536K64bit IO Format:%lldLinks: Https://www.nowcoder.com/acm/contest/75/GSource: Cow Network topic Description Give a number n, ask 1 to N, how many number is not a multiple of 2 5 11 13. Input Description:There are multiple sets of inputsOne number per line n,1Output Description:The output output of each row is not a multiple of 2 5 11 13.Example 1 input15Outpu

#Sentinel nodeHttps://en.wikipedia.org/wiki/Sentinel_node#First_version_using_NULL_as_an_end-of-list_indicator# Reference Code, note import two librariesReference: http://blog.csdn.net/u010005281/article/details/50812328/****************************************************************************** * Compilation:javac Linkedstack.java * Execution:java Linkedstack Https://algs4.cs.princeton.edu/13stacks/tobe.txt* * A generic stack, implemented using

);Wuyi } the } - Private Static voidCopyFile (file srcfile, file newFile)throwsIOException { WuBufferedinputstream bis =NewBufferedinputstream (NewFileInputStream ( - srcfile)); AboutBufferedoutputstream BOS =NewBufferedoutputstream ( $ NewFileOutputStream (NewFile)); - byte[] Bys =New byte[1024]; - intLen = 0; - while(len = Bis.read (bys))! =-1) { ABos.write (bys, 0, Len); + } the bos.close (); - bis.close (); $ } the}

Recently Java opened an object-oriented curriculum, the teacher assigned the homework, ah, that is, what homework I don't how to describe, code as follows, do their own, code is very immature, please understand! That's about it:classstudent{PrivateString Stuno; PrivateString name; Private floatMath; Private float中文版; Private floatcomputer; /*Student () {}*/ P