effective java 3rd

Ref:from book "Effective Java"This was designed to the help you are familiar with fundamental libs like Java.lang, Java.util. And to a lesser extent, java.util.concurrentand java.io. The book discusses other Lib from time to time, but it does not cover graphical user interface programming, Enterprise API s, or mobile devicesThis book consist of the which items, each of the conveys one rule. The items are lo

"032-longest Valid parentheses (maximum effective bracket)""leetcode-Interview algorithm classic-java Implementation" "All topics Directory Index"Original QuestionGiven A string containing just the characters ‘(‘ ‘)‘ and, find the length of the longest valid (well-formed) parenthe SES substring."(()"for, the longest valid parentheses substring "()" are, which has length = 2.Another example ")()())" is, wher

About effective Java This book, some of his own summary of thinking. The length may not follow the catalogue, because I like to read the first chapter directly. But to be sure, each chapter will have a summary. Welcome everyone to make bricks and add.1. consider replacing the constructor with a static factory method . Pros: There is a name that does not have to be created every time the object, return any s

I need to install Pydev on eclipse, which requires native Java to be java8, otherwise it will appear in eclipse does not appear in the problemSecond, the Local has installed JAVA7 and JAVA8, but the current environment variable Java_home point to Java7Third, modify Java_home point to Java8, open cmd, set path=c: And then open another Cmd,echo%path% see the current PATH, you can see that Java_home has indeed pointed to the JAVA8 directoryBut

Finalizers is Unpredictable,often Dangerous,and generally unnecessary.Their use can cause erratic Behavior,poor performance,and portability problems.Finalizers has a few valid Uses,which we ' ll cover later in this item,but as a rule of thumb,you should avoid finalizers.C + + Programmers is cautioned not to think of finalizers as Java ' s analog of C + + destructors. In C++,destructors is the normal the Reclaim the resources associated with a object,a

ObjectiveSince March last year I began to read "effective Java second Edition", of course, I read the Chinese version of the; Maybe I can not understand the ability, for the content of the book always feel difficult to understand; take the first chapter of the content " Create and destroy objects "to say, this is the most I read the chapter, presumably the reason everyone also understand, every time I can n

Fieldholder.field for the first time, causing the Fieidhalder class to be initialized. The charm of this pattern is that the GetField method is not synchronized, and only one domain access is performed, so delayed initialization actually does not add any access cost to the well.If you need to use lazy initialization for your instance domain for performance reasons, use double-check mode (double-check idiom). This mode avoids the locking overhead of accessing the domain after the domain is initi

reflected anomalies are concentrated in the running period, which is not easy for abnormal control, so it is not recommended] Use local methods with caution [platform migration is over] Careful optimization [Analysis good optimization, as far as possible in the design of good or bad to optimize, otherwise optimization may lead to unnecessary waste] Adherence to universally accepted naming conventions [easy to understand and team consensus is the norm] Abnormal Exceptio

where the call error occurs.Destroy For example, the string class has a since 1.4 contentequals (StringBuffer), plus a since 1.5 contentequals (charsequence).(The Charsequence interface is added in Java version 1.5 and acts as a public interface for classes such as stringbuffer,stringbuilder,charbuffer,string) but it does not pose a hazard, Because the behavior of the two overloaded methods in this example is exactly the same.There are some interesti

, use Run-time exception for programming error: Java provides three types of throw structures: Client exceptions, Run-time exceptions, and errors. This entry gives a general principle for these three types of scenarios that apply. 1. If you expect the caller to recover appropriately, you should use an exception for this situation, such as if someone is planning to shop online and the resulting balance is insufficient, you can throw a custom cli

client. Also easier, when designing new types, make sure they don't need this kind of conversion, which usually means making the class generic and, as time permits, generics the existing type. This can be easier for these types of new users without destroying the existing client 27th: prioritizing generic methods Writing a generic method is similar to writing a generic type, declaring a type parameter list of type parameters, between the modifier of the method and its return type, in the follow

First, the preface Start today with a one-month plan to read the classics in the Java domain by writing reading notes--effective the Java process--for future reference, while sharing it with hope that it will help others, with little nonsense. Now start the first article: Create and Destroy objects. Second, consider using static factory method instead of the co

Max_num =NewInteger (10); Public Static FinalInteger[] Max_num_a = {NewInteger (10),NewInteger (10),NewInteger (10)}; /** * @paramargs*/ Public Static voidMain (string[] args) {//TODO auto-generated Method StubInteger II =NewInteger (11); max_num_a[1] = II;//no errors, can be assignedMax_num = II;//There is an error, you cannot assign a value }} So you can use the static final method of public to get the clone of the array, set the Max_num_a to private, and not change [

complexity. Any exception that is generated should keep the object in the state before the method call. If this rule is violated, the API documentation should clearly indicate what state the object will be in. 65th: Do not ignore exceptions Methods to ignore Exceptions: surround the method with a try block and include an empty catch block // Ignore Exception Try {// call method catch (Exception e) {} If you can ignore the exception, the catch block s

;/*** Description: Service Interface*/ Public InterfaceService {}/*** Service Provider Interface * Role: responsible for creating the service instance (if there is no service provider interface, the implementation is registered according to the class name and instantiated through class reflection) * For Jdbc,connection is the service interface, Drivermanager.registerdriver is the provider registration API * Drivermanager.getconnection is the service Access API * Driver is the service provider in

as multi-step processing, he can not guarantee that the value and +1 process is atomic, so this case requires a mutex lock synchronize lock.Synchronize lock need to pay attention to a point, is to ensure that the lock range as little as possible, release the lock; in the lock Code section try not to call the external function, because the external function is not controllable, but also easy to trigger a deadlock;Use multithreaded tools in the Java in

Tips"Effective Java, third Edition" an English version has been published, the second edition of this book presumably many people have read, known as one of the four major Java books, but the second edition of 2009 published, to now nearly 8 years, but with Java 6, 7, 8, and even 9 of the release, the

the domain is initialized.private volatile fieldtype field; FieldType GetField () { FieldType result = field; if (result = = null) { //first check (no locking) synchronized (this) { result = field; if (result = = null) {//second check (with locking) field = result = Computefieldvalue ();}} } return result;}Two check the domain value, the first check is not locked, see if the domain is initialized, the second check is locked, only when the

; result = * result + linenumber; return result; } */ //if an object is not constantly changing, and the cost is relatively large, you have to consider it. Hash code is cached inside the object//with volatile modifiers, the thread will read the variable's most-modified value each time it uses the variable. Private volatile inthashcode; @Override Public inthashcode () {intresult =hashcode; if(Result = = 0) {result= 17; Result= * result +AreaCode; Result= * result +prefix;

considered directly as an object T, then int[] as a whole is treated as an argument, not as an int parameter In addition, when it comes to performance, the array allocation and initialization of each invocation of a mutable parameter may be difficult to meet performance requirements, consider the following: If a call to a method 95% has three or fewer arguments, it declares 5 overloads of the method:1 Public voidFun () {}2 Public voidFunintA1) {}3 Public voidFunintA1,intA2) {}4 Public