udemy java course review

ObjectiveReviewing the Java modifiers and the string class in the previous article, this article looks back at the three main features of Java: Encapsulation, inheritance, polymorphism.Encapsulate what is encapsulated In the object-oriented programming approach, encapsulation refers to a method of wrapping and hiding the implementation details of an abstract function interface. Encapsulation ca

Weekly Job Link Summary Preview Homework One: http://www.cnblogs.com/taigenzhenjun/p/6492903.html to professional expectations Preview Homework Two: http://www.cnblogs.com/taigenzhenjun/p/6195785.html a review of C language learning Preview Job Three: http://www.cnblogs.com/taigenzhenjun/p/6308577.html Linux virtual machine installation and learning of Linux commands First week: http://www.cnblogs.com/taigenzhenjun/p/6446296.html

, 2) or change the three-mesh operator operand to an object.Integer Leftnum = (null! = Leftnummap !leftnummap.isempty ())? Leftnummap.get (Stat.getdepartmentid ()): integer.valueof (0);3 mapThe following data structures are often present in our code, such as the key is the category, and value is a list,list that stores the statistical data for each subclass of the class.mapThis is often the case when we insert this data structure:void Putmyobject (String key, Object value) { listWhen we want

is worse than the ArrayList, LinkedList using the two-way linked list to implement storage, indexed by ordinal data needs to be traversed forward or backward, but when inserting data only need to record the item's front and rear items, So insert several faster!ArrayList and LinkedList1.ArrayList is the realization of the data structure based on dynamic array, LinkedList data structure based on linked list.2. For random access get and set,arraylist feel better than LinkedList, because linkedlist

Java web crawler Technology, the discovery of web crawler technology first divided into the following steps:1. Open Web Link2, the page code with a BufferedReader storageHere is a code example that I made:In the process of learning web crawler first to import two packages: Htmllexer.jar,htmlparser.jarpublic static void Main (string[] args) { try { URL url = new URL ("http://www.baidu.com"); httpurlconnection Httpurl = (httpurlconnection) url.opencon

Analysis Demand analysis (including learning new technologies) 300 360 Coding Standard Code specification (to develop appropriate specifications for current development) 30 15 Design UML Design Project UML class diagram 60 120 Coding Specific code 2000 2400 Code Review Code

Standard Code specification (to develop appropriate specifications for current development) 60 Design UML Design Project UML class diagram 60 Coding Specific code 1500 Code Review Code review 30 Test tests (Self-test, modify code, commit changes) 300 Size Measurement calculation effort (a

Course Summary Lessons learned and deficienciesJava is a simple, object-oriented, distributed, interpretive, robust, secure, structured-neutral, portable, dynamic language with excellent performance and multithreading. Java is used as the development language for Java-based object-oriented and portability. Your own harvest.Learn

the code is tired of the relay. The downside might be that you're not demanding enough when you write your code, and sometimes there are some typos. On the whole, with Steven Uptown children's shoes knot pair learning is very happy, hope in the next pair of programming projects to build up and progress together!!PSP Time Statistics PSP2.1 Personal software Process Stages Estimated time-consuming (minutes) actual time elapsed (minutes)

Development Development 800 Analysis Demand analysis (including learning new technologies) 100 Coding Standard Code specification (to develop appropriate specifications for current development) 30 Design UML Design Project UML class diagram 50 Coding Specific code 30 Code

1. Sleep ()causes the current thread (that is, the thread that called the method) to pause for a period of time so that other threads can continue to execute, but it does not release the object lock (if it is in a synchronized block, He's not going to release the lock. ). This means that if there is a synchronized synchronization block, other threads still cannot access the shared data. Note that the method is a static method, but the system automatically recognizes which thread called the sleep

an abstract class and an interface?(1) Abstract classes need to be inherited, and can only be inherited. Interface needs to be implemented, and can be implemented more, that is, to implement multiple interfaces(2) Abstract classes can be defined abstract methods and non-abstract methods, subclass inheritance can directly invoke non-abstract methods, the interface can only define abstract methods (that is, all of the interfaces are not implemented methods), subclasses must implement their method

overridden by subclasses.3. As long as an abstract class containing an abstract method, the method must be defined as an abstract class, whether or not there are other methods included.4, the abstract class can contain specific methods, of course, can not contain abstract methods.5. Abstract methods in subclasses cannot have the same name as the abstract methods of the parent class.6. Abstract cannot be modified in the same class as final. (Abstract

the next state), but there is still a possibility of a "live lock". If five philosophers enter the restaurant at exactly the same time and pick up the chopsticks at the same time, then the philosophers will wait five minutes while putting down their chopsticks, waiting for five minutes, and picking up the chopsticks at the same time. 10. Thread Group Thread groups: All threads are part of a thread group, which can be a default thread group, or a group that is explicitly specified when a threa

name is entered, then the DNS is resolved and then sent over the network to the server address The server accepts the request and resolves and packages the request information into the Httpservletrequest/response object web.xmllook for the specified url-pattern , according to Servlet-name find Servlet-class The container detects if there is an object in memory for that servlet, if any, uses the original object, and if not, constructs the Servlet object using reflection The "Obje

-consuming (minutes) Planning Plan 60 Estimate Estimate how long this task will take 3 Development Development 2000 3000 Analysis Demand analysis (including learning new technologies) 350 Coding Standard Code specification (to develop appropriate specifications for current development) 60 Design UML Design Project UML class diagram 60

Estimate Estimate how long this task will take 100 100 Development Development 800 Analysis Demand analysis (including learning new technologies) 100 Coding Standard Code specification (to develop appropriate specifications for current development) 30 Design UML Design Project UML class diagram 50 C

isDescribes the exceptions that the program catches, such as classnotfoundexception. The error class is used to indicate a reasonable application but becauseJVM errors, such as virtual machine error virtualmachineerror. (the error does not allow the programmer to capture)Custom exceptions can inherit the Throwable class or exception, and do not inherit the error class. And there can be inheritance between custom exceptions.Public to design a work function for a custom exception, construct a cus

patterns, the data Accessor mode and the Active domain object (domain objects) pattern . The data Accessor mode enables the separation of access and business logic, and the Active Domain object mode enables the object encapsulation of business data.Two. The formation of DAO patternsA typical DAO implementation has the following components: A DAO interface; A concrete class to implement DAO interface; Data passing Object (DTO): Sometimes called value object (VO) or domain model