java self study

Java study notes 23 --- internal class local internal class can only access final local variables, study notes 23 --- A local internal class is a class defined in the method body or code block. It has been briefly introduced in note 19. Today we will discuss why local internal classes can only access local variables that are constants. Author: blog garden-Chan P

Java Study Notes-11. type identification during runtime, Study Notes-11 1. The getClasses () method of the Class Object obtains all public internal classes in the Class and internal classes inherited from the parent Class and parent interface. The getinterfaces () method returns all interfaces inherited by the class. Import javax. print. attribute. standard. prin

). Collect (Collectors.tolist ()); List1. ForEach (E->system.out.println (e));Results:4.3 When building the test set, in addition to the normal student object, add some null to the collection, and then rewrite 4.2 so that it does not appear an exception.Generic class: Generalstack (Topic 5-5)5.1 Your Submission results (Advent number)5.2 Code for Generalstack interfaceInterface Generalstack5.3 What are the benefits of generics?No restriction of element types after generics, no more coercion of

My java Study Notes (13) Reflection (part 2), study notes Whining... This evening is a bit of a thing... As a result, there was no eclipse in the lab, and the command line was used. As a result, the environment variables were not properly configured for a long time .. Now .. Ah .. 1. The key method for viewing object fields is the get method in the Field class.

JAVA Study Notes (fifty-nine)-Socket programming, Study Notes socketClient Import java. io. IOException; import java.net. datagramPacket; import java.net. datagramSocket; import java.net. inetAddress; import java.net. unknownHostException;/** Client */public class Client {public static void main (String [] args) throws

Java study notes 18 --- final keywords modify variables, methods, and classes, study notes 18 --- final The word final in English is known as "final". In fact, it also means"Unchangeable". In Java,The final keyword is "unchangeable" to better explainThat is, the final modifier is "unchangeable ". Final can modify varia

Java Study Notes-JDBC4 (19), study notes jdbc4 16Database transactions 16.1 bank deposits # Create table account (accountid varchar (18), # account balance double () # balance) # deposit table create table inaccount (accountid varchar (18 ), # account inbalance double (100) # deposit balance): Insert into inaccount (accountid, inbalance) values ('123', 500612345

their own module code and run the video.Function Module: Login module book information Management System book borrowing module book return module book query module2.7.3: The main class design and class diagram of the system (available)2.7.4: How are you going to store library information, address information, reader information, and more?The current idea is to store it in files, but the specific implementation has not yet been thought of.3: Code Cloud and PTA3.1: Code cloud codes Submission rec

Java Study Notes 20 --- adding internal classes to member Internal classes (1), Study Notes 20 --- In the previous article, note 19 briefly introduced the internal class, local internal class, and anonymous internal class of the member, and added some content to the internal class of the member. There are mainly the following six points: 1. The member's internal

Java Study Notes 21 --- supplementary description of internal classes of members (2) (corrected), Study Notes 21 --- Fixed: the original article was a bit incorrect, mainly concerning the subclass of the member's internal classes. Due to my cognitive limitations, I think that the subclass of the internal class should also be an internal class.The points of intern

Java Study Notes day05 and Study Notes day05 1. Method overload A method with the same name is allowed in the same class, as long as the parameter list of the method is different. Different parameter lists: different parameter numbers, different parameter types, and different order. Public class MethodOverLoadDemo {public static void main (String [] args) {}

= LocalDateTime.now(); DayOfWeek dayOfWeek = now.getDayOfWeek(); if(dayOfWeek!=DayOfWeek.SATURDAY dayOfWeek!=DayOfWeek.SUNDAY){ System.out.println("上班时间"); return true; } else{ System.out.println("休息时间"); return false; } }3. Code cloud codes Submission Record 4. PTA Experiment Summary A: In the ide, you can use the program code auto-generation function to generate a value method, Click source Generate Constructors from Superclass -to Create an empty parameter constructor; click Source

Java Study Notes-JDBC2 (17), study notes jdbc2 1. Review: six fixed steps of jdbc * (take query as an example) // 1. register the driver (which can be connected to the database) DriverManager. registerDriver (new Driver (); // 2. obtain the Connection con = DriverManager object connected to the database. getConnection ("jdbc: mysql: // 127.0.0.1: 3306/mydb", "roo

content to seeTry using the Get/index http/1.0 command:4 Start the Connectionwatcher, and then start a number of Internet-enabled programs (such as QQ, Telnet, browser, etc.), to see what the computer on the Internet, what port is used? What ports does QQ use to interact with those remote IPs, where are these IPs distributed? What protocols are used for communication?QQ uses 80 port, ip:183.232.103.219, Shenzhen city, Guangdong province360 browser is using 80 port, ip:180.163.251.158, Shanghai,

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Java language-Case Study of Tetris Java source code, java Tetris Only reference source code is provided Import java. awt. *; import java. applet. applet; public class Blocks extends Applet implements Runnable {Dimension d; Font la

Java Study Notes (3) data types, java Data Types Data Type: The data type determines the storage space occupied by the data in the memory and the storage method. Each data type has its value range. The Compiler allocates memory space for each variable or constant data type. Java data types can be classified into two ty

(marshaller.jaxb_encoding, "GBK"); //do you want to bring Marshaller.setproperty (marshaller.jaxb_fragment, Boolean.false); //Format the XML outputMarshaller.setproperty (Marshaller.jaxb_formatted_output, boolean.true); //convert an object to an XML in the form of an output stream Marshaller.marshal (Opdetail, SW); } Catch(jaxbexception e) {e.printstacktrace (); } System.out.println (sw.tostring ());/* Output is as follows:*//*converting an XML string into a

Crazy Java Study Notes (88) ----------- worth ten books and crazy java Handouts Java is one of the most popular programming languages nowadays. There are also a large number of books suitable for beginners on the market. But for developers who have been immersed in Java prog

Well-off study with you JAVA -------- data type conversion, java type conversion This article describes a common output situation in JAVA: data type conversion. The data type of Java has been determined at the time of definition, so it cannot be converted to other data type