core java programming questions

);　　Result.setsecond (Maxmanager); Manager m=(Manager) Result.getfirst (); System.out.println (M.getbonus ()); }　　8.3 SummaryIn general: Wildcard characters with a super-type qualification can be written to a generic object, and wildcard characters with sub-type qualification can be read from generic objects.　8.4 Schedule (Manager Class) Packagecom.ebao.gs.pol.nb.test; Public classManager {PrivateLong ID; PrivateString name; PrivateDouble Bonus; PublicManager (Long ID, String name, Doubl

Java an overview of the core technology programmingI. Features of the Java languageSimple line: Learn from C + +, excluding the C + + infrequently used pointers, structures, etc., to increase garbage collection.Object-oriented: different from C + + is single inheritance, but can inherit multiple interfaces. Fully object-oriented language;Network skills: Socket,ft

. String---> Byte streamCombines the functions of both bufferedwriter/outputstreamwriter2. can automatically refreshNew PrintWriter (os,true);UDP User Data Message Protocol-------------------------------------------1) Consider the efficiency of data transmission, reliability is not guaranteed2) Not necessarily a one-to-many communication, such as broadcasting3) non-connected, unreliable transmission modeDatagramsocket responsible for sending and receiving data such as the PostmanDatagrampacket d

Java core programming-file filtering class (FileFilter and FilenameFilter ), 1. FileFilter Package test; import java. io. file; import java. io. fileFilter; public class FileFilterTest implements FileFilter {private String extension; public FileFilterTest (String extension)

Java core programming-byte stream of IO stream (2), javaio 1. byte stream A 1.1-byte stream is a stream that operates byte. Byte streams can operate on any data, such as media data, music, movies, and images. Of course, they can also operate on characters. Byte stream is based on byte stream, we know that a byte is 8 binary bits, a byte corresponds to an English

routine to review the concepts that we have described earlierPackage pair3; Public classpairtest3{ Public Static void Main(string[] args) {Manager CEO =NewManager ("Gus greedy.",800000,2003, A, the); Manager CFO =NewManager ("Sid Sneaky",600000,2003, A, the); PairNewPair1000000); Cfo.setbonus (500000); Manager[] Managers = {CEO, CFO}; pairNewPair out. println ("First:"+ Result.getfirst (). GetName () +", Second:"+ Result.getsecond (). GetName ()); Maxminbonus (managers, result); Syste

The basic course of Java language programming Practice Study Questions Reference answers 1th Chapter Java Programming Overview 1.9 Practice Study Questions 1, the Java running pl

Java core programming-File operations, javafile 1. Overview Access to the File system is required for each language. java provides the File class to create, rename, delete, operate on the File list, and determine whether the File or directory exists. 2. Operations on files/Directories The operations include: 1: Create

A termJdk:java delelpment JitJre:java Runtime EnvironmentSecond, installation jdk1.8.0_25Setting environment variables (recommended to be installed directly under C-drive), using;C: \java\jre1.8.0_25\bin;Third, unzip the source file methodEnter C: \java\jre1.8.0_25Create SRC subdirectorymkdir SRCCdsrcUnzip the fileJar XVF. \src.zipI. Using command-line toolsJava Helloworld.java with

-generated Catch blockE.printstacktrace (); } }}4. Use Ruturn to stop the thread Public classMyThreadextendsThread {@Override Public voidrun () { while(true) { if( This. isinterrupted ()) {System.out.println ("Stop it!"); return; } System.out.println ("Timer=" +System.currenttimemillis ()); } } Public Static voidMain (string[] args)throwsinterruptedexception {MyThread T=NewMyThread (); T.start (); Thread.Sleep (2000); T.interrupt (); }}Results:Two(1) Advantages

Java core programming-IO stream Overview (-), javaio 1. Four most critical parent classes of java io streams ~ InputStream (input byte stream) ~ OutputStream (output byte stream) ~ Reader (input stream) ~ Writer (output streams) All the above four classes are public abstract class classes. InputStream and Output

=NewOutputStreamWriter (FileOutputStream); //building character output stream objectsBufferedWriter BufferedWriter =NewBufferedWriter (OutputStreamWriter); //Building Data Char[] chars =New Char[3]; chars[0] = ' a '; chars[1] = ' B '; chars[2] = ' Medium '; //Output DataBufferedwriter.write (chars); //Close the streamBufferedwriter.close (); Outputstreamwriter.close (); Fileoutputstream.close (); } Catch(FileNotFoundException e) {e.printstacktrace (); } Catch(IOExce

A basic data structureMust be included in the classMust have public static Main methodCase sensitiveIi. Types of dataFour types of integers:INT 4 byte short 2 byte Long8 byte byte1 byteTwo floating-point typesFloat 4 bytesDouleble 8 bytesChar Type, Boolean typeConstants use the final definition class constants using the static final definitionThird, Operation symbolsX!=0 1/x>x+y//If x=0, do not perform the calculation behind avoid x=0 1/x operationMathematical operation symbol MATH.PI, etc.Iv.

50 Classic Java Programming questions (directory)Title from: http://blog.sina.com.cn/s/blog_60fafdda0100wb21.html "Program 1" Testrabbit.javaTitle: Classical Questions: There are a pair of rabbits, from the 3rd month after birth a pair of rabbits each month, the rabbit long to the third month after the birth o

As a business developer, there are few technologies that can be used at work. Although usually always say what, multi-threading, concurrency, injection, Attack! But in practical work, these things are not necessarily used. Because the framework we used has already done that.For example, web development, there are a lot of requests coming in, supposedly, we should consider concurrency problems. But in fact, Spring receives the request, after assigning to the controller, it is already thread-safe,

byte[] B =New byte[3];//reading byte numbers, creating arraysRandomaccess.read (b, 1, 2);//read two bytes from pointer 1 write to array bString s =NewString (b);//Convert to StringSystem.out.println ("byte:" +s);//Output//Write FileFile file2 =NewFile ("C:\\img\\777.txt"); if(!File2.getparentfile (). exists ()) {File2.getparentfile (). Mkdirs (); } file2.createnewfile (); Randomaccessfile RandomAccess2=NewRandomaccessfile (File2, "RWD");//Accessi

Feedback on issues with the 2017 object-oriented Programming (JAVA) section on nine-week learning summary1. Blog not written by: Gao Shuping Gao Junmei Fong Mau Wang Ruiqiang Zong Peng Li Xianglong Ma Lun Mitch Mao Provencale--The number of students who do not submit the blog in time is on the rise, please think about the value of Java Learning Blog, and some of

The book is generally finished, but the seventh chapter is not in a hurry to end.But fortunately it is finished, barely count it.Recall this year, quite feeling, the heart has been seeking progress, but it is very difficult to act up.Think about it indeed ah, want to always progress must sacrifice their spare time, although not to exclude learning, but you have to admit that the feeling of paralysis is very good.Man, there's really nothing to stop, and once you get down, you're probably going to

: Use node stream as input or output. The filter stream is created using an existing input stream or an output stream connection.6. Java SOCKET Programming, read the server several characters, and then write to the local display. After the client sends a connection request to the server, it passively waits for the server to respond.A typical TCP client is going through the following three steps:1. Create a

letter I in the string; intn =0; for(intA =0; A if(' I '= = Str[a]) {n++; }} System. out. println ("(2) The number of occurrences of the letter I in the string:"+ N); System. out. println ("\ n");//(3) Remove substring "my";System. out. println ("(3) Remove substring" my "); System. out. println (S1.substring (S1.indexof ("My"), S1.indexof ("My") +"My". Length ())); System. out. println ("\ n");//(4) converts this string into an array of strings, requiring each array eleme