core java programming questions

JAVA concurrencyParallel programming in Java is complicated, and I don't understand it deeply. But recently, due to the parallel training of classifiers, pondering a little, there are errors please correct me. Just a rough introduction.Many problems we use sequential programming can be solved, but some problems if you

1.1Java Programming PlatformJava is not just a language, but also a complete platform, with a huge library of reusable code and an execution environment that provides services such as security, portability across operating systems, and automated garbage collection. Java has both a pleasing semantics and a large library to help us implement some of the functions (in fact, code reuse)One of the advantages o

In a typical Java interview, the interviewer asks the basic concepts of the thread, such as: why you need to use threads, how to create threads, and how to create threads better (for example, inheriting the thread class or calling the Runnable interface), And then gradually asked what concurrency problems were like in Java concurrency programming,

class does not have a way to modify the strings, if you really want to change them The following expressions are legal The = = operator detects whether two strings are placed in the same position In fact, only string constants are shared, and the results of operations such as + or substring are not shared Issupplementarycodepoint (int codepoint) is a Boolean method of the character class that determines whether the specified character (Unicode code point) i

machine stack describes the memory model that is executed by the Java method: When each method is executed, a stack frame (stackframe) is created to store the local variable table, the operand stack, the dynamic link, the method exit, and so on.Heap:: Storing object instancesDirect Memory: NIO use2.java class Loading processThe Java Virtual machine loads the dat

Java is designed for consumer smart electronics, but smart home appliances are not as big as they were originally imagined. However, in the 90 's, the Internet has entered an explosive stage of development, and overnight, everyone is busy connecting their computers to the network. This time, met a big problem. People find that the Internet is connected to a variety of computers, such as IBM PCs, Macs, various servers and so on, not only the hardware C

　 The Java Collection Framework is the most frequently asked question of Java interviewing, and it is necessary to understand the powerful features of Java technology to master the set framework. Here are some practical questions, often asked in the core

The system has organized a bit of questions about Java, including Basic, Javaweb, frame, database, multi-threaded, concurrent articles, algorithms and so on, updated in succession. Other aspects such as the front end and so on the face of the questions are also in the collation, there will be.Note: At the end of the article there are benefits! PDF version can be

;. java.util Package: Java Utility Class Library Java.util package. In this package, Java provides some useful methods and data structures. For example, Java provides a date (Data) class, a calendar class to produce and get dates and times, a random number class that produces random numbers of various types, and a stack (stack), vector, bit set (Bitset), and a ha

Java Basics Pen QuestionsWritten test purpose : Exercise everyone's written ability, will not let you in the written test in the case of the forgotten words appear. At the same time, it is also a test of their own learning results, mastering the core of the most elite knowledge points. Question: What is object-oriented? (10 points) This topic: Detection of object-oriented concepts, object-orie

Java Multithreading Core technology comb (with source code) Java Multithreading Core Technology comb the source code written in front Java multithreaded objects and variables concurrent access between threads communication lock usage Timer single case mode and multithreadi

Objectiveabout winning in the interview of the Java series of basic collection and finishing, all the topics are carefully selected, very basic and test candidates for the basic skills, should say that the chances of being interviewed is very large. Here sorting out for everyone to take a look before the interview, all the topics collated from the network, there are some errors and clerical error, thanks to the reader's enthusiastic correction, in the

0000 = 0000 0001 = 1 = 1Sum up:The range of decimal integers that can be represented by 1 bytes is:-128 ~ 127, which is -2^7 ~ 2^7-1. Programming questions (10 points per question, 50 points total) Use the If-else IF-ELSE branch structure to determine the level of the user's input and print out the score. [90 ~ 100] Print Class A[80 ~ 89] Print Class B[70 ~ 79] Print level C[60

dispatch and dispatch, and a smaller unit that can run independently than a process. Thread's StrokeThe sub-scale is less than the process, which makes the multi-threaded procedure highly concurrency, and the process typically has independent memory units at execution time, while the threads can share memory. Programming with multithreading often leads to better performance and user experience,But multithreaded programs are unfriendly to other progra

1) Now there are T1, T2, T3 three threads, how do you ensure that the T2 after the T1 execution, T3 after the implementation of T2 execution?This thread problem is usually asked during the first or phone interview phase to detect whether you are familiar with the join method. This multithreading problem is relatively simple and can be implemented using the Join method.2) What are the advantages of the lock interface in Java than the synchronized block

development tools, such as Java, Javac (Java compiler)DB directory: Java-developed database Apache Derby, is an open source 100%java developed relational database, with not much.Include directory: the C language header file supports native code programming with the

"Java Core technology"Spent half a day and read carefully the Java core technology in the class part, feel the recent programming time a lot of vaguely, "This is not right, try." What's wrong? "The confusion of this sort has been defined earlier. Main function must

the implementation of the interface class to realize the replacement system.Definition of the interface:1. The naming conventions and classes of the interfaces are the same.Example: public interface interface Name {}2. Constants can be defined in the interface, and variables cannot be defined. The properties in the interface are automatically modified with public static final. The constants in the interface must specify the initial values when they are defined.3. The methods involved in the int

is not atomic. The atomic method provided by the Atomicinteger class allows this operation to be atomic, such as the Getandincrement () method, which atomically increments the current value by one, and other data types and reference variables can be similarly manipulated.12. What happens if a thread inside a synchronization block throws an exception?This problem is a lot of Java programmers, if you can think of whether the lock release this clue to a

1. PrefaceRecently, I've seen several interesting questions about the Java Core class string. The string class is how to implement its immutable attributes, and the benefits of being designed to be immutable. Why is it not recommended to use the + sign to form a new string, it is recommended to use StringBuilder or StringBuffer. Flip through som