java certification test questions

are awakened, it releases the lock, and the sleep () method simply frees the CPU resources or causes the current thread to stop executing for a period of time, but does not release the lock. You can check this article for more information.These are the 50 popular Java multithreading and concurrency test questions. I did not share the answers to all the

"Declaration" Source: Power node Java Institute, reprint Source: Script House (The answer to a small number of questions was slightly altered by me) 1, what is the thread local variable. A thread-local variable is a variable within the thread itself, owned by the thread itself, and not shared among multiple threads. Java provides a ThreadLocal class to support t

this and put??? Well, it would call accumulate??? System.out.println ("object:" + object.tostring ()); }}Console Print Results:jsonObject: {"one":"first"}jsonObject: {"one":"first","two":"second"}jsonObject: {"one":"first","two":"cover"}jsonObject: {"two":"cover"}jsonObj: {"Servers":[null,"Tomcat"],"Codes":["Java","JavaScript"]}object: {"price":"1000"}Questions: net.sf.json.element :Put

(BookName) is the "Java" record, the following code is correct (aString sql= "Delete from book where bookname=?";PreparedStatement pst=con.preparedstatement (SQL);______________________________Pst.execute ();A) pst.setstring (1, "Java");B) pst.setstring (0, "Java");C) pst.setint (0, "Java");D) The above options are no

causes the current thread to stop executing for a period of time, but does not release the lock. You can check this article for more information.These are the 50 popular Java multithreading and concurrency test questions. I did not share the answers to all the questions but provided enough hints and clues for future r

class hello{public static void Main (string[] ARS) {A ab = new B (); Executed here, results: 1a2bAB = new B (); Executed here, results: 1a2b2b}}A: the output is 1a2b2b; the static code snippet for a class can be thought of as code executed by the class for the first load (virtual machine load), and for class loading, the first thing to do is to execute the construction of its base class, and then perform its own construction.50, the Succession time class execution order question, generally is t

. Provides a variety of distributed transaction services. The application simply invokes the interface it provides.(4) Jaf:java Action Framework,java Security Certification framework. Provides a framework for security controls. Let developers implement their own personalized security control strategies through various deployments and customizations.(5) Rmi:remote methods Interface, remote method call 　　What

variable, the value of the variable in the object changes.[Java]View PlainCopy "FONT-SIZE:14PX;" >public class Demo { //class variable (static variable) public static int a = 0; //Instance variable private String namestring; } Third, local variablesA parameter in a method or a local block that declares a defined variable or method is called a local variable, and they exist only in the block where they were creat

More Java interview written paper series:Java interview written test stationHow does the 1.Java hashmap work?HashMap is a key value for the data structure, each key will have a corresponding value, the key is to identify such a value.HashMap based on the hashing principle, we store and retrieve objects through the put () and get () methods. When we pass a key-val

The following is a Java certificate: HTTPS and SSL application notes test. I hope this article will help you. When a connection is obtained, like a normal browser, the server certificate is still verified to be trusted (issued by an authority or signed by an authority). If the server certificate is untrusted, the default implementation will be problematic. Generally, errors are often reported when

implementation of future, and we can use it with executors to handle asynchronous tasks. Usually we do not need to use the Futuretask class, and it becomes very useful when we intend to rewrite some of the methods of the future interface and maintain the original base implementation. We can just inherit from it and rewrite the methods we need. 7. What is the implementation of concurrent containers?Java collection classes are fast failures, which mea

Java interview questions Basic knowledge:1. simple principles and applications of the Exception Handling Mechanism in C ++ or Java. When a Java program violates the Java Semantic Rules, the Java Virtual Machine will indicate an er

between 4.forward and redirect Forward:an internal transfer in servletRedirect: Redirect, 2 times request, 2nd request will lose the first attributs/parameters and so on5. What is a Web container? Realize the application of Web protocol in Java EE specification. This protocol defines the runtime environment for Web applications, including concurrency, security, lifecycle management, and so on.6. Explain the following nouns about

First, let's talk about the differences between final, finally, and finalize.　　Second, can anonymous inner class (anonymous internal class) be extends (inherited) other classes, or implements (implemented) interface (Interface )?　　Third, the difference between static nested class and inner class is that the more you say, the better (the more general the interview questions are ).　　Fourth, the difference between and.　　Fifth, the difference between has

Some questions that are frequently asked during interviews with Java programmers on the Internet, although a little old, are still worth reading. 1. Let's talk about the differences between final, finally, and finalize. Final? Modifier (keyword) If a class is declared as final, it means that it cannot generate a new subclass and cannot be inherited as a parent class. Therefore, a class cannot be declared bo

The Spring framework is now almost a standard framework for Java WEB development. So, as a Java programmer, how much do you know about Spring's main technical points? You may want to use the questions in this article to check.1. General questions1.1. What are the main features of different versions of the Spring Framework?Versionfeaturespring 2.5 was released in

Jame Dean 2016-12-06 17:12 Basic Knowledge section (90 points) one, the single choice question (altogether 12 questions, each question 3 points, altogether 36 points. ) 1, Java is from (B) language improvement redesign. A) Ada B) C + + C) pasacal D) BASIC 2. Which of the following statements is correct (B) A Java program generates machine code after compiling B

);2, Student s first in the stack memory to open up the stack memory space, create a student object, the heap memory needs to request heap memory space;3, through the non-parametric construction method to the Student class object default initialization;4, by assigning values to the member variables, the object is displayed to initialize;5, the display initialization is complete, after the whole object is created, the object is allocated the memory space address value;6, find the corresponding ob

Collector deletes an object. 13. Can anonymous inner class (anonymous internal class) be extends (inherited) other classes, or implements (implemented) interface (Interface )? An anonymous internal class is an internal class without a name. It cannot be extends (inherited) other classes, but an internal class can be used as an interface and implemented by another internal class. 14. The difference between static nested class and inner class is that the more you say, the better (the more general

Basic java exception knowledge and some interview questions Java is an object-oriented design language, so exceptions are encapsulated into classes in java, and we only need to know how to handle exceptions, Exception Overview Exception: An exception occurs when the Java pro