proveit java test questions and answers

need. Read the Java futuretask example to learn how to use it.7. What is the implementation of concurrent containers?Java collection classes are fast failures, which means that when a collection is changed and a thread iterates through the collection using Iterators, the next () method of the iterator throws a Concurrentmodificationexception exception.Concurrent containers support concurrent traversal and

, the next () method of the iterator throws a Concurrentmodificationexception exception.Concurrent containers support concurrent traversal and concurrent updates.The main classes are Concurrenthashmap, copyonwritearraylist and Copyonwritearrayset, read this article to understand How to avoid concurrentmodificationexception.8. What is the Executors class?Executors provides some tool methods for the Executor,executorservice,scheduledexecutorservice,threadfactory and callable classes.Executors can

keep the original base implementation. We can just inherit from it and rewrite the methods we need. Read the Java futuretask example to learn how to use it.7. What is the implementation of concurrent containers?Java collection classes are fast failures, which means that when a collection is changed and a thread iterates through the collection using Iterators, the next () method of the iterator throws a Con

solves this problem for us. After the online pool submits the callable task, a future object is returned, using which we can know the status of the callable task and get the result of the execution callable returned. The future provides a get () method so that we can wait for callable to end and get its execution results.Read this article to learn more about the callable,future example. 6. What is Futuretask?Futuretask is a fundamental implementation of the future, and we can use it with execut

In this article we will discuss various types of face questions in a Java interview that will allow employers to test the candidate's Java and common object-oriented programming capabilities. The following chapters are divided into two, the first one will discuss object-oriented programming and its features, about

class redefined the same method in the parent class. The Override method must have a method name, a parameter list, and a return type that are identical. The Override method does not restrict access to the original method.does 6.Java support multiple inheritance? Java does not support multiple inheritance, and each class allows only one class to be inherited, but multiple interfaces can be implemented.7. W

article to learn more about the callable,future example.6. What is Futuretask?Futuretask is a fundamental implementation of the future, and we can use it with executors to handle asynchronous tasks. Usually we do not need to use the Futuretask class, it becomes very useful when we intend to rewrite some methods of the future interface and keep the original base implementation. We can just inherit from it and rewrite the methods we need. Read the Java

choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily change the implementation later.(4) Always use type-safe gener

type as needed. For example, if you specify a size, we will choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily ch

) Select the correct collection type as needed. For example, if you specify a size, we will choose an array instead of a ArrayList. If we want to traverse a map in order of insertion, we need to use TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based prog

TreeMap. If we don't want to repeat, we should use set.(2) Some collection classes allow you to specify the initial capacity, so if we can estimate the number of stored elements, we could use it to avoid re-hashing or resizing.(3) programming based on interfaces, rather than implementation-based programming, allows us to easily change the implementation later.(4) Always use type-safe generics to avoid classcastexception at run time.(5) Using the immutable classes provided by the JDK as key to t

corresponding action, while the user's data to fill the corresponding actionform, and then the Actionform is distributed to action for processing.3.Action automatically calls the Excute method, in which the action takes the user-filled data from the Actionform and invokes the model (JavaBean) for processing, and then displays the results of the processing in a different view (JSP page)struts-config.xml:struts 's configuration file .It says that each user's request is handled and forwarded throu

after the real object is called.Proxy mode,The proxy class and the proxy class implement the same interfaceAn instance of a proxy class in a proxy classBehavioral patterns: Focus on communication between objectsSuch as: Responsibility chain mode, iterator mode, command modeResponsibility chain ModelSimilar interceptors, etc.Command mode:Separates callers from Callee's behaviorInterpreter mode:Each syntax is an interpreter classIterator mode:Change the collection class's view traversal and add a

most cases, we only need to determine if the values are equal, and then compare them with the Equals method.There is also a equalsignorecase that can be used to ignore case comparisons. String s1 = "abc"; String s2 = "abc"; String s3= new String("abc"); System.out.println("s1 == s2 ? "+(s1==s2)); //true System.out.println("s1 == s3 ? "+(s1==s3)); //false System.out.println("s1 equals s3 ? "+(s1.equals(s3))); //true12. What is a string pool?As the name i

equalsignorecase that can be used to ignore case comparisons."ABC"; "abc"; String ("abc"); System.out.println (//true System.out.println (//false System.out.println (//true 12. What is a string pool?As the name implies, a string constant pool is used to store strings. It exists in the Java heap memory.Explains how a string pool exists in Java heap space and when we use different ways to cr

solves this problem for us. After the online pool submits the callable task, a future object is returned, using which we can know the status of the callable task and get the result of the execution callable returned. The future provides a get () method so that we can wait for callable to end and get its execution results.What is Futuretask?Futuretask is a fundamental implementation of the future, and we can use it with executors to handle asynchronous tasks. Usually we do not need to use the Fu

? What is Futuretask? How to wake up a blocked thread? How do immutable objects help with multithreading? What does multi-threaded context switching mean? What thread scheduling algorithms are used in Java? What is the role of Thread.Sleep (0)? What is the Java memory model, which areas are thread-shared, and which are unshared What are optimistic and pessimistic locks? Why do I synchroniz

JAVA back-end test questions (1), java back-end test questions The weather turns cloudy on January 1, June 7, 2017. Good mood. I took my first test last Saturday. I felt very bad. I did

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