java programming quiz questions and answers

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

-threaded access to shared resources, due to improper access, usually a thread locked a resource A, but also want to lock resource B, and in another thread, the lock resource B, but also to lock resource A to complete its own operations, two threads want the other's resources, Instead of releasing their own resources, two of threads are waiting for a situation that cannot be performed.Java Network Programming approximate process:UDP programmingSend si

multithreaded programs, multiple threads are executed concurrently to improve the efficiency of the program, and the CPU does not go idle because a thread needs to wait for resources. Multiple threads share heap memory, so creating multiple threads to perform some tasks is better than creating multiple processes. For example, Servlets is better than CGI because Servlets supports multithreading and CGI does not support it.How does the volatile keyword work in

The first one discusses object-oriented programming and its features, common questions about Java and its functionality, Java collection classes, garbage collectors, this chapter focuses on exception handling, Java applets, SWING,JDBC, remote method Invocation (RMI), servlet

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

example, a landing page, using the PO mode, will create a LoginPage class, the class will define the user name input box, password input box, login button webelenentFor the corresponding element to implement the corresponding method, the input box is used to input, you need to create a user name and enter the password method, so that the real page consistent, so the design concept is PO mode. The pagefactory belongs to the PO mode, which is used to initialize the page Class of each PO pattern i

to Wangwei"$ Java-jar Blockchain-java-jar-with-dependencies.jar-add "Send 3.5 BTC to Wangwei"Print Blockchain$ Java-jar Blockchain-java-jar-with-dependencies.jar-printSummarizeIn this article we implement the Blockchain storage function, next we will implement the address, transaction, wallet, some of the functions of

statement in try {}, so will the code in finally {} following this try be executed? When will it be executed, before or after return? Will be executed and executed before return. 28. Programming question: How can I calculate 2 by 8 in the most efficient way? Programmers with a C background are particularly fond of asking such questions. 2 29. The two objects have the same value (X. Equals (y) = true), but

Java Multithreaded interview questions 1. What is the difference between processes and threads? A process is a stand-alone (self contained) operating environment that can be viewed as a program or an application. A thread is a task that is performed in a process. The Java Runtime environment is a single process that contains different classes and programs. Thre

return statement in try {}, so will the code in finally {} following this try be executed? When will it be executed, before or after return? Will be executed, before return. 　　 28th. Programming question: how many equals 2x8 in the most efficient way? Programmers with a C background are particularly fond of asking such questions. 　　29th, the two objects have the same value (X. Equals (y) = true), but diffe

? 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

overloading. 25th, can you inherit the string class? The string class is a final class and therefore cannot be inherited. 26th, when a thread enters an synchronized method of an object, can other threads enter other methods of this object? No, one synchronized method of an object can only be accessed by one thread. 27th, there is a return statement in try {}, so will the code in the finally {} after this try be executed, when it is executed, before or after it? Will execute, before return.

. TreeSetthe largest and smallest elements can be obtained from. Summary: Collections.sort() provides a list that is sorted once. PriorityQueueand TreeSet Dynamic maintenance of the ordered collection.9. Copy ListThere are two ways to copy a list. One is to use a ArrayList constructor. 1 ArrayListnewArrayList The other is to use Collections.copy() . 12 ArrayListnewArrayListCollections.copy(dstList, srcList); It is important to

we don't want to repeat, we should use set. (2) Some collection classes allow the initial capacity to be specified, so if we can estimate the number of storage elements, we could use it to avoid a hash or resize. (3) Based on interface programming, rather than on implementation programming, it allows us to easily change implementations later. (4) Always use type-safe generics to avoid classcastexception

thread in the ready state by dispatching it to occupy the CPU and turn it into a running state. At this point, the system actually executes the thread's run () method.④ Blocking and waking threadsBlocking state (Blocked): A running thread enters a blocking state when it cannot continue running for some reason. These reasons include:(a) When a method of blocking type such as sleep () of a thread object is executed, the thread object is placed in a block set and waits for a timeout to automatical