java interview questions multiple choice

JAVA engineer interview questionsZookeeper I went to a company for an interview today. I felt dizzy with my brains. I didn't make a few algorithm questions. The questions were relatively simple. I should have prepared myself, but the status was not good, after the

1.Volatile and synchronized different points(1), volatile can only be used for variables, the use of a small range. Synchronized can be used in variables, methods, classes, synchronous code blocks, etc., the scope of use is relatively wide.(2), volatile can only guarantee visibility and order, can not guarantee atomicity. The visibility, order and atomicity of synchronized can be certified.(3), volatile does not cause thread blocking. Synchronized may cause thread blocking.Atomicity, visibility,

-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 side:1, create the Socket object constructor Da

Analysis and Summary of Baidu Java R D interview questions 1. Analysis of Common application scenarios in singleton mode. Among the 23 design modes, the singleton mode is the largest. It is easy to understand, but applicable to scenarios. Are you really familiar with this? The use of Singleton is because there is no need to create an object for each request, wh

Java multi-thread interview questions 1. What is the difference between ArrayList and Vecoter? Similarities and differences between Array and ArrayListI. Differences between Array and ArrayList#1. variables of the Array type must be instantiated at the same time (at least the size of the Array must be initialized), while ArrayList can only be declared first.For e

, StringBuilder and StringBufferStorestring constant, which cannot be changed once the object is createdStringBuilder and StringBuffer: String variables, objects can be changedExecution speedstringThread SafetyString,stringbuilder is thread insecure, StringBuffer is thread-safe.Scope of applicationString: Applies to a small number of string operationsStringBuilder: For a single thread, large number of string operationsStringBuffer: For multi-threading, a large number of string operations3. Singl

need to lay the foundation, the IDE select one to understand.2. Study the idea of Java programming"Thinking in Java" This book is the Great God highly recommended books, since the great God recommended, we might as well study it.It does not guarantee that you are out of the new ranks, but will lead you to the path of master.3. Learning: HTML, CSS, JavaScript, JQuery, BootstrapIn addition to learning

As a Java programmer who is often asked in an interview, let me summarize some of the questions that I often don't ask. The difference between 1.HashMap and Hashtable Often asked. Both are classes of the map interface, which enable you to map a unique key to a specific value. HashMap class is not sorted and can have a null key and

Do not write any scopes (that is, access rights) represent friendlyPublic, the largest, the largest scope, within the class, the same package, descendants class, other package can be accessedProtected protection, can be accessed within the class, the same package, descendant classes, but other package cannot accessFriendly friendly, within the class, the same package can be accessed, descendant class, other package cannot accessPrivate, minimal permissions, minimal scope, access within the class

values that cannot be changed. The string provided by this StringBuffer class is modified. You can use StringBuffer when you know that character data is going to change. Typically, you can use Stringbuffers to dynamically construct character data.5. What are the similarities and differences between abnormal operation and general anomaly?An exception represents an unhealthy state that may occur during a program's run, and a run-time exception that represents an exception that may be encountered

are characterized by the inability to define variables, and all methods are abstract methods . abstract classes can have variables and do not enforce the need for abstract methods .Inheritance of class 16 and implementation of interfacesParsing: Class Inheriting the parent class implements the interface with the class, which is essentially the same. is to either extend or rewrite the parent class or interface as a template on this template. In practical programming, programmers often need to in

Java Architects interview questions, how to become architectsOften interview some candidates, sorted out my interview using the topic, LU continued to organize a lot of problems, so each time to draw a part to ask. The answer will be gradually released in later articles. B

Translation Links: http://www.codeceo.com/article/java-hashmap-value-sort.htmlThe English version: How to Sort HashMap Based on the Values in JavaTranslation Author: Code Rural network – Xiao Feng HashMap in Java is a data structure for storing "key" and "value" information pairs. Unlike array, ArrayList, and linkedlists, it does not maintain the order in which elements are inserted. Therefore, sorting hash

Java interview questions: Implementation of stacks and queues During the interview, stacks and queues are often checked in pairs. This article includes the following stack and queue test content: 1) stack Creation 2) create a queue 3) Two stacks implement one queue 4) two queues implement one stack 5) design the stack

ImportNew Note: This article is one of the Java interview series compiled by ImportNew. You can view all the Java interview series from here. The common Interview Questions introduced in this article are about the overloading meth

picture suffix 2, how to suffix is tampered with, then each file has a magic digital file upload-magic number5, the principle and implementation of Message Queuing Answer: 1, Message Queuing Principle 2, comprehensible message queue ActiveMQVi. Database Aspects1. The MySQL query field area is not case-sensitive?Answer: Do not differentiate, even if the value is not differentiated (I asked at the time, the area of the application of the size of the meaning of what, the interviewer did not say)2,

the length expands, the hash rules change as well. Let's review the hash formula:index = hashcode (Key) (Length-1) When the original array length is 8 o'clock, the hash operation is done with the 111B (representing the binary 7), and the new array length is 16,hash and 1111B (representing the binary 15). hash results are obviously different . The Java code for rehash is as follows: /** * Transfers all entries from the current table to newtable.

Analysis of Java interview questions and prevention of SQL injection, semi QL This article focuses on a common question in the Java interview questions, how to judge and prevent SQL Injection problems. The details are as follows.

Test your Java basic test questions: This is a few interview questions I designed. The requirement is that there should be as few questions as possible and they can be completed within five minutes, but it can basically reflect the level of knowledge of the interviewer. So I

;. 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