core java interview programs

class, which usually causes them to stop executing and to wait for a lock on the object.136, what is a thread pool? Why use it? Creating threads takes expensive resources and time, and if the task is to create a thread, the response time is longer and the number of threads a process can create is limited.To avoid these problems, when the program starts, it creates several threads that respond to processing, called the thread pool, which is called a worker thread.Starting with JDK1.5, the

DumpThread dump dumps the memory data (such as the call stack of the thread) that is related to threads. Thread dump is sometimes a javacore, but it seems that Javacore is an IBM virtual machine.GeneratedYou can use your own jstack generated Thread dump: jstack AnalysisThread dump is a text file format, open view directly. Intellij idea provides an analysis of Stacktrace, which we can use to analyze thread dump, which makes it easy to know where a thread is running. Open Intellij IDEAD -> Analy

JDK "Java Development Kit": Java Developer kitJRE "Java Runtime Environment": Java Runtime EnvironmentJVM "Java Virtual machine": Java VMJRE: The runtime environment, including the core

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 interview, I felt quite dissatisfied. I still had to wa

in the heap instead of the stack, using the final decoration.46. What is GC? Why do you have a GC?GC is the meaning of garbage collection (Gabage Collection), memory processing is where programmers are prone to problems, forgetting or wrong memory recycling can cause program or system instability or even crashes, The GC functionality provided by Java can automatically monitor whether an object exceeds the scope to achieve the purpose of automatically

attention to the bottom of the implementation, the novice programmer as long as familiar with the basic use of methods, you can quickly develop on-line; but for senior programmers, the practice of internal strength is more important , such as algorithms, design patterns, underlying principles, and so on, only after these basic proficiency, in the development process can know its why, when problems can quickly locate the nature of the Problem.For Java

threads in sync. There are two ways to synchronize operations, method synchronization, and code block synchronization. When the Synchronized keyword is added to a method or block of code, it means that when a thread executes here, the object's lock is obtained first, and if the object is not locked, the thread adds a lock to the object and continues execution. While other threads are executing here, because the object is already locked, these threads will only wait for the lock on that object t

Java operating mechanism the JVM of the core mechanism The JVM is the runtime environment for Java programs The JVM is part of the JRE, it is a fictitious computer, or it can be understood that the bytecode file is interpreted as a machine instruction on a specific platform when the byte code file is executed by the

The topic comes from http://www.codeceo.com/article/201-java-interview-qa.html, the answer oneself search on the net, if have omission, welcome treatise. Learn together and make progress together. I. Java Fundamentals1. Why is the string class final? 2. HashMap The source code, the realization principle, the bottom structure.3. Tell me about some of the

1. What is Spring? Spring is an open source development framework for Java enterprise-class applications. Spring is primarily used to develop Java applications, but some of the extensions are for Web applications that build an EE platform. The Spring framework goal is to simplify Java enterprise application development and promote good programming practices thro

1. Question: What happens if the main method is declared private?Answer: Can compile normally, but will prompt "Main method is not public" when run.2. Question: What is the difference between a reference and a pass in Java?Answer: A pass-through refers to an address rather than the value itself, and a pass value is a copy of the passed value.3. Question: What else to consider if you want to override the Equals method of an object?Answer: Hashcode.4. Q

Alibaba JAVA Development interview FAQ Summary 4Three main features of java Encapsulation, inheritance, and PolymorphismDifferences between abstract classes and interfaces Java Abstract class:Classes modified using the abstract keyword are called abstract classes.Abstract methods are called abstract methods.Features:1.

initialization, expansion, the bottom why to use the array to add the list of red and black trees, what is the red black tree, the majority of companies will test, see your ability.10 DatabaseIndex, required, based on B + Tree, unique index, normal index, Federated Index, join whether to invalidate the index, the leftmost principle of the federated index, two fields with a federated index, two with, or the first field, query, will not be implemented, with the right field, invalidation, and so o

Java Interview Essentials Summary Set2018-08-11Turn from: Java interview key points summary setArticle Directory1.Basic article1.1.Basic1.2.Collection1.3.Thread1.4. lock mechanism 2. core 2.1. Datastore 2.2. cache use 2.3. Message Queuing 3. frames 3.1.spring 3.

simplifies error handling strategies.1.5. How many modules are there in the Spring Framework, and what are they?Spring Core Container – this layer is essentially the core of the spring Framework. It contains the following modules:Spring CoreSpring BeanSpel (Spring Expression Language)Spring ContextData Access/integration – This layer provides support for interacting with the database. It contains the follo

Java's three technology platforms: Javase, Java EE, javameJdk:java Development Kit, the core of the entire Java, including Java compilers, running tools, etc.Jre:java Runtime enviroment, Java operating environmentpath: Where to store Java's compilation and run toolsclasspath

　 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 Java

Recently, the developer headlines shared a "Xiaomi Java second Round", a lot of Java programmers expressed great interest.I will share with you the second round of Millet Java (Huawei Java Engineer Written test paper can see the end of the article):0, talk about the understanding of spring1. Inheritance relationships f

, and what are they? ①, Spring core container – this layer is essentially the core of the spring Framework. It contains the following modules: Spring Core Spring Bean Spel (Spring Expression Language) Spring Context ②, data access/integration – This layer provides support for interacting with the database. It contains the following modul

more flexible because they do not have any implementation code. After a class implements an interface, this class implements all the methods and attributes in the interface, and the attributes in the interface are under the default state are public static, and all methods are public by default. A class can implement multiple interfaces. 3. Advantages and principles of garbage collection. Two recovery mechanisms are also considered. A notable feature of Java