core java interview questions and answers

Java learning path-simple basic interview questions, java path-Questions 1. What are the features of object orientation? A: The object-oriented features mainly include the following: 1) Abstraction: Abstraction refers to the process of summarizing the common features of a cl

generates a number that requires all of these numbers to be generated between 1-1000w. (Study high efficiency, solve the problem of conflict)2. Merge sort of two ordered arrays3. Reverse of an array4. Calculate the positive square root of a positive integer5. It is common to look at the sorting algorithm (sort reprint: http://mp.weixin.qq.com/s?__biz=MjM5MTAzMTE4Nw==mid=204838393idx=2sn= E9B50C8EF689E2CB6436110A8DC148A3SCENE=5#RD)Nine, Cache1. Why cache, which caches are used, the difference be

supports the removal of elements through the iterator remove, Set.remove, RemoveAll, Retainall, and clear operations and removes the corresponding mappings from the map. It does not support add and addall operations. (3) set Returns a collection view of all mappings contained in a map clock. This collection is supported by the map, which is reflected in the collection and vice versa. When an iterator is traversing a collection, if the map is modified (except for the entry of the iterator itsel

What is value passing and reference passing A value pass is a basic variable , and a copy of the variable is passed. Changing the copy of course does not affect the original variable.Reference passing is generally for object-type variables . The memory address of the reference object is passed What are the thread states, and how are they converted? The difference between a thread and a process, what are the pros and cons What are the effects and costs of indexing? How do I

execution.Surround notification is one of the most common types of notifications. Most interception-based AOP frameworks, such as Nanning and JBOSS4, provide only surround notifications.The concept of pointcut (pointcut) and connection point matching is the key to AOP, which makes AOP different from other old technologies that simply provide interception functionality.The pointcut enables the location notification (advice) to be independent of the OO hierarchy. For example, a around notificatio

is used for medium-sized and large-scale data applications. The serial collector is sufficient for most small applications, which require about 100M of memory on modern processors.41. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the object.Is there a garbage collection in the permanent generation of 42.JVM?Garbage collection does not occur in a perma

classifies frequently-encountered computer programming questions, hoping to help and inspire readers. Chapter 1 thinking and Intelligence Testing 18th this type of interview questions puts forward higher requirements for the interviewer. Questions about thinking expansion can be divided into two categories. One is thi

the two tags, 115. What does the implied object mean? What are the hidden objects?JSP implied objects are some Java objects in the page, and the JSP container allows these Java objects to be used by developers. Developers can use them directly without a clear statement. JSP implicit objects are also called predefined variables. The following lists the implied objects in the JSP page: Application

One of the interview summaries: Java handles linked list questions during the interview and java handles themThe linked list is often used in interviews. This article has referenced some other articles and added my own summary. Basically, every algorithm has been tested and

between the two tags, 115. What does the implied object mean? What are the hidden objects?JSP implied objects are some Java objects in the page, and the JSP container allows these Java objects to be used by developers. Developers can use them directly without a clear statement. JSP implicit objects are also called predefined variables. The following lists the implied objects in the JSP page: Appli

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, and JSP. Exception handling

("Too big, a little bit smaller");}else{System.out.println ("Congratulations on your guess right");Break}System.out.println ("remaining" + (10-A) + "Second Chance");}while (true);}}　　4. use a double loop to print all the primes between the 2~200. public class Text {public static void Main (string[] args) {for (int i = 2; i Boolean A = true;for (int j = 3; J if (i%j==0) {A = false;Break}}if (a) {System.out.println (i);}}}} An int array is known to arr = {12,4,22,11,24,9}, finding the ma

into uppercase or lowercase.5. How to compare two strings?The comparable interface is implemented internally in String, with two comparison methods: CompareTo (String anotherstring) and Comparetoignorecase (String str). CompareTo (String anotherstring)Compares the passed-in anotherstring string, if it is less than the passed-in string, and returns a negative number if it is greater than the certificate. Returns 0 when two string values are equal. The Eqauls method returns true at this

, how to make a string into lowercase or uppercase form?Use the toUpperCase and toLowerCase methods to turn a string into uppercase or lowercase.5. How to compare two strings?The comparable interface is implemented internally in String, with two comparison methods: CompareTo (String anotherstring) and Comparetoignorecase (String str). CompareTo (String anotherstring)Compares the passed-in anotherstring string, if it is less than the passed-in string, and returns a negative number if it

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

Java interview questions, java questions1. simple principles and applications of the Exception Handling Mechanism in C ++ or Java.When a JAVA program violates the JAVA Semantic Rules, the JAVA