java coding interview questions and answers for experienced

Java interview questions: how to sort HashMap key values In Java, HashMap is a data structure used to store "key" and "value" Information pairs. Unlike Array, ArrayList, and lists, it does not maintain the order of inserted elements.Therefore, sorting HashMap Based on keys or values is a very difficult

into the corresponding method to invoke the logical layer of the method to achieve response to the customer.There are no doget, dopost, and so on in the Servlet interface and Genericservlet, these methods are defined in HttpServlet, but all return error information, so, each time we define a servlet, Must implement these methods such as Doget or Dopost.Each custom servlet must implement the Servlet interface, and the Servlet interface defines five methods, of which the more important three meth

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

Java multithreading interview questions Induction1. What are the implementation methods for multithreading? The following example shows the thread synchronization. (1) Java multithreading has two implementation methods: Inheriting the Thread class and implementing the Runnable interface. Thread implements the Runnable

(throughput) collector?The throughput collector uses a parallel version of the new generation garbage collector, which 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.7. In Java, when can objects be garbage collected?This object can be recycled when the object becomes inaccessible to applications that currently use the o

. At the same time if there are multiple threads accessing Hashmap,collections.synchronizedmap () can be substituted, generally hashmap more flexible.10. Why is the vector considered to be obsolete or unofficially deprecated? Or why we should always use ArrayList instead of vectors.You should use ArrayList instead of vectors because by default you are non-synchronous, vectors synchronize each method, you almost never do that, and usually you want to synchronize the entire sequence of operations.

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

Sword refers to Java Implementation of offer programming questions -- interview question 4 replaces spaces, and sword refers to offerImplement a function to replace spaces in a string with "% 20 ". For example, if the string is We Are Happy, the replaced string is We % 20Are % 20 Happy. 1 package Solution; 2 3/** 4 * offoffoffer

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 Algorithm interview questions: Write a Singleton, javasingleton Package com. swift; public class Singleton {public static void main (String [] args) {/** write a Singleton */ORC_Hungry.getOrc (). fun (); ORC_Lazy.getOrc (). fun () ;}} class ORC_Hungry {// hungry Chinese private static ORC_Hungry orc = new ORC_Hungry (); private ORC_Hungry () {} public stati

longer executed.(2) But in the case of a hash collision, the first two conditions are established, and then the last equals must be used to determine the equality of the objects.A 3.hash collision scene?(1) Generally appears in large data situations(2) The generation method of Hashcode is weak (such as the artificial production hashcode above)Summary: This chapter mainly through the introduction of hash collision once again in-depth understanding of hashmap work principle.This chapter is here,

1. The difference between String and StringBufferThe Java platform provides two classes: string and StringBuffer, which can store and manipulate strings, That is, character data that contains more than one character. This string class provides values that cannot be changed strings and the strings provided by this StringBuffer class are modified when you know that character data is going to change, you can use StringBuffer typically, You can use Stri

Difference between Forward and Redirect in common JAVA interview questions, forwardredirect The user sends an HTTP request to the server, which may be returned to the user after being processed by multiple information resources. Each information resource uses the request forwarding mechanism to forward requests to each other, however, the user does not feel reque

One: The difference between Eclipse and MyEclipseA: 1 common: Both are used to develop Java projects, and software usage is almost identical2 MyEclipse is a fee-free software, which can develop both Java and Web projects, Eclipse can only develop Java projects, if you want to develop a Web project, but also need to add additional Eclipse Web plug-in (of course, c

default branch, which must be the last branch of a switch statement. (3) default is executed when no case statement is equal to the value of the variable. The default branch does not require a break statement.Break is used to interrupt the loop statement, and continue is used to continue the loop. Breake break out of the loop body, continue continue the next loop, but the statement after continue is not running. Continue can only be used in loop statements, and break may be used in other branch

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 multiple nul

The resume has some Ajax and struts issues.Growth strategy for database primary keyThe type of struts?Why use the difference between struts;session and cookies,Introduction to AjaxWhat are the built-in objects for 1.jsp?Four scopes for 2.jsp3. "". What is the difference between equals A and A.equals ("")?What is the difference between get and post for a 4.form form submission?What is the difference between 5.Cookie and session?How do 6.mysql and Oracle's primary keys come into being?7. Why use S

position, filling the original AI (i), the AI value inserted into the space after the shift of J * * This implementation of a card from I, inserted into the exact position. Loop through the process sequentially, and each element of the loop is eventually inserted into the position it should be in, thus sorting is achieved. * [1, 2, 4, 5, 6, 7, 9, 3, 8] * [1, 2, 3, 4, 5, 6 , 7, 9, 8] * @param array * @param up */Public static void Insertsort (Int[] Array, Boolean up) {for

(); - } - - Public BooleanIsEmpty () {///Bottom call is LinkedList's IsEmpty () method to determine if the set internal data is empty - returnlink.isempty (); in } -}(2) test of Mystack:1 Packagecn.itcast_05;2 3 /*4 * Test of Mystack5 */6 Public classMystackdemo {7 Public Static voidMain (string[] args) {8 //To create a collection object9Mystack ms =NewMystack ();Ten One //adding elements AMs.add ("Hello"); -Ms.add ("World"); -Ms.add ("