java application performance tuning interview questions

using outer joins, the number of SELECT statements is few;Disadvantage: 1 May load objects that the application does not need to access, wasting a lot of memory space; 2 Complex database table connections can also affect retrieval performance; 5, how to see the SQL that hibernate builds and executes on the console In the file applicationconfig.xml that defines the database and database properties, set the

Whether you care or not, Java Web applications use a thread pool more or less to process requests. The implementation details of the thread pool may be overlooked, but the use and tuning of the thread pool will need to be understood sooner or later. This article mainly describes the use of the Java thread pool and how to properly configure the thread pool. Singl

Frontier Dream Workshop 2017-04-18 18:14 Most of the Java interview is divided into written and interview, the following issues are cutting-edge education small series according to the major IT enterprises interview asked the questions sorted out, such as the need for releva

finalize () method to sort system resources or perform other cleanup tasks. The finalize () method is called before the Garbage Collector deletes an object. Second, can anonymous inner class (anonymous internal class) be extends (inherited) other classes, or implements (implemented) interface (Interface )? An anonymous internal class is an internal class without a name. It cannot be extends (inherited) other classes, but an internal class can be used as an interface and implemented by another i

Javamelody can monitor Java or Java EE application servers in a running environment. And graphically displays: Java memory and Java CPU usage, number of user sessions, number of JDBC connections, and number of executions of HTTP requests, SQL requests, JSP pages and Business

. 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.

I used to have only one Java interview question topic. Now I have divided into the following topics: Java interview questions are of course the focus, all of which are Java programming and directly related to the design. Intelli

1. What is acitsag startup mode? For such a question, I will write an example myself. I will observe it to understand it. Activty supports four startup modes. Launchmode: Standard: each time a new activity window is started (New Operation) Singletop: if it is a target activity at the top of the stack, It will be opened directly. Otherwise, a new activity window (new) will be opened ). Singletask and singleinstance are basically the same. The difference is that if the root activity is set to sing

Java Questions Answers 1. What is the difference between an applet and an application? A Java application is made up of a main () method declared as public static void that accepts a string array argument, along with any other classes that main () CILS. it lives in the env

Huawei's Java interview questions Question No: 1 1. Public class test { Public static void changestr (string Str ){ STR = "welcome "; } Public static void main (string [] ARGs ){ String STR = "1234 "; Changestr (STR ); System. Out. println (STR ); } } Please write the output result: Question No: 2 1. Public class test { 2. Static Boolean Foo (char c ){ 3. syst

space operation is the fastest but also very small, usually a large number of objects are placed in the heap space, the entire memory, including the hard disk of virtual memory can be used as heap space.String str = new string ("Hello");In the above statement, STR is placed on the stack, the string object created with new is placed on the heap, and the literal "hello" is placed in the static storage area.Supplement: A technique called escape analysis is used in newer versions of

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

in February. The first day of 1751 in England was March 25, 11 days worse than France.After the United States adopted the Gregorian calendar, it went back hundreds of years, so that the dates originally recorded could be expressed in two calendars (usually to provide two dates for more precise purposes). For example, George Washington's birthday changed from February 1731 11 to February 1732 22.When you read a volatile variable in a thread, you can eventually read the value that it updated.A f

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

Dark Horse programmer ---- java-based operators, keyboard input, if switch statements, related Interview Questions, ---- javaswitch ------ Java training, Android training, iOS training, and. Net training. We look forward to communicating with you! ------- 1: Operator (master)(1) Arithmetic Operators A: +,-, *,/, %, ++

Java interview questions Basic knowledge:1. simple principles and applications of the Exception Handling Mechanism in C ++ or Java. When a Java program violates the Java Semantic Rules, the Ja