object reference

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Java's synchronized keyword: Summary synchronization mechanism

JAVA is a function of the synchronized keyword can be used as modifiers, but also as a function of the statement, it is usually said synchronized method and synchronized block. Find out which object is synchronized lock, you can help us to design mor

Common abnormalities resolved

ConcurrentHashMap and CopyOnWriteArrayList comparison. Blog categories: Java ConcurrentHashMap ConcurrentHashMap introduced Segment, each Segment is a hashtable, the equivalent of two Hash table, and then lock in the Segment level, and increased concurren

September 2 (summary page)

1 problem: TypeError: Error # 1009: can not access a null object reference property or method. Cause: When a NavigatorContent flex sequence after the first, followed by implementation of NavigatorContent no longer active, did not generate the impleme

Decorator (Parcel Mode)

Decorator paint brush painter's image understanding. Is the role of painter decorator, who was decorated by brush device role. Decorator in four roles The role of abstract components: additional features of an abstract interface. That is to be de

Java String object, the classic problem of (new String ()) [switch]

Look at an example, the code is as follows: Java code public class Test { public static void main (String [] args) { String str = "abc"; String str1 = "abc"; String str2 = new String ("abc"); System.out.println (str == s

Understand Session caching mechanism to manipulate persistent objects

Hibernate provide us with the main interface to manipulate the database, Session is one that provides the basic add, delete, change, methods, but also has a caching mechanism, in accordance with a certain point in time, according to the persistent ca

Memcached distributed caching system study

A, Memcache Profile Memcache is danga.com a project, the first for the LiveJournal service, many people around the world currently use the cached items to build their own big load of sites to share a database of pressure. It can cope with any number of co

subversion learning two

On non-Windows platforms, Subversion can version of a symbolic link, a symbolic link to another file system is transparent object reference, through the symbolic link operations, the changes object can be achieved SVN commonly used to modify the dire

[Transfer] JavaScript Core Guide (JavaScript Core)

Transfer from: http://dmitrysoshnikov.com/ecmascript/javascript-the-core/ (Gray often read like the English original, but unfortunately English is entangled. To find the weak weak translation. Recommended for good or go directly to the English giant above

Some knowledge of Flex summary of garbage collection

Some knowledge of Flex garbage collection summary: 1, deleted all references to objects in the external must be removed as a clean garbage collection system in order to be disposed of. 2, the parent child object is outside the internal references to other

[Original] Flash's garbage collection and memory leak

ActionScript3.0 garbage collector positioning using two methods without reference to the object reference count and identify the clear method. Reference counting, an object used to track the activities of a relatively simple method, which started from the

RegExp - regular expressions

RegExp class allows the use of regular expressions (can be used to perform a search and replace string in text mode). You can use new RegExp() RegExp constructor or assigned to a variable text to create a new RegExp object: var pattern1:RegExp = new RegEx

Summary 4 Android mobile development TIPS

A good example of a handler public static final int UPDATE_DATA = 0; / / constant update data on behalf of public static final int UPDATE_COMPLETED = 1; / / constant update data on behalf of TextView tv; / / TextView object reference Button btnStart; / /

Commonly used functions and commands

is, is not = id (...)== id (...) # is the same object reference comparison >>> Import cat >>> C1 = cat.Cat ('c', 4) init cat, name is c; age is 4 >>> C2 = c1 >>> C3 = cat.Cat ('c', 4) init cat, name

What is application domain? What is a controlled code? What is managed code? What is a strong type system? What is boxing and unboxing? What is overloading? CTS.CLS and CLR, respectively, be interpreted?

Application domain for the security, reliability, version control, and uninstall the assembly provides isolation boundary. Application domain is usually created by the runtime host, the runtime host before running the application is responsible for guidin

js in the delete operator

Javascript variables Javascript in fact, the variable = object properties, because before the Javascript in the script will create a Global object, all the global variables are the Global object's attributes, execution of a function will create a Acti

Java Interview data type

Java, the type can be divided into two categories, one is the original type, one is a reference type. In addition, java provided for each primitive type wrapper classes. There are many differences between them. As follows: 1. Declaration stored conte

Java Memory Allocation

Stack, heap, although both belong to the constant pool of Java memory allocation operations area, but use very different scope and function, this in-depth Java core gave a detailed knowledge of Java memory allocation. Java memory allocation and manag

as3 load film TypeError: Error # 1009: can not access a null object reference property or method

Encountered a problem today: A swf file, in the main file to load the swf, but it has encountered the following problems: When performing loadSwf ("xxxx.swf") after the error TypeError: Error # 1009: can not access a null object reference p

Effective Java 2nd edition

Item 3: Enforce the singleton property with a private constructor or an enum type While this approach has yet to be widely adopted, a single-element enum type is the best way to implement a singleton. have yet to is a phrasal verb, like Certain quest

(Int) Int32.Parse () Convert.toInt32 () (turn)

In C #,, (int), Int32.Parse () and Convert.toInt32 () three methods differ? int keyword denotes an integer is 32 bits, it's. NET Framework type is System.Int32. (Int) that the use of an explicit cast, is a type conversion. When we type from int t

c # difference between reference types and value types

C # value types include the basic types (with the keyword int, char, float, etc. to declare), structure (declared with the struct keyword type), enumeration (declared with the enum keyword type); and reference types, including type ( declared with th

Baby ducks learn Ruby-18. Object

Object Objects Ruby is purely object-oriented language: all values ​​are objects, and there is no fundamental difference between types and object types. Object all objects inherit from a class, share such a method 1, the object reference used in the Ruby

The Mysql storage engines used

The following are the most commonly used storage engine: ◆ MyISAM: default MySQL pluggable storage engine, it is in the Web, data warehousing and other application environments one of the most frequently used storage engine. Note that by changing the

uml aggregation associated with generalized dependence

Multi-state: A name, many forms. Based on integrated multi-state. Call a method, according to the different objects of different treatment options. Runtime binding Association: When one object to another object reference to another object using the s

Materialized view query rewrite constraints [Reserved]

Materialized view is an important feature is support for query rewrite. If the initialization parameter query_rewrite_enabled set to TRUE, and the CBO, when issuing the query on the base table, Oracle will automatically determine whether the use of t

Scorm1.2 difference with Scorm2004

The main difference is: teaching rules. January 30, 2004, Advanced Distributed Learning organization released the 2004 latest Sharable Content Object Reference Model (SCORM2004), formerly known as SCORM1.3 version. SCORM2004 version of the focus? Ent

Can not change the object reference to the lock

import java.util.logging.Level; import java.util.logging.Logger; /** * * @author max * You can modify the contents of the lock, but the locks cannot be modified refer */ public class TestNotify{ static Boolean lock = true; // static A lock = new A(1)

End of the year finishing eight engine MYSQL

Display engine commands to get a list of available engines show engines Install mysql when you can choose to use myisam format, rather than the default innoDB. If you want to have already installed the mysql server to change the default storage engin

On the transformation of the object - my errors

Polymorphism of three forms: 1. Class of Multi-state (achieved through inheritance) 2. Methods polymorphism (method override, method overloading: the number of the parameter list, to distinguish between different types) 3. Dynamic linking (as defined

Effective Java notes (c)

NO.7 override equals method in general agreement, please observe the following conditions do not need to rewrite the equals method is: 1. Different instances of the same class is unique in nature, that is, instances have their own body (Identify). 2.

Android to avoid memory leaks (translation)

Android application memory is limited to 16MB, at least in G1 phone is. For a mobile phone, it has occupied a lot of memory, but the developers want to achieve, these memory is very small. Even if you did not intend to use up all the memory, but you shoul

The usage of Hibernate's cascade attribute

Cascade property value: none: the save, delete, modify the object, without regard to the operation of its appendages save-update: In the save, update the current object, cascade save, update the appendage. delete: delete the current object, the cascade de

automatically instantiated struts2 problems

Quoted from http://longtangwan.javaeye.com/blog/641695 Quote Domain objects used to receive user input er object contains two fields: username and password, a User in the Action objects in the user, then in the jsp in: Jsp code <input type="t

[Transfer] AS3 garbage collection Detailed

AS3 function relative to the previous version of the much enhanced, when the task entrusted to it, it must also pay a price: the garbage collector will not support automatic garbage collection for you. This article, I compiled some information for everyon

[C #] DBNull.Null and the difference between String.Empty

The interpretation of DBNull: This class does not exist to indicate a known value (usually in a database application.) In a database application, null object is a valid value for the field. Class distinction between null (empty object) and uninitialized v

Review the internal java class

Within the class definition: a definition of the class in another class. The role of inner classes: Within the definition of class methods can access the class where the scope of the data, including private data. Within the same class of other classe

Static factory method

It is just a simple static method that returns an instance of the class. 1. And structural function, the static factory method name. Choose the appropriate static factory method name can make a class easier to use, and the corresponding client code e

java foundation - reflecting

Reflection is a low-level programming, in order to solve the general programming. (Write a method printMethods, parameter is a string className, pass a class name, this method to a class which method to print out.) Learning reflection of the most cri

[Transfer] Flex performance optimization project

http://nianshi.javaeye.com/blog/836432 Some knowledge of garbage collection summary: 1, deleted all references to objects in the external must be removed as a clean garbage collection system in order to be disposed of. 2, the parent child object is outsid

[Transferred] to improve application performance 10 Flex Tips

http://nianshi.javaeye.com/blog/812470 Rule # 1: Cleaning the code Generally speaking, keep the code clean is a good habit. This is not just writing the code is neat and has good readability, and have to not leave any burden, such as: memory leak, cp

Java memory management

1.Java memory management mechanisms include: memory allocation and garbage collection, this work is done with JVM; 2. When an object reference JVM will automatically lose its recovery; 3.JVM directed graph used to manage objects in memory; 4. Strong

Equivalence of test object and equivalence

public class qwe{ public static void main(String[] args){ Integer n1=new Integer(47); Integer n2=new Integer(47); System.out.println(n1==n2); System.out.println(n1!=n2); } } Results: false true Solution: Because the two Integer objects are the same.

Java memory allocation. Management Summary ---- reserved

Articles Category: Java Programming Transfer from: http://java-mzd.javaeye.com/blog/848635 Wanted to write this summary brewing for months to come there, and has always felt something was nearly always dared not write. Two days of fighting last night to r

Java memory allocation management

http://java-mzd.javaeye.com/blog/848635 PS Wanted to write this summary brewing for months to come there, and has always felt something was nearly always dared not write. Two days of fighting last night to refresh the data under the previous inspection, n

preloading flex problem

I proloading AIR encountered, TypeError: Error # 1009: Cannot access a property or method of a null object reference. at spark.components:: WindowedApplication / enterFrameHandler () [E: \ dev \ 4.x \ frameworks \ projects \ airspark \ src \ spark \

Research Questions Asked

Thoroughly understand a java value is passed The value of the basic data type is passed, Java language, object passed is the address, not a reference, these two concepts have a very big difference, I believe people who are familiar with c + + should

servlet's init method

Servlet init method is executed after instantiated, and only once. One. Start with init (ServletConfig) in the parameter ServletConfig, represents the configuration information. That is configured in the web.xml information, such as: <servlet>

Detailed oracle stored procedure - to achieve by the cursor. Delete. Change. Check function

Cursor (CURSOR) is the ORACLE system opened in memory of a work area, in which the stored query results returned by the SELECT statement. The query results can be either zero records, single records, multiple records can be. In the work area defined by th

The error occurs because the application server Analysis

Disk full system will not function properly, the most likely reason is that the disk is full. A good network administrator will be closely monitoring disk usage, separated some time, you need to dump some load on the disk backup storage media (eg tape). A
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