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Arrays.asList returns ArrayList is not a java.util.ArrayList, call the newspaper UnsupportedOperationException

Calling code: String[] tmpIds = ids.split(","); rt = Arrays.asList(tmpIds); rt.add(String.valueOf(userId)); Arrays.asList (tmpIds) returns a fixed-size list /** * Returns a fixed-size list backed by the specified array. (Changes to * the returned lis

On the Arrays.asList (T. .. a)

Arrays.asList () 1.5 with the variable parameters of the new features, such as: int [] num = new int [] {3,5}; List list = Arrays.asList (3,5); List list1 = Arrays.asList (num); System.out.println (Arrays.toString (list)); System.out.println (Arrays.

Sorting an array Arrays.sort (Collection)

package com.j2se.sort; import java.text.RuleBasedCollator; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; public class ArraysSort { public static void main(String[] args) { // intArraySortByAsc(); // stringArraySortByA

Arrays - Thinking in Java

1) There are three issues that distinguish arrays from other types of containers: efficiency, type, and the ability to hold primitives. The array is Java's most efficient way to store and randomly access a sequence of object references. Arrays are sup

java based lists and arrays (2)

Code Analysis: 1.Java way in through the array Through the array methods more, how to traverse, as long as you like, you can. import java.util.ArrayList; import java.util.Iterator; import java.util.List; / ** * Traverse an array of four methods * @ A

On the conversion efficiency between arrays and linked lists

public static void main(String args[]) { List<String> strList = new ArrayList<String>(); strList.add("username"); strList.add("created"); strList.add("disabled"); strList.add("locked"); strList.add("expired"); long begin = System.currentT

ava.util.Arrays and java.util.Collections

First have to know two classes: java.util.Arrays and java.util.Collections (the difference between attention and Collection) Collection is a collection of top-level interface to the framework, and Collections contains many static methods are. We use Array

Unit testing tool JUnit 4

Reproduced to 3A / / / bbs / index.php Unit testing tool JUnit 4 JUnit best practices You intend to put the code on unit testing, what places? Put it and test code mixed toge

Upload file type validation tools

1, define the legitimate file type configuration file gif=image/gif jpg=image/jpg,image/jpeg,image/pjpeg bmp=image/bmp png=image/png swf=application/x-shockwave-flash doc=application/msword txt=text/plain xls=application/vnd

The producer consumer model based on BlockingQueue achieve (that is, use type)

Producer-Consumer model is undoubtedly an important framework for achieving mode ... Code uses the example:

EffectiveJava-variable parameters of Article 42 be used with caution

(1) The variable parameters allow you to pass multiple parameters, or 0, and sometimes lead to confusion Sometimes, we should be a clear need for one or more write parameters of the approach and does not apply to 0. If you are not careful to write su ...

java permission

import javax.swing.JFrame; public class PermissionTest ( / ** * @ Param args * / public static void main (String [] args) ( / / TODO Auto-generated method stub System.setSecurityManager (new SecurityManager ()); JFrame frame = new PermissionTestFrame ...

Classes and interfaces

So that members can access classes and the ability to minimize public that this class is available in any scope. protected means that only sub-classes and packages can be used within the class private-package (default) that is available in the packag ...

IO Flow Review (designated under the specified directory listing format)

Meisha things to do during this time, so it will take a look at programming ideas turn. Under the small study IO, above is the book of exercises, mainly used in the FilenameFilter interface to filter file names. FileFilter class which implements File ...

the set of java objects

Java Basics: A collection of objects (top) 1. Arrays: Arrays and other containers difference is reflected in three aspects: efficiency, type of identification and can hold primitives. Java array is provided that can store and access reference random seque

Generate random numbers from a random value inside an array

A short time ago a friend sent a question, saying that surface examination questions, these days leisurely look at the show. Such as the question: the definition of an integer array, length limited to, value not limited to, asking random number taken ...

In the Eclipse unit testing using JUnit4 (Advanced chapter)

Before the passage of two articles, you are bound to have a basic understanding of JUnit, the following JUnit4 us to explore some advanced features. <!--[ if! supportLists] -> 1, <!--[ endif] -> Senior Fixture Previous article, we introdu ...

java dynamic compilation and run (reproduced)

Compiled by JavaCompiler are generated in the current directory. Class files using compiler option to change the default directory. Compiler option is an element of the String type of Iterable collections. If we can use the following code in D under the r

java String's split method is easy to mistake

Today, a similar split with the split method "1 | 2 | 20,100,312" in the string, using Arrays.asList the String [] turn into a List, the result is that such a [, 1, | 2, |, 2, 0, 1, 0, 0, 3, 1, 2] Encountered this problem many times, search ...

Features of Java 1.5: Variable-length argument function

Java1.5 provides a feature called varargs is the variable-length parameters. In previous versions of the jdk, the object in a method written into the reference number of the post is fixed, while the varargs feature provides a variable-length, somewha ...

java's classloader (2)

Wrote The article was from: This article will introduce more in-depth principle and process of loading java classes, although in many cases you do not need to understand the class loading p ...

Use third-party java class library to generate a pdf and excel Report Object

Mainly used for more than a third-party jar packet itext.jar Is mainly used for more than the jxl.jar

Java: Performance Analysis of collections [change]

This article is transferred, and no verification of the correctness of the article, I have time will be carefully checked, everyone If you have time, you can also help to test, and then the process will be issued with the results look. 1.Java collect ...

From Java in the Set, List, Map leads to sorting techniques

From Java in the Set, List, Map leads to sorting techniques 1. About Concept: List of the Collection interface to a simple expansion, and its concrete implementation classes commonly used are ArrayList and LinkedList. You can be anything into a List conta

Zhang Xiaoxiang J2SE strengthen the self-Notes (17-24)

17, a thorough analysis of the basis of reflection type Class categories: Person p1 = new Person(); Class cls1 = java.util.Date.class // Bytecode 1 Class cls2 = Person.class // Bytecode 2 Class cls3 = p1.getClass() When the. Java source code files to comp

Zhang Xiaoxiang J2SE strengthen the self-Notes (25-40)

25, the application of reflective array: Array utility class used to complete the reflection on the operation of an array Array // Call the following method public static void main(String[] args) { String[] a4 = new String[]{"a","b","c"}; printObject(a4);

Common set of conversion between

1.list transfer set Set set = new HashSet (new ArrayList ()); 2.set transfer list List list = new ArrayList (new HashSet ()); 3. Array to a list List stooges = Arrays.asList ("Larry", "Moe", "Curly"); Or String [] arr = ...

Understanding of Java Collections (4)

List Interface In addition to standard methods inherited from the Collections addition, List the purposes of the definition in its own way: Location to visit the location of access element by element search Search List the specific element and return ...

java collection analysis (2)

pan> Of course, this method is not efficient. If you find that you are using this method, you may be using the wrong data structure to solve your problem. 12-1. If you have an integer index n, then List.listIterator (n) will return an iterator that poi

Effective Java 2 study notes chapter 7 method

Article 38: Check the validity of arguments When you write a method or constructor, it should consider what limits its argument. These restrictions should be written documents, and the beginning of each method, by showing the check to the implementation o

Multiple images using a class to manage, subrequest variables used

public static String className = ManageAssetFacesBean.class.getName (); public static Log logger = LogFactory.getLog (ManageAssetFacesBean.class); public static final String TYPE_CREATE = "create"; public static final String TYPE_COPY = &qu ...

JSP custom tag instance

Definition: a custom tag is a very good component technology. By using a custom tag library, you can label the package in a simple complex Function; To understand: it will JSP page (complex, repetitive and uniform format) content package, instead of using

ibatis single object of all operations

Beginners ibatis, version ibatis-, Jar package required: log4j-1.2.15.jar, ojdbc14.jar. Code has been uploaded, the project does not contain ojdbc14.jar, their combined Kazakhstan. Database oracle10, first of all the various operations on the

JAVA utils Collection array list

1, Iterator (an important interface) Is a unified approach to traverse the elements of the various collections / iteration tools, also known as "iterator." It allows the "traverse" the process of removing the elements of the collection

Java simple assembly algorithm

Old people, memory is getting worse, and trying to find college wrote the code to paste stickers, so as not to have completely forgotten. A permutation and combination with Recursive, I do not know how many characters in the crash

CoreJava learning experience 16

Java5.0 new features Auto-boxing and auto-unboxing Automatic sealing and auto-unboxing, which implements a simple type and package type of mutual transformation, the implementation of automatic conversion. Automatic sealing solution tank when it is only n

Collection and mapping

Collections Framework Overview Is to set a number of purposes, of the same nature, or meet a whole array synthesis. From the system perspective, the collection types can be grouped into three types: Set (Set): Set the collection does not distinguish betwe

java programming source code file operations thought IO6

package com.dirlist; import; import; import; import; public class FileOutputShortcut { /** * The shortcut text file output */ static String file="FileOutputShortcut.out";

velocity study notes

Source Address: Home Java Network Programming Velocity note Friday, at 9:09 on the January 15, 2010 "Velocity will be Java code from Web pages in separate, Use Web site in the long run easier to maintain, and provide a viable alternative to Java ...

Map, Set, List distinction

First: Major categories: 1.Collection: a group of separate elements, that is, its only held every position within an element. List: in order to place elements of placement elements, not to reorder. Set: do not repeat the elements of love then, it will use

One side to the java test questions involved knowledge (1)

To state clearly that the subject is a javaeye job buddy met at the time of a job title, find it fascinating. That brought the discussion, because I found it to be an interviewer particularly like to mention the issue. The problem right: there are tw ...

When I use the FindBugs code of bugs appear

Analysis using findbugs recently did a recent project, found himself writing the code a lot of problems arise, do a little summary here. Here is my code for the bug appears to do a bit of combination of network learning, using Google translation, the tran

Java based IV: Reflection (constructor, member variables, general method, array)

/** * Reflex ( Construction method, member variable , The common method, the array ) * * @author Zhang Xue * */ public class ReflectStudy { @SuppressWarnings("unused") public static void main(String[] args) throws Exception { System.out.println("--------1

Java base 10: JDK dynamic proxy class analysis (java.lang.reflect.Proxy use)

/** * JDK Analysis of dynamic proxy classes (java.lang.reflect.Proxy Use ) * * @author Ming Studies * */ public class ProxyStudy { @SuppressWarnings("unchecked") public static void main(String[] args) throws Exception { // Dynamic proxy classes : General

Based on Struts 2 interceptors to achieve fine-grained role-based access control

Jump to main content China developerWorks> Java technology | Web development | Open source> Based on Struts 2 interceptors to achieve fine-grained role-based access control developerWorks Document layout option will set the printer to print landscap

java object array of Java Array sort sort sort

Java collection object sorting test Java API for sorting the collection offers two types of support: java.util.Collections.sort (java.util.List) java.util.Collections.sort (java.util.List, java.util.Comparator) The first method requires the sort of elemen

struts2 the demo example in the show case of the crud

struts2 the demo example in the show case of the crud [Keywords: struts2, createException, map] Start look the crud example, the actually found that I did not prepare a database of information and data can also be run successfully, then realize until we s

[Reprinted] on the Java Collections API 5 things you do not know, Part 1

Original: On the Java Collections API 5 things you do not know, Part 1 Customization and extension Java Collections Ted Neward , competent, Neward & Associates Ted Neward is Neward & Associ

[Reprinted] Java collection Collection List Set Map difference

Java code package com.suypower.chengyu.collection; import java.util.ArrayList; import java.util.Arrays; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.LinkedHashSet; import java.util.LinkedList; import java

Java Collections API on 5 things you do not know, Part 1

For many Java developers, Java Collections API is a standard Java array and all the shortcomings of a much-needed alternative. Collections main contact will be together with ArrayList not wrong in itself, but for those exploring the spirit of people, this
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