Java

1. Vector- specific features :(1) Add functionpublic void addelement (Object obj)--add ()(2) Get functionPublic Object elementat (int index)--get ()Public enumeration elements ()--iterator Iterator ()Enumeration (Interface):Boolean hasmoreelements ()

The system first installed the jdk1.8, the environment variable is configured Jdk1.8,java-version and javac-version version of the same.Then installed the jdk1.7, the environment variable java_home changed to 1.7, but the cmd input java-version and

Threadlocal Source Code AnalysisThreadlocal is actually quite simple, because there are three public methods in the class: set (T value), get (), remove (). The first analysis of the source clearly know threadlocal is what to use, reuse, the final

The three main characteristics of object-oriented: encapsulation, inheritance and polymorphism. Polymorphism is an important mechanism for code reuse in programming, which indicates that there are different semantics when the same operation works on

1. Reflection of the application scenarioI. OverviewReflective technology:Java reflection mechanism is in the running state, for any class, can know all the properties and methods of this class, for any one object, can call any of its methods and

(1) The element to be put into HashMap is key-value.(2) The bottom is the hash structure that the previous data structure course talked about.(3) To put elements into the hashmap, then the type of key must implement the implementation of the

We know that the Java language provides 4 types of references: Strong references, soft references (softreference), weak references (WeakReference), and Ghost References (Phantomreference), which are closely related to references, There is also a

1. Case:Determine if there is a file with a suffix of. jpg under the F-disk, and if so, output the file name.2. The case code is as follows:(1) The idea is: First get all the files and folders encapsulated objects, and then traverse the time, in

Character Stream Filereaderfilewriter Bufferedreaderbufferedwriter Outputstreamwriterinputstreamreader BYTE stream fileinputstreamfileoutputstream bufferedinputstreambufferedoutputstream system input: InputStream in =System.in;O Utputstream out =

1. Exception Precautions:(1) When a subclass overrides a parent class method, the child class's method must throw the same exception or subclass of the parent exception . (father is broken, son can not be worse than father)(2) If the parent throws

Using the graphics class to draw any explicit function image, just modify the F () function in the code, and adjust the Timesx and Timesy parameters to zoom in or out of the image in the direction. You need to redefine the coordinate system.1

Java was originally introduced as a network programming language, which provides a high degree of support to the network, which makes the communication between client and server become reality, and in network programming, the socket is the most used.

Command-line arguments are strings, which must be converted to numbers before they can be added. The following is the flowchart, source code and output results.Flow chart:Source:Import Java.util.Scanner;public class Test {public static void Main

1 //The parseint method and the character.digit are not allowed when the numeric string is converted to a numeric type (the legitimacy of the input string is not considered here)2 Public classConvertnumstr {3 Public Static voidMain (string[]

1. What is ArrayListArrayList is a dynamic array legend, using the MSDN statement. That is, the array complex version number, which has the following advantages, such as: Dynamic addition and lowering of elements Implements the

DirectoryJava EE: First, illustrated HTTP protocolJava EE: Second, graphic Cookie (cookies)Java EE: Three, graphical session (sessions)OverviewFirst, technical Cornerstone and OverviewIi. in-depth understanding of technical cornerstones and

There is no space, connection number, or bottom line link between the words (for example, Camel case, camel-case, or camel_case form). There are two kinds of formats: 1, Small Hump-type nomenclature (lower camel case): The first word starts with a

To be a good Java programmer, it is essential to have a good code-writing habit. Let's take a look at 30 suggestions for code writing.(1) The first letter of the class name should be capitalized. The first letter of the field, method, and object

First, using the Scanner class for console inputThe scanner class in the document is defined as a simple text scanner which can parse primitive types and strings using regular expressions (one can use regular expressions to parse the base Simple

Since most of the company's projects now use the combination of client and service as a complete project, the communication between client and service is using spring invoke, which causes the Pojo and service interfaces to be redundant in two