j2se

J2SE quick advanced -- four basic abstract classes of IO stream: InputStream, OutputStream, Reader, Writer, and abstract class The above section briefly describes the four abstract classes in the java. io package and Their Relationships. Here we will further summarize them and their subclasses. At the end of the previous blog, I posted the entire IO family in Java, and then I modified it again. On the basis of this, I identified the node stream and p

[Video] beginner course-operators-Java J2se,-javaj2se This section mainly describes the application of operators. Java operators include: Arithmetic Operators Value assignment operator Logical operators Bitwise operators Ternary Operators Here we have recorded videos to explain these operators and provided you with exercises. Interview Questions: 1. What is the most efficient way to calculate the value of 2 multiplied by 8? 2. Swap the values of T

J2SE basics: 3. Create and use a class namespace and access permission for an object1: package. A package is a class container used to save the namespace of a category. Logically, classes are divided. Resolves conflicts between classes with the same name. 2: package naming rules: A: The package must be written in the first line of the source file. B: All package names must be in lower case. C: (recommended) package uses the compan

Use J2SE API to read Properties files1. Use the load () method of java. util. Properties classExample: InputStream in = lnew BufferedInputStream (new FileInputStream (name ));Properties p = new Properties ();P. load (in );2. Use the getBundle () method of the java. util. ResourceBundle classExample: ResourceBundle rb = ResourceBundle. getBundle (name, Locale. getDefault ());3. Use the constructor of the java. util. PropertyResourceBundle classExample:

In the course of learning Java, it is very important to master the basic concepts of Java. J2SE is the basis of Java, therefore, it is necessary to summarize the basic concepts so that you can better understand the essence of java in the future. I have summarized 30 Basic concepts here.Java Overview:Currently, Java is mainly used in middleware development (middleware)-to process communication technologies between clients and servers. Early practices h

provide a way to access the machine-independent Java primitive type data.Import java.io.*;p ublic class testdatastream{public static void Main (string[] args) {Bytearrayoutputstream baos=new Bytearrayoutputstream ();//This class implements an output stream in which the data is written to a byte array//Creates a new data output stream and writes the data to the specified underlying output stream. DataOutputStream dos=new DataOutputStream (BAOs); Try{dos.writedouble (Math.random ());d Os.writeboo

The inheritance relationships of common data structure objects in 1.j2se such asCollection........| --------List........| ..........| ----------ArrayList........| ..........| ----------Vector........| ..........| .............| -----Stack........| ..........| ----------LinkedList........| --------Set...................| ----------HashSet....................| .............| -----Linkedhashset...................| ----------SortedSet.....................

Recently, everyone is talking about containers and how to actually apply it in the project, because there is no concept of the container, so the j2se inside the container to see some basic knowledge, summed up the most basic things.The core of the whole chapter belongs to the following picture.I. Conceptual understandingWhy should have a container this concept: just contact, in my understanding: in programming, often encounter with duplicate functions

parameters: Arguments to functions when declaring a function. Arguments: Parameters that are passed to the function when the function is called. Ii. The origins of these concepts: Why use variables? Better deal with a class of data rather than a single data. If there are no variables, you can only operate on individual data. Why are data types introduced? 1. The operation of the variable is more convenient and reduces the error rate.

One step to learn the implementation principle of J2SE-HashMap,HashMap Data Structure The data structure of HashMap is implemented through the array and linked list. Arrays are the subject of HashMap, and linked lists are used to solve the Hash collision problem. 　　 HashMap Of Put Method 1. When put, first judge whether the key value is null. If it is null, the null value is the location where the key is placed. 2. If the key value is not null, hash i

J2SE advanced-Java memory Analysis Program Execution Process To analyze the memory in Java, let's first take a look at the program execution process: As shown in, there are roughly three steps: 1. At the beginning, our program exists in the hard disk. When it is started and running, the program will be loaded into the memory. The memory here can be seen as our memory; 2. At this time, in addition to the code of the newly loaded program, the code

Java basics-something about J2SE-general Linux technology-Linux programming and kernel information. For more information, see the following. In java, the development interface is annoying. Pay attention to the following issues: 1. Jframe cannot be placed in JPanel, which is different from iframe in html. 2. the dialog in java is not completely controlled, except for the default prompt dialog boxes. 3. If the layout needs to be free, select null and

add a lock on each method.The above is related to the thread involved in the knowledge, for the soft test, only need to understand the thread and the basic concept of the process, the specific code can not be in-depth understanding. In addition, about the operating system related to other knowledge, you can refer to the introduction of the operating system, which also involves disk reading and writing, file read and write, PV operation, the mechanism (producer and consumer issues)

This section mainly explains the application of operatorsThe Java operators are divided into:Arithmetic operatorsAssignment operatorslogical operatorsBitwise operatorsTernary operatorsHere is a video to explain the major types of operators, and there are exercises to provide everyoneInterview questions:1. The most efficient way to figure out 2 times 8 equals a few?2. Swap the values of two integer variables (no third-party variables required)The answer is in the website forum-the third lesson af

Build path Specifies execution Environment j2se-1.5. There are no JREs installed in the workspace of that are strictly and this compatible. Manually load the JRE system library in Java build path. Can be solved on a temporary basis. However, once the Maven-update project configuration is executed, the configuration is restored and the warning appears, so Changing the pom file is kingly

Autoboxing and auto-unboxing of J2SE primitive types We know that in Java, the native type such as Int,long is not a class that inherits from object, so there are many operations that we cannot use primitive type operations, such as trying to put an integer into a set, we must first create an integer object, The object is then put into the collection. When we take the number from the collection, we take out an integer object, so we can't use subtracti

j2se| static static introduction (static Import) In the past we were going to use static variables from a class in another package, usually preceded by the corresponding class name: Double r = Math.Cos (Math.PI * theta); With static introduction, we can remove the previous class name, and the static introduction of the statement is this: Import static Java.lang.Math.PI; It must be noted that this is not the end of class math, but direc

j2se| inheritance The results of the operation prove that this method is correct. Here we use the Writeobject/readobject method, which, if it exists, is invoked when serialized, in place of the default behavior (which is discussed later, so much more). When we serialize, we first invoke the ObjectOutputStream Defaultwriteobject, which uses the default serialization behavior and then serializes the domain of the parent class, as well as when deserializ

IP address |j2se How to use Java to obtain the IP address of a domain name? The class that provides this functionality is called java.net.InetAddress. Let's assume that there is a domain name that uses a static getbyname to regain a inetaddress and then get an IP address that can be read out. The following code is a very basic command line. Import java.net.InetAddress; Import java.net.UnknownHostException; public class NsLookup { static public void M

As the name implies, variable length parameters refer to any number of parameters in the parameter body of a method. They are similar to object arrays. In J2SE 5.0, a new syntax is introduced, that is, adding... after the parameter type name indicates that this method can accept multiple parameters of this type. It must be noted that the variable length parameter must be placed at the end of the parameter list, and a method can only contain one such p