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JAVA basics, strings, and java BasicsString (a character array, constant, unchangeable ): 1. Create and initialize a string: 1). Use a String constant to initialize String s = "hello! "; 2). Create and initialize a String () using the constructor; // Initialize an object, indicating a NULL Character Sequence String (value); // creates a new object using an existing String constant String (char [] value); // create a String using a character array Stri

Java Basics !!!, Java BasicsQuestion 1: What are the results of 0.01 + 0.09? public class MathTest{ public static void main(String[]args){ double a = 0.01, b = 0.09; System.out.print(a+b); }} Why is the printed result 0.09999999999999999 instead of 0.1, and the loss of precision occurs? Both double and float will encounter this problem. Let's talk about float. The 0.1 binary form of float is 00111101110011001100110011001101, the exact value expressed

Python BASICS (3) and python BasicsMy life is short. I want to learn Pyhton. Python is an object-oriented, interpreted computer programming language, invented by Guido van rosum at the end of 1989, the first Public release was released on July 15, 1991. The Python source code also complies with the GPL (GNU General Public License) protocol. The Python syntax is concise and clear, and has rich and powerful class libraries. It is often called the glue

Java (Socket programming basics), socket programming BasicsI,Two main problems in Network Programming One is how to accurately locate one or more hosts on the network, and the other is how to transmit data reliably and efficiently after finding the hosts. In TCP/IP, the IP layer is mainly responsible for locating network hosts and routing data transmission. The IP address can uniquely identify a host on the Internet. The TCP layer provides an applicat

Android BASICS (16) and Android BasicsPull out a little thing Pull out a little thing Introduction Body Additional reading Target Audience: Android beginners without basic knowledge Knowledge Point: Use the support V4 package in Android Studio to implement the pull-down refresh Effect Objective: To implement the pull-down refresh function on the pageIntroduction Support V4 package Import Simple use of the SwipeRefreshLayout clas

HTML + CSS basics and htmlcss BasicsChapter 1I. Style 1. Line Style, Code cannot be maintained, not recommended 2. inline style, not reusable, not recommended 3. External style, reusable, and maintained, recommended Width of Dual-solid lineUse border-width: 4px; Set 2. Direction: border-[top | bottom | left | right] 3. Combination usage: border-top-[width | style | color] 4. border shape:Non-rectangle (inverted triangle, inverted trapezoid ......)4.1

Python BASICS (II): python BasicsVariable Another way to assign values to variables user = 'ljb'passwd = 'ljb123'user,passwd = 'ljb','ljb123' Constant Uppercase variable MYSQL_CONNECTION = '192.168.1.1' Pyc File After the import module, the pyc file is generated in the corresponding directory, and the pyc file is a bytecode file.Python call module ProcessAfter the module is called, The pyc bytecode file will be generated, and the interpreter will exe

is an executable file that runs on a 64-bit platform and uses a dynamic link file (Shared library).7. Edit the fileEditing files under Linux usually we use a dedicated command-line editor like (Emacs,vim,nano), because the content of the editor involved in Linux is more and more important, so we have a separate basic course specifically about one of these editors (VIM). here is a strong hope that you are learning this Linux basic course, you pause here first, to learn the use of the Vim editor

Overview: The composition of JavaScript, the role of each component, One, the composition of JavaScript JavascriptECMAScript (CORE) DOM (Document Object model) BOM (Browser object model) 1.1ECMAScript ECMAScript is a ECMA-262 standardized scripting language that ECMA-262 language: syntax, type, statement, keyword, reserved word, operator, object 1.2 DOM The DOM maps the entire page to a multi-tiered node structure, and each component of the page, HTML or XML, is a type of node that contain

languages such as Java, to make up for the inconvenience of not using global functions and variables in a process-oriented language, allow the declaration of static (static) and static methods in the class. In fact, the objective world does not exist the so-called static concept, because all things are objects! In the prototype object-oriented language, in addition to the built-in object (Build-in object), the existence of global objects, methods or attributes is not allowed, and there is no st

plus 1 for the array. var arr1 = []; ARR1[9] = 1; A length of 10, containing only an array of elements Setting a decimal value deletes the attribute with the property name greater than or equal to length.Setting the length value to 0 is equivalent to emptying the array. var arr2 = [1, 2, 3, 4, 5]; Arr2.length = 3; [1, 2, 3] arr2.length = 0;//[] Array traversal Traversing an array does not use a for in loop to traverse an array, because for-in will traverse all the p

Day 1 Computer basics, day Computer BasicsComputer Basics 1. Why learning computer basics? The role of programming languages: commands that humans use to make machines understand and act. It is similar to English in human society. Relationship: Computer Hardware-Operating System (OS)-software (finished programming language, learning results ). Hardware: There is

Key python notes-basics, python notes-Basics This article aims to refine the basics: A list of knowledge points in the basics 1. print and print "..." Print: print ('Hello World! ') Command Line Mode: Run Python and enter the command in the command line and execute it. Program mode: Write and run a Python program. Not

Android Basics Getting Started tutorial--7.6.1 Socket Learning Network Basics Preparationtags (space delimited): Android Basics Getting Started TutorialIntroduction to this section: To take care of beginners who have not learned Java sockets, or to smooth out the concepts related to network protocols involved in Android development,After all, the intervi

JavaScript language basics 1: javascript language basics We need to know what JavaScript is. First, we need to know what features JavaScript has? What is JavaScript? It is an object-based and secure scripting language! It is a scripting language. Therefore, it has the following features: 1) It is a scripting language and an explanatory language. It is interpreted line by line during the program running. 2

JavaScript language basics 3: javascript language basics JavaScript can process data types from the real world, such as numbers and text. At the same time, JavaScript also contains some Abstract data types, such as object data types. JavaScript is a weak type language. In many cases, when we process data, we do not need to declare the data type. Their types have been calculated. Since JavaScript is a weak t

Parent,intposition) {Toast.maketext ( This, "clicked" + (position + 1) + "item", Toast.length_short). Show (); } @Override Public BooleanOnlongclick (View Parent,intposition) {Toast.maketext ( This, "Long pressed the first" + (position + 1) + "item", Toast.length_short). Show (); return true; }}The rest of the layout file code does not change, rerun the program, and then you can test the click event and the long-voltage event, the effect is as follows:This is a simple way to listen to the 2 Tex

Programming basics 2. java programming Basics [URGENT] C ++ programming basics 2 1.The first is 5000, 714x5 is, and the entire division isThe second is 0, because the operation is 5/7, the result is 0, and then 0*1000 is 0.2.(A B C) |! (A | B | C)Answers to the second edition of object-oriented programming Basics

One of the Microsoft. Net Remoting Tutorials:. Net Remoting basics and remoting Basics I. Remoting Basics What is Remoting? In short, we can regard it as a distributed processing method. From the perspective of Microsoft products, it can be said that Remoting is an upgrade of DCOM, which improves many functions and is well integrated into the. Net platform. Micro

Java basics and java Basics This is a full set of Java knowledge I have prepared in my previous lectures. It is applicable to beginners and intermediate and advanced students. You can download it. I think it is more systematic and comprehensive, it can be up to 90% of the learning materials on the market. I hate the casually written information and the people who sell money! Here I will share it for you for