Java learning notes -- iterator and java learning notes --To achieve uniform traversal of different types of containers, an iterator is used. It mainly uses two interfaces: Iterator and Iterable. The class that implements the Iterable interface indicates that this class can be traversed using the iterator, such as List and Set.Target class to be traversed. The class that implements the Iterator interface in
Java basic knowledge learning notes (1), java learning notes
Understanding object-oriented:
Java's pure object-oriented programming language is represented by three basic features fully supported by Java: inheritance, encapsulation, and polymorphism.
The minimum unit of a Java program isClassClass represents a type of thing with certain characteristics in the objective world. These classes can generate mult
C ++ Primer Reading Notes (1) Article 1: C ++ overview, Chapter 1: Start, primer Reading Notes
1. Main Content
This article introduces the core idea of programming language and basic concepts of C ++.
What impressed me a lot isDivide and conque)Decomposition idea.
2. Knowledge Square
1) C ++ file suffix
Cc, cpp, and cxx
2) compiler Functions
1. Check errors (syntax errors and type errors );
Linear regression learning notes and regression learning notes
Operating System: CentOS7.3.1611 _ x64
Python version: 2.7.5
Sklearn version: 0.18.2
Tensorflow version: 1.2.1
Linear regression is a statistical analysis method that uses regression analysis in mathematical statistics to determine the quantitative relationship between two or more variables. It is widely used. The expression is y = w'x + e, and
Learning notes TF028: simple convolution network and learning notes tf028 convolution
Load the MNIST dataset. Create the default Interactive Session.
The initialization function creates random noise to break the complete symmetry. Truncates Normal Distribution noise, with a standard deviation of 0.1. ReLU, offset plus a small positive value (0.1) to avoid dead nodes (dead neurons ).
Convolution function, tf
DX notes --- Direct3D basics, dx notes --- direct3d
I. Prerequisites
1. Surface
The surface is a pixel matrix used by Direct3D to store 2D image data. Width and height are measured in pixels, and pitch is measured in bytes. The interface IDirect3DSurface is used to describe the surface.
LockRect: This method is used to obtain the pointer pointing to the surface storage area. You can perform read/write op
Java learning notes 43 (brief introduction to the print stream and IO stream tools) and learning notes
Print stream:
There are two classes: PrintStream and PrintWriter. The methods of the two classes are the same. The difference is that the constructor
PrintStream: constructor: receives the File type, receives the string File name, and receives the byte output stream (OutputStream)
PringWriter: constructor:
JAVA Study Notes (3) and java Study Notes
@ SuppressWarnings ("resource") is used to suppress resource leakage warnings. For example, if I/O class is used, it is not closed.Set features:1) unordered, not random2) unique element3) No subscriptNote: Collection List Set is an interfaceNote: Because the Set does not have a subscript, the value of for cannot be used, and only the iterator can be used.HashSet: th
PHP Reading Notes operator explanation, Reading Notes operator explanation
What is an operator?
What is an operator? An operator is an identifier that tells PHP to perform related operations. For example, if you want to calculate the value equal to 123 multiplied by 456, you need a symbol to tell the server that you need to perform a multiplication operation.
What are the operators in PHP? PHP operators inc
Yii2 source code learning notes (17th) and yii2 source code learning notes
Theme class: the topic of the application. You can use the replacement path to get the root path and root link: yii2 \ base \ Theme. php.
1
PHP learning notes: Use php to read xml files and take notes in xml
Xml has been gradually replaced by json. Currently, APIs are all using json, but some old websites still use xml.
Here, the default xml file is address. xml, which is stored in the same directory as the read PHP file. The xml content is as follows:
Xml reading Method 1:
Xml reading Method 2:
PHP Cookie learning notes and phpcookie learning notes
What is Cookie?
Cookie is a mechanism for storing data on a remote browser and tracking and identifying users. Simply put, Cookie is a text file temporarily stored on the user's hard disk by the Web server and subsequently read by the Web browser. When a user accesses the Web site again, the website reads the Cookies file to record the specific informat
C ++ Study Notes 1 (extended: Format control in C ++), extended learning notes
In the previous chapter, we learned about the standard input and output problems in C ++, so some people may ask questions. In the C language, we can flexibly control the output and display, can I implement it in C ++? My answer is certainly yes, but the control in C ++ may be a little more complicated than that in C ++, then let
C ++ study notes 44: inheritance and derivation, study notes 44
Class combination, class inheritance
Class combination (automobile, wheel, now you can combine the wheel class into the automobile class ;)
Class inheritance (transportation tools and automobiles. At this time, automobiles can be derived from transportation tools ;)
Combination: Common descriptions of has ..
Inheritance: common description is .
Dapper Study Notes (2)-link reference, dapper Study Notes
When studying the Dapper source code, we found SqlMapper In the Dapper NET45 class library. there is a blue arrow icon in front of the cs file and it is found that SqlMapper does not exist in the Dapper NET45 folder. cs file. The complete path in its file attribute points to SqlMapper In the Dapper NET40 folder. cs files, such:
It is found that i
Method overloading of Java learning notes, dynamic method scheduling and abstract classes, and java learning notes
I. Method Overloading
If the method in the subclass has the same method name as the method in its superclass, it is called the method in the subclass to overload the methods in the superclass, especially when the method names and parameter types in the superclass and subclasses are the same, wh
Java for Reading Notes, java for Reading Notes
Expression puzzles
"Odd
When the remainder operation is performed, a non-zero result is returned. It has the same positive and negative symbols as the left operand.
Zero puzzles
Avoid using float and double where exact answers are needed. For currency operations. Use int, long, or BigDEcimal.
Long division
When you are building a large number, you must never l
Notes for problem finding and function implementation, and notes for finding implementation
Before writing this article, I hesitated for a long time to write questions about the application of arrays and collections, and analyzed the difficulties. However, I thought that the current array and set are only simple applications, and the problems I encountered are only caused by poor basic knowledge and poor
Thinkphp learning notes: Table queries and thinkphp learning notes
During the operation, the two table queries are normal, but the three table queries start to cause problems.
There are three tables, including the pl table (uid, content), user table (id, username), and lyb table (uid, title)
You can use the following methods to query multiple tables:
(I) view model (recommended)
Define the view Model. You o
Data science Study Notes 1. science Study Notes
Mutiple Plots on One Graphplt.plot(x, norm.pdf(x))plt.plot(x, norm.pdf(x, 1.0, 0.2)) #1.0 = mean, 0.2 = DSplt.show()
Use plt. savefig to save the image as blank:
Solution: Call plt. savefig before plt. show ().
Scatter Plot
From pylab import randnX = randn (10000) Y = randn (10000) plt. scatter (X, Y) # Pay Attention to the sequence. Draw a picture first and t
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