udacity introduction to programming

Swing was a GUI framework developed by Sun, and at the outset sun was developing the AWT framework. However, the AWT framework has LCD problems. As a result, Sun continued to develop swing on the basis of AWT. Swing is a class that inherits the AWT common components: Text text component Menus menu component Widgets Widget component Top-level-windows Top-level window Management sub-windows child windowOne of the Java GUI programming (swing) is a brief

improve the user experience of graphical software and prevent the "freezing" phenomenon from arising.Risk of threading:The first risk is that the execution sequence cannot be determined under multithreading, and there is an unexpected situation. Using the Java synchronization mechanism can improve the problem.The second risk is the case where a deadlock, such as a program, cannot continue.The third risk is that in multi-threading, thread scheduling and synchronization mechanisms increase resour

[0]=pig[Email protected] ~]# Animal[1]=sheep[[email protected] ~]# echo $animal//reference to "0" elementsPig[[email protected] ~]# echo ${animal[1]}PIG[1][Email protected] ~]#②, assign all elements at once:Format: array_name= ("VALUE1" "VALUE2" "VALUE3" ...) Each element value must be separated by a space keyExample:[[email protected] ~]# weekdays= ("Monday" "Tuesday" "Wedsday")[Email Protected]calhost ~]# echo ${weekdays[2]}Wedsday[Email protected] ~]#③, assigning only specific elements :Forma

， 　　Six. Dedicated underline identifiers 1234567891011121314151617181920212223242526272829 _xxx:不能用frommoduleimport*导入__xxx__:系统定义名字__xxx:类中私有变量下划线对于解释器来说有特殊意义，而且是内建标识符所使用符号，不建议自定义变量以下划线开头但是如果是类中的私有变量，__xxx将会是一个好习惯系统变量__name__会根据python文件被加载方式的不同得出不同的值。 　　　　python文件被当作模块导入：__name__=模块名或者文件名　　　　python文件被执行:__name__=‘__main__‘在我们使用python编写一个软件时，应该只有一个主程序中包含大量顶级代码（就是没有缩进的代码，python解释器读取到顶级代码会立即执行），其他.py文件应该只有少量顶级代码，所有功能都应该封装在函数或类中。通常在文件结尾结合__name__变量，编写测试代码 。 　　Sev

' Marks: '%d ' '% SE Lf.markst = Teacher (' Mrs. ShriVidya ', Max, 30000) s = Student (' Swaroop ', ', ') Print # prints a blank linemembers = [T, s]for member in Members:membe R.tell () # Works for both Teachers and Students$ python inherit.py(Initialized SchoolMember: Mrs. Shrividya)(Initialized Teacher: Mrs. Shrividya)(Initialized SchoolMember: Swaroop)(Initialized Student: Swaroop)Name:"Mrs. Shrividya" Age:"40" Salary: "30000"Name:"Swaroop" Age:"22" Marks: "75"Python does not automatically

Introduction to MapReduce and HDFsWhat is Hadoop? Google proposes a programming model for its business needs MapReduce and Distributed file systems Google File system, and publishes relevant papers (available on Google Research's web site: GFS, MapReduce). Doug Cutting and Mike Cafarella the two papers when they developed the search engine Nutch, the MapReduce and HDFs of the same name, together with Hadoo

Brief introduction In a multiprocessor architecture for shared memory, you can use threads to implement parallelism. For Unix systems, the IEEE POSIX 1003.1c Standard prescribes the standard for the C language Threading programming interface. The implementation of this standard is POSIX threads, or called pthreads. This article begins by introducing the basic concepts of threading, motivation, and design

Introduction to MVC Programming using Agavi, part 2nd: Adding Forms and database support using Agavi and Doctrine 2 Get Database records Now that communication between Agavi, doctrine and MySQL is clear, you need to write a viewaction to get and display the list of cars from the MySQL database. First, populate the listing table with some sample records, which is handy for testing during the initial develo

table1;Execute SQL ScriptSource My.sql--my.sql-------------------Insert INTO table1 (name, sex, Age, Class) VALUES (' Xiao Wang ', ' Female ', ' C + + class '); insert into table1 (name, sex, Age, Class) VALUE S (' Xiao Li ', ' Male ', ' C + + class '), insert into table1 (name, sex, Age, Class) VALUES (' Xiao Zhang ', ' Male ', ', ' Java class '); insert into table1 (n Ame, sex, age, Class) VALUES (' pock ', ' female ', ' C + + class '), INSERT into table1 (name, sex, age, Class) values (' Zha

user(B) thzzc1994(C) Null valueAs already mentioned, the variable value of sh, the parent shell is not get. So this question can be regarded as only one sentence, that is[Email protected] ~]# echo $userThe result is, of course, a null value.Conclusion: (1) The child shell script inherits the parent shell's variables, functions and so on, as if the son follows the father's surname, the gene inherits the father's, and vice versa.(2) If you want the parent shell to inherit the child shell, use the

substitute for shell scripts. The script is a process framework, and the actual work is still completed in fortran. I write a script on windows and finally run it on linux. I should pay attention to the path issue. Introduction to the historical development of the Python Programming Language Introduction to the implementation of the Python

version of Fpjs will be listed in August, then save to eat English. By the way, "functional JavaScript" Chinese version named "JavaScript Functional Programming", people originally the title is very concise, translated into "functional Javascript" not? No "programming" two words afraid no one knows this is a programming material? This makes Fpjs love. No way, I

JavaScript: Introduction to Object-Oriented ProgrammingIntroduction In this article, we will consider various aspects of object-oriented programming in ECMAScript (although this topic has been discussed in many previous articles ). We will look at these problems more theoretically. In particular, we will consider the object creation algorithm and the relationship between objects (including basic relationshi

simpler design than Perl, this makes Python more readable, easier to maintain, and helps reduce program bugs. Simpler and easier to use than Java, Python is a scripting language, and Java inherits a lot of syntax and complexity from system-wide languages like C + + Simpler and easier to use than C + +, but usually does not compete with C + +, because Python, as a scripting language, often plays many different roles. More powerful and cross-platform than Visual Basic, because Python is ope

Document directory Introduction to hundred-class Delphi7 Programming Introduction to hundred-class Delphi7 Programming DelphiTutorial Series of books(073)Hundreds of classroomsDelphi7Programming Basics Organize netizens (state)Email:Shuaihj@163.com : PDF Title: Hundred-class courses:

solution of the problem, rather than the "definite" optimal solution, because there may be multiple solutions to the optimal value.In order to save time for repeating the same sub-problem, the introduction of an array, whether or not they are useful for the final solution, saves all sub-problems in the array, which is the basic method used in dynamic programming.Ii. General steps for solving dynamic programmingThe design of the dynamic

The introduction to Programming (Java) Plato the principles of Law, Liskov and Parnas as the three cornerstones of the object-oriented programming paradigm.The first principle of object-oriented paradigm, yqj2065 called Plato's Law, is the source of conceptual paradigm and psychological paradigm of object technology, and object technology simulates the real world

programming .See AlsoThird, seeThe content in this document applies to Xcode 4.4 or later and assumes is targeting either OS X v10.7 or later, or IO S 5 or later. For more information on Xcode, see Xcode overview. For information in language feature availability, see objective-c feature availability Index.Objective-c apps use reference counting to determine the lifetime of objects. For the more part, the Automatic Reference counting (ARC) feature of

get a runtime error called an EX Ception.Downcasting and the runtime checks require extra time for the running program and extra effort from the programmer.The solution is called a parameterized type mechanism. (Java se5,called generics)A parameterized type (compiler-level technology) is a class, the compiler can automatically customize to work with particular Types.Object Creation LifetimeWhen to destroy object?C + + takes the approach that control of efficiency are the most important issue,

I believe many people are interested in network programming. Next we will introduce it in network programming.Winsock API, the most widely used programming interface. To use Winsock API programming, You should know some basic knowledge about TCP/IP.You can directly use the Winsock API to write network applications. However, you must write excellent networkThe app