aws fundamentals

StringBuffer =NewStringBuffer (text); - System.out.print (Stringbuffer.reverse ()); the } - -}The results of the operation are as follows:3. Convert a string to byte[], byte[] is to store each character of the string as a byte type, but not a char type. So there is no direct reverse output (not like 1). However, we can convert the string to byte[] , and then we can exchange the elements in the end of the symmetry, so that the reverse output is achieved:1 Packagehimi.hebao05;2 3 Publi

{ -System.out.print (""); + } A } at System.out.println (); - } - /*print the lower half of a diamond triangle the middle row is common so the number of rows is Length-1*/ - for(inti = length-1; i > 0; i--) { - for(intj = 1; J ) { -System.out.print (""); in } - for(intK = 1; K ) { to if(k = = 1 | | k = = 2 * i-1) { +System.out.print ("*"); -}Else { theSystem.out.print (""); *

//System.out.println (Rt.freememory ()); System.out.println (Rt.totalmemory ()); try { //process java.lang.Runtime.exec (String command) //execute an external program as a sub-process //rt.exec ("notepad") of the current program; You can also use exec to compile the source files for Java. rt.exec ("Javac Hello.java"); Process p = rt.exec ("java Hello"); InputStream is = P.getinputstream ();//Get in

1. Create1) can be created by assigning values2) can be created by floating-point string3. By using fractions, it is possible to perform certain values accurately, rather than due to the accuracy of floating-point numbers, resulting in differencesRight here, thank you.------------------------------------------------------------------Click to jump 0 basic python-CatalogueCopyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.0

both ends of the communication.* Network communication is actually the communication between sockets.* Data is transmitted via IO between two sockets.* *//** Network Programming:*1 Network Model:*OSI Reference Model:*TCP/IP Reference Model:* 2. Network communication elements:* IP Address:* Port number:*Transport protocol:*3. Define the communication rules:*Language is different, communication needs rules, this rule is called protocol.*The international organization defines the universal protoco

the class and function are, making it clearer' guessnum.py--guess number game ' Import Randomimport time# build the game's core gameplay class core (object): ' Core--core class ' version=1.0 def guessnum (self): ' Guessnum--guess digital Core method ' Try:secret=random.randint (1,100) #生成随机数 #print (Secret) time=6# guess number of times guess=0# input number minnum=0# minimum random number maxnum=100# max random number print (" ---------Welcome to the place where you g

elements is sufficient, but the program sometimes needs to process 200 elements. For security purposes, an array containing 200 elements is used. In this way, the program wastes memory in most cases. OOP makes the program more flexible by deferring such decisions to the run stage. After the program runs, you can tell it requires only 20 elements, and you can tell it requires 205 elements next time.In summary, when using OOP, the programmer may determine the length of the array at run time. To u

1. Truth test* Any non-0 numeric or non-empty objects are true* Number 0, empty object, and special object none are all fake.* Comparisons and equivalence tests are recursively applied to data structures* Comparison and equality tests will return TRUE or False* Boolean and and OR operators return TRUE or false operandsX and Y: if x and Y are true, it is trueX or Y: if x or Y is true, it is trueNot x: If x is false, it is trueAbove are some special examples:Because empty lists, tuples, and dictio

enter the number is:", guess) if Guess==secret: print ("guessed right, really bad") else: # When not equal, you also need to print out the corresponding interval, making it easier for users to use if GuessThis time the game is quite perfect, but it can only provide a user to play, we will introduce the next lesson to the listSo as to realize the function of multi-user guessing.This is the section here, thank you.--------------------------------------------------------

Back to our game today, we add conditional judgment statements to our game and enrich gameplayOur previous code:Print ("---------Welcome to the place to guess the numbers, start---------") #输出提示guess =int (Input ("* Number range 0-100, enter the number you guessed:")) #读取输入, and then assign print (guess) # Print inputThe above is our previous code, relatively simple, just print the number you entered, forget it.We're in there today to add conditional judgments that make the game rich dot1. First

class. For objects associated with soft references, only when the memory is lowThe JVM will not recycle the object. Therefore, this is a good way to solve the problem of oom, and this feature is well suited for caching: such as Web caching, image caching, and so on. 3). Weak references (WeakReference): Weak references are also used to describe non-required objects, and when the JVM is garbage collected, the objects associated with the weak references are reclaimed, regardless of sufficient mem

occurs. - Private Static Final LongSerialversionuid = 1L; + PrivateString name; A Private intAge ; at //static members belong to a class and cannot be serialized. - Private Static intcount; - //transients cannot be serialized either. - transient Private intkey; - - Person () { inSYSTEM.OUT.PRINTLN ("Null parameter constructor"); - } to PublicPerson (String name,intAge ) { +System.out.println ("Parametric constructor"); - This. Name =name; the

derives from C + +, but omits all the incomprehensible features in C + +, such as header files, pointers, structures, cells, operator overloads, virtual base classes, and so on.portability: written programs can be run without modification on Windows, MacOS, UNIX and other platforms to "write once, run everywhere."Object-oriented: Java is a fully object-oriented language.Explanatory: Java interprets Java code by running the Java interpreter on different platforms (Java has a corresponding interp

Len (s) Request length "A%s parrot"% kind String formatting expressions "A {0} parrot". Format (Kind) Method of String formatting S.find (' xxx ') Search S.rstrip () Remove spaces S.replace (' xxx ', ' xxx ') Replace S.endswith (' xxx ') End With XXX ' xxx '. Join (Strlist) Entry and exit separators S.encode (' latin-1 ') Chan

Static memory allocation and dynamic memory allocation in C + +:1. The static object is a variable with a name, we manipulate it directly, and the dynamic object is a variable with no NameWe manipulate it indirectly through pointers. (Static memory allocation is because when the source code is compiled, the compiler allocates memory space for the variable instead of allocating memory when the program executes, and dynamic memory allocation allocates memory when the program executes).2. The alloc

1. Statements are executed on a line-by-row basis, unless you do not writeIf the statement uses an if statement, his execution is jumping, and the IF statement is the process control2. Automatic boundary detection of blocks and statementsBecause Python does not have curly braces for these bounding symbols, it uses code indentation to control boundariesSimilarly, the end of a statement is not using semicolons, but also using code indentationIn the above example, for the indentation before the for

Object-oriented three features: encapsulation, inheritance, polymorphismThis section is the embodiment of object-oriented polymorphism1. Upward transformation of objectsThe upward transformation----assigns the object of the subclass to a reference to the parent class;Student s = new Student ();Person p = s;Or it can be writtenPerson p = new Student ();What members (variables and functions) can be called by a reference, depending on the data type of the applicationWhich method a reference invokes

(parameter) calls the constructor of the parent class ..... Ibid.Replication is also known as overwriting or rewriting1. Among the two classes that have a parent-child relationship2. The parent class and subclass each have a function, the definitions of the two functions (return value type, function name and parameter list) are identical5. Use super to call member functions in the parent classOverloading is in a class, the replication is in two classes, with Super call the parent class function

Reflection is of great significance in Java and is a dynamic mechanism for loading, detecting, and using classes that are completely unknown during compilation. In other words, a Java program can load a runtime to know the name of the class, learn its full construct (but not including the methods specific definition), and generate its object entities, or set values on its fields, or use its methods. Reflection is the basis of the framework, and the framework can greatly save the development cost

all the data in a curly brace, assigning an initial value to each element in the order in which the array is arranged.int a[3][4]={0,1,2,3,4,5,6,7,8,9,10,11};③ only assigns initial values to some elements.int a[3][4]={{1},{2},{4}};1 0 0 02 0 0 04 0 0 0int a[3][4]={{1},{0,2},{0,0,4}};1 0 0 00 2 0 00 0 4 0int a[3][4]={{1},{3,2}};1 0 0 03 2 0 00 0 0 0int a[3][4]={{1},{},{9}};1 0 0 00 0 0 09 0 0 0④ If an initial value is assigned to all elements, the first-dimension length can be unspecified when t