how to practice coding in java

Package Com.text_1;public class Cat { //write Java applications as required. (1) Create a class named Cat://Properties: Name, fur color, age//behavior: Display name, Yell//(2) Write main class://Create an object cat, named "Nicole", Hair color is "gray", age is 2 years old, the screen to lose//out of the object's hair color and age, Let the object call the display name and shout two methods. String Name,color;int age;cat (string name,strin

Package Com.text_1;public class Student {//write Java applications. First, define the class--student that describe the student, including attributes such as study number (int),//Name (String), age (int), and two methods: Student (int stuno,string name,int)//For initializing an object, Output () is used for outputting student information. Next, define a main class--//testclass, create multiple objects of the student class in the main method, use these

the method that specifies the file that the Formtemplateid points to3 */4 PublicString Downloadformtemplatebyid ()throwsexception{5HttpServletRequest request=servletactioncontext.getrequest ();6HttpServletResponse response=servletactioncontext.getresponse ();7String formtemplateid=request.getparameter ("Formtemplateid");8Formtemplate formtemplate=Formtemplateservice.getformtemplatebyid (Formtemplateid);9File file=NewFile (Formtemplate.geturl ());TenString Filename=urlencoder.encode (F

Java Theory and Practice: Correct Use of Volatile variables (1) The volatile variable in Java can be seen as a "to a lesser extent"synchronized"; AndsynchronizedCompared with the block, the volatile variable requires less encoding and less runtime overhead. However, the only function it can implement issynchronized. This article introduces several effective mod

This is my note on the Java course of learning web. The original video link is: http://www.imooc.com/learn/855-1 Basic NotationSelf-complementary shortcut keys: ALT +/5-2 input and outputUse the Scanner tool class to get user-entered score informationThe scanner class is located in the Java.util package and needs to be imported when using the packagesteps:1. Import Java.util.Scanner2. Create a Scanner object3. Receive and save user-entered valuesdiffe

1. The string is not the first of 8 basic data types, string is an object.Because the default value of the object is NULL, the default value of string is also null, but it is a special object that has some features that other objects do not have.2. New string () and new String ("") are all declarations of a new empty string, that is, the empty string is not null;3. String str= "Kvill";String Str=new string ("Kvill"), the difference:Here, we don't talk about heaps, or stacks, simply introduce the

return 0; the}G. Flood problemsTime limit: C/s 1 sec, other languages 2 secondsSpace limitations: C/C + + 32768K, other languages 65536K64bit IO Format:%lldLinks: Https://www.nowcoder.com/acm/contest/75/GSource: Cow Network topic Description Give a number n, ask 1 to N, how many number is not a multiple of 2 5 11 13. Input Description:There are multiple sets of inputsOne number per line n,1Output Description:The output output of each row is not a multiple of 2 5 11 13.Example 1 input15Outpu

(); } PublicItem Next () {if(!hasnext ())Throw Newnosuchelementexception (); Item Item=Current.item; Current=Current.next; returnitem; } } //Check internal invariants Private BooleanCheck () {//check a few properties of instance variable ' first ' if(N ) { return false; } if(n = = 0) { if(First! =NULL)return false; } Else if(n = = 1) { if(First = =NULL)return false; if(First.next! =NULL)return false; } Else {

table obtains some not the rule law: is not the law of Law:ON the cusp, you can change the condition. Let the condition change with the outer loop. With a pointed face, you can initialize the value so that the initialization changes with the outer loop. 4, Print diamond (◇) or pyramid/* ----* ---* * --* * * -* * * * * * * * * * * * * * -* * * * --* * * ---* * ----* */ Copy Code code as follows: Class ForForTest2 { public static void Main (string[] args) { for (int x=0;

relationship. What about using the map collection? When there is a mapping between the data, you need to think of the map collection first. Idea: 1, converts a string into a character array. Because you want to operate on every single letter. 2, define a map collection, because the letters of the printed results are in order, so use the TreeMap collection. 3. Iterate through the character array. Use each letter as a key to check the map collection. If NULL is returned, the letter and 1 are stor

Volatile variables in the Java language can be thought of as "light", and synchronized synchronized volatile variables require less coding and run-time overhead than blocks, but only part of the functionality that they can implement synchronized . This article describes several patterns for using volatile variables effectively, and highlights several scenarios where volatile variables are not appropriate. The lock provides two main features: Mutual ex

Write multi-threaded applications that simulate multiple people through a cave:1, this cave can only pass one person each time, each person passes through the cave for 5 seconds 2, randomly generated 10 people, at the same time to prepare the cave, showing the name of each person through the cave Muthreadtest.java Packagecom. Train; Public classmuthreadtest{ Public Static voidMain (string[] args) {//TODO auto-generated Method Stub//Create a caveTunnel Tul =NewTunnel (); //10 people across the

-based method or temporal table method, you should first look for a set-based solution to solve the problem, and the set-based approach is generally more efficient.22. Try to avoid large transaction operation and improve the system concurrency ability.23. Try to avoid the return of large data to the client, if the amount of data is too large, should consider whether the corresponding demand is reasonable.By doing Itoo from V1.0 To V3.0, plus the previous project, in fact, when doing SQL optimiza

1220Conversion of arbitrary binary numbers (2-62) to each otherThe method is converted into 10 and then converted into the desired system by taking the remainder method.CodeImport Java.util.*;import java.math.*;p ublic class main{public static void Main (string[] args) {Scanner in=new Scanner ( system.in); int n=in.nextint (); while (n-->0) {int a,b;a=in.nextint (); B=in.nextint (); String Str=in.next (); BigInteger big=biginteger.zero;int k=0;for (int i=str.length () -1;i>=0;i--) {if (Str.char

How to construct the parent and child classes:If there is a default parameterless constructor in the parent class, calls are made automatically in the constructor of the child class. If the parent class has its own constructor, and the parent does not have a default parameterless constructor, then in the constructor of the subclass, you must call a constructor of the parent class, and it must be called in the first statement of the constructed method, in the form super () If placed in another pl

[Java concurrent programming practice] -- "J. U. C": Condition, j. u. ccondition Before reading Condition, let's take a look at the following example: Factory type, used to store and retrieve goods: Public class Depot {private int depotSize; // repository size private Lock lock; // exclusive lock public Depot () {depotSize = 0; Lock = new ReentrantLock ();} /*** warehouse receiving ** @ param value */public

in the use of this tool can be a smooth transition, and nginx this software, for the vast number of developers just meet these two requirements, without heart, users will appreciate, intentions, is to let users do not understand, inseparable from! Isn't that the thinking of Internet products? Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced. The above describes the Java cluster optimization-

the target character array.4, String.Replace () replaces the element or substring in the original string. Returns the replaced string.5. String.touppercase () capitalizes the characters in string strings.6, String.tolowercase () to lowercase characters in string strings.7, String.Trim () remove the string header space.8, String.tochararray () converts a string to a character array.Four, string encryption.First, design ideas:Define the class, the dialog reads into string s1, defines a char array

"). ReplaceAll ("W", "X"). ReplaceAll ("x", "Y"). ReplaceAll ("Y", "Z"). ReplaceAll ("Z", "A")) ; 3. Randomly generate 4-bit verification code, the user input and verify that the input is correct, if the input error to generate a new verification code to allow users to re-enter, up to 5 timesString str= "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";Char[]arr=new char[4];//defines an array of type char with a length of 4Random sj=new random ();System.out.println ("Verific

: Console input age, according to age output different tipsScanner sc=new Scanner (system.in);System.out.println ("Please enter an Age:");int Age=sc.nextint ();if (age>60){System.out.println ("You are old");}else if (age>30){System.out.println ("You are middle-aged");}else if (age>18){System.out.println ("You for Youth");}else if (age>13){System.out.println ("You are a teenager");}Else{System.out.println ("You Are Children");} Topic Seven: Enter the radius of the circle, calculate and outp