java code review tools

This section review Java Common I/O, input and output streams.First put the sample code, convenient reference, can be easily read. PackageRe08;ImportJava.io.*;ImportJava.util.Scanner; Public classIotest { Public Static voidMain (string[] args) {File file=NewFile ("D:/1.txt");//File Creation if(File.exists ()) {file.delete (); } Else { Try{file.c

("helloc3p0"); * 3. Gets the database connection from the DataSource instance. */@Test Public voidTestc3powithconfigfile ()throwsexception{DataSource DataSource=NewCombopooleddatasource ("Helloc3p0"); System.out.println (Datasource.getconnection ()); Combopooleddatasource Combopooleddatasource=(Combopooleddatasource) DataSource; System.out.println (Combopooleddatasource.getmaxstatements ()); } @Test Public voidTESTC3P0 ()throwsexception{Combopooleddatasource CPDs=NewCom

later4. Constants, variables:There is a lot of data in the program to represent the state of the program, some data will change in the process of operation, there areSome data will not change during the program's operation. These data are called variables and constants, respectively. Variable in theMust be declared before use: Data type variable name variables can be divided into: local variables, member variables, method parameters,Exception handling parameters.Local variables: Variables defin

1. What is the Java method?In our daily life, the method can be understood as the solution to do something and take it.In Java, a method is a way to accomplish something or to implement a function.Method implementation, there are a number of statements that are used to accomplish some meaningful function-usually working with text, controlling input, or calculating values.We can implement (or call) the metho

programs into bytecode and executes the compiled Java files through Java commands, which can bring good memories to the DOS-era programmer. This development tool is commonly used by Java beginners. From a beginner's point of view Java development tools, the use of JDK devel

1. Key wordsConcept: Words that are given special meaning by Java.Example: Declaring a class keyword: classAccess Rights keyword: publicstatic modifier keyword: staticNo return value type keyword: void2. IdentifiersConcept: A name used to standardize a custom in a programComposition: Alphanumeric underscore $Spec: Cannot start with a numberCannot contain spacesCharacters other than $ cannot appearCannot use keywordsNote: Identifiers in Java are strict

an exception.------------------------------------------------------Inner classStatic Inner classes: Create classes in classes, static adornments, and only static properties and methods of the perimeter class can be called.member Inner class: A class created in a class that cannot use the static modifier.Anonymous inner class: Creates an object directly in the method.Local inner class: A class that is created in the method body, has no modifiers, and can access only the final decorated constants

equals (object) method, then each object in both objects is called hashCodemethod must produce the same integer result, if two objects are not equal according to the equals (object) method, they hashCode do not require unequal calling methods, but for hash tables, the performance is best unequal. Therefore, we'd better rewrite.As mentioned earlier, the String class overrides the Equals () method, but the string class also overrides the Hashcode () method, which is the hashcode () generated from

class name can be called.After the method is static, it is easy to use, but the class can also be used by other programs to establish objects, in order to be more rigorous, forcing the class cannot establish objects, you can do this by privatizing the constructor .Person p = new person ("Zhangsan", 20);What has been done in this sentence?1. Because new uses Person.class, the Person.class file is first found and loaded into memory.2. Execute the static block of

our own defined Servlet class . 5. Servelt the relationship between core APIs UML diagram:6. The start of the servlet (default is a singleton servlet) (the Init method is executed the first time the servlet is called by default)• The servlet container loads the servlet at the following times:–servlet loading some servlets automatically when the container starts– After the servlet container is started, the customer makes the first request to the servletAfter the –servlet class file is updated,

, or has a default initialization value.Format: variable name of data type = initialization value;Categories of variables in 4.JAVA:A. Data type:Basic data type: Numeric type (integer type: byte/short/int/long; floating-point type: float/double)Character type (char)Boolean Type (Boolean)Reference data types: Classes (Class)/interfaces (interface)/arrays ([])Integer defaults to: int decimal default: DoubleB. Type auto-boost: High end Double/flaot/long Intàbyte/short/char5. Arithmetic operator: +-

Tomcat's lib. public class Hello extends HttpServlet {private static final long serialversionuid = 1L; JDBC driver name and database URL static final String jdbc_driver = "Com.mysql.jdbc.Driver"; Static final String Db_url = "Jdbc:mysql://localhost:3306/test"; The user name and password of the database need to be static final String user = "root" according to your own settings; Static final String PASS = ""; /** * @see httpservlet#httpservlet () */public Hello ()