Java

1. RandomaccessfileJava provides an operation that allows random access to a file, and access includes read and write operations. The class is named Randomaccessfile. The read and write of this class is a pointer-based operation.　1) file access

Data type:The Java language is a strongly typed language that defines specific data types for each type of data, and allocates a different size of memory space in memoryClassification of data types:Basic data type:Integer:Number of bytes occupied

Why a character stream existsSince the byte stream provides the ability to handle any type of input/output operation, why is there a character stream? Let me slow down. The byte stream cannot manipulate Unicode characters directly, because a

Read Catalogue Recommendation 11: Develop a good habit and show the UID of the Declaration Recommendation 12: Avoid assigning values to invariants in constructors with serialized classes Recommendation 13: Avoid complex assignments

design principles : SOLID can be said that five design principles of each other.Single duty Principle (S): Design for classesOpening and closing principle (O): General guiding ideologyRichter Replacement Principle (L): Design for guiding class

In-system:is a way of rounding. X-Input, indicating every x into 1.The state of the computer's electronic components: open, close.Well, when we're expressing the data, it's also expressed in terms of the state of open and closed.If we express the

One, Java calls the Linux System command is very simpleThis is a very common example of calling methods:1 Publicstring Executelinuxcmd (string cmd) {2System. out. println ("got cmd job:"+cmd);3Runtime Run =runtime.getruntime ();4 Try

Reprint Please specify source:http://blog.csdn.net/ns_code/article/details/17382679one problem left in the article "Java Concurrent Programming Learning Note five: volatile variable modifier-unexpected problem" is that volatile only modifies the

* The non-static method belongs to the class instance, can be overridden by the quilt class, thus achieves the polymorphic effect;Static methods belong to classes and cannot be rewritten, and therefore polymorphic. *The following is a concrete

I made the mistake of the monkey to break the corn; now from the beginning: Success = feasible plan + execution forceWhat is maven?For:1> keywords: build, depend on, project information, Solution/gav, boast platform, open source/apache, distributed

1. java.lang.NullPointerExceptionThis exception is often encountered, the exception of the explanation is "the program encountered a null pointer", simply called an uninitialized object or a non-existent object, this error often occurs in the

What is an array:Q: Write code to save 4 students ' test scores.A: Simple ah, define 4 variables BaiQ: That "calculates the exam results of 400 students all year round", swollenFor:.......Array, you can help you to solve the problem properly!!An

In today's Internet Information development era, IT industry has become one of the hot industry development, the teacher of the education has said that Java has become the mainstream of the current, for Java programming we often will be common in

The concept of Java reflectionJava reflection mechanism is in the running state, for any class , can know all the properties and methods of this class, for any one object , can call any of its methods and properties ; This dynamic acquisition of

We often have to format numbers, such as 2 decimal places, which is the most common. Java provides the DecimalFormat class, which helps you to format numbers as quickly as you like. Here is an example:Importjava.text.DecimalFormat;

Public Static void Createdir (String destdirname) { new File (destdirname); if (!dir.exists ()) {// determine if the directory exists dir.mkdir () ; // dir.mkdirs (); // Multilayer directories need to call Mkdirs }}Note:

Reprint Please specify source:http://blog.csdn.net/ns_code/article/details/17161237There are two ways to implement multithreading in Java: inherit the thread class, implement the Runnable interface, in the program development as long as the

Jmail and jmail tools I haven't updated my blog for a long time. It's really a serious procrastination. It's terrible. Update a tool class first. I wrote a tool for sending emails. I don't need to talk much about the code. Import lombok. extern. slf4

The Difference and function of break, continue, and label. The differences and functions of break and continue:Break is used to completely end a loop [generally only exit a loop], and the statement after the loop is executed by the exclusive loop

The difference between Java member variables and attributes is simple and easy to understand !!!, Java Variables Example 1: A Student pojo class: public class Student {private String name; private int age; public String getName () {return this.