Java

October 3, 2016 10:36:40Have always wanted to write their own blog, one can share their learning experience, and then can be summed up in a timely manner, after all, the blog is written to everyone to see, need to pay more attention to each detail,

Less nonsense:the Java.util.Optional class can significantly reduce null judgments and NullPointerException exceptions. 1. Optional.ofOptional.of (null); //2. optional.ofnullableOptional.ofnullable (null); // no exception reported3.

It's a simple question! Configuring Java Environment variablesGet readyDownload install Java, official addressOpen the System environment variable, right-click on my ComputerJava_homeAdd Java_home, set the JDK installation directory, such as

Import Java.util.Scanner;public class Test10 {public static void Main (string[] args) {TODO auto-generated Method Stub/** int[] num=new int[4];** for (int i=0;i ** Char ch= (char) (Math.random () *26+65);** SYSTEM.OUT.PRINT (CH); }*/String number = "

Import java.awt.*;Import javax.swing.*;Import java.awt.event.*;public class Qqmain extends JFrame implements keylistener,actionlistener{Components for passing dataJTextField txtmess = new JTextField ();JTextArea txtcontent = new JTextArea

In the Test data dictionary tool class has been reported this error, looking for a long time, the original is springcontextutils this class did not put into the container.But I added a note on the springcontextutils, why didn't the note sweep?How

This is useful in the construction methodPeople.java Public classpeople{intLeg,hand; String name; People (String s) {name=s; This. Init ();//This can be omitted and will be This.init (); written as Init (); } voidinit () {Leg=2; Hand=2;

ImportJava.util.*;classExample2_5 { Public Static voidMain (String args[]) {intStart=0, End,middle; intA[] = {12,45,67,89,123,-45,67}; intN =a.length; for(inti=0; i//sorting arrays by Selection for(intj = i+1; J ){ if(A[j] A[i]) {

1. Pre-conditions 64-bit Linux operating system with Docker installed linux operating system image linux version of JDK compression package linux version of Tomcat compression package 2. start the container

We don't just want to prevent a thread from using a certain state, another thread is modifying it, and we want the other thread to be able to see the change in state after a thread has modified a state.First, visibilityReorder: In the absence of

Document EventThis event is a bit special, you need to return to the document you maintain with getdocument (), and then you can add a monitor(textarea1.getdocument). Adddocumentlistener (Documentlistener Listen)There are three methods of

classXiyoujirenwu {floatHeight,weight; String head, Ear; voidspeak (String s) {head= "Crooked Head"; System.out.println (s); }} Public classExample4_3 { Public Static voidMain (String args[]) {Xiyoujirenwu zhubajie,sunwukong; //declaring

Sort five integers in ascending orderpublic static void Main (string[] args)Int[] Nums=new int[5];int i,j; Loop variableint temp; Temp variableScanner input=new Scanner (system.in);System.out.println ("Please enter 5 integers");for

I. Write a simple calendar with the Calendar class of JavaPackage Com.calendar;import Java.util.calendar;import java.util.date;import java.util.gregoriancalendar;import Java.text.dateformat;import java.text.parseexception;import

[JAVA concurrent programming practices] 1. Object sharing and java practices1. Stack closures In stack closures, objects can only be accessed through local variables. Stack blocking refers to limiting the Declaration and Application of variables

Explain a piece of SQL? Or a code segment ?, SQL code I remember that my R & D colleagues who just entered the company could write beautiful SQL statements, and search was accurate, fast to execute, and highly efficient. To meet the requirement of

Cglib dynamic proxy and cglib dynamic The proxy adds a control layer for the access object to make it indirect. The control layer can add operation properties for the object access. Cglib: Code Generation library, High-performance code generation

Tomcat cross-origin access and tomcat cross-origin access What is cross-origin: Simply put, the browser requests resources between several different domain names. For security reasons, the browser rejects cross-origin access by default, leading to

Jvm gi collector, jvmgi collection   Garbage-First is a server-side Garbage collector. Parallelism and concurrency: Make full use of multi-core environments to reduce the pause time, Generational collection: No need to work with other

Unrecognized Windows Sockets error: 0: JVM_Bind exceptionUnrecognized Windows Sockets error: 0: JVM_Bind exception Solution Java.net. SocketException: Unrecognized Windows Sockets error: 0: JVM_Bind The cause of this exception is that the server