URL is not hierarchical ...
String b = "abcd " String a = "a " String c = "bcd " String d=a+c system.out.println (dashed constants) false Why false should be true according to the principle that there is only one copy of the java string constant. what does the memory d...
the java interface should not be instantiated, so why make the program work properly in the following form? (the screenshot on the ebook, the program actually clicked, but I don t know why) ...
java rookie, read java Core Technology introduction Graphics2D class is a subclass of Graphics, in which there is a code public void paintComponent (Graphics g) { Graphics2D g2 = (Graphics2D) g ...... } will there be no error in the downward transitio...
objects are transmitted in binary mode on the network. so for serialization, different serialization, the transferred object should be a binary stream. then why json and xml are also described as serialization. It is not very clear that both of them ha...
< H2 > NewFile.java < H2 > private File configurationFile; public NewFile(File file){ this.configurationFile = file; } public void newFile() throws IOException{ if (!configurationFile.exists()) configurationFile.createNewFile(); ...
the first code can be locked successfully public class Main { public static void main(String[] args){ LockThread lock1 = new LockThread(true); LockThread lock2 = new LockThread(false); Thread thread1 = new Thread(lock1); Thread th...
but what if I call system.in.read () again after closing it? does its instance BufferedInputStream shut down automatically immediately after it is used up? Or are you waiting for recycling? ...
Student.java private int age; private String name; public Student(int age, String name){ this.name = name; this.age = age; } public void setAge(int age) { this.age = age; } public String getName() { return name; } public void setNam...
for example: $str = 123123 ; preg_match_all( ( d*) , $str, $arr); var_dump($arr); or: exec("date", $output); var_dump($output); this is not declared $output , and can be output as $arr ? What is the reason for this? add <?p...
Server: Aliyun system: Ubuntu 16.04.4 after installing nginx, I deleted the default of etc nginx sites-enabled using ln-s etc nginx sites-available default etc nginx sites-enabled default to establish soft link, reload nginx service, it is ...
The icon "+ " appears in v-for, which one is clicked and which becomes "added ", all of which have changed with one click. The code is as follows: ...
this is the url.py in the project blog from django.urls import path from . import views urlpatterns = [ path( , views.index, name="index"), ] this is the url.py in the root directory from django.contrib import admin from django.urls ...
there is a key such as flag in sessionStroage, how to listen for changes in its value. Is there any other way to access this data at regular intervals with a timer ...