Recent Posts
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Java – why is an object sometimes null when it is initialized in a thread and accessed from main?
When I create a new object in a thread, it is a property of an object. I give the thread that it remains null in the m…… -
How to link Java HashMap? How do I access all collision values?
I read somewhere that HashMap uses links to resolve conflicts But if so How to access all elements with the same key v…… -
Java – advantages of locking API synchronization
Every blog or explanation I see the advantages of locks API over synchronization I want to know what the advantages of…… -
I got Java lang.NoClassDefFoundError：org / springframework / web / context / WebApplicationContext
I added spring - web. Net to my classpath 4.0. jar. It contains the class – org springframework. web. context. WebAppl…… -
Clojure – why can’t let be used with vector?
replace (let [x 1] (my-expression)) I'm trying to use: (let (vector x 1) (my-expression)) Don't ask why, I prefer ordi…… -
Java – the best way to initialize ArrayList and HashMap?
Suppose I want to create an ArrayList for numbers The way I learn it is this: private static List<Integer> numbe…… -
Java: questions about immutability and finality
I'm reading "effective Java" In the project of minimizing variability, Joshua Bloch discussed the problem of making a …… -
Java – is this singleton thread safe?
I have a singleton server instance, and I'm curious if my code is thread safe I've read for different singleton modes,…… -
Java – why are there unhandled exceptions in this code?
I am from the following code: class Animal{ public void eat() throws Exception {} } class Dog extends Animal{ …… -
Java – store axis raw XML request / response in the session (to be used in JSP)
If possible, how do I get the original XML request / response that Axis called / retrieved in my application? I am usi…… -
Java stream orElseThrow
I want to convert a piece of code from a connection pool project that I've been trying to use streams The original cod…… -
Java – guava cachebuilder delete listener
Please tell me where I lost it I have a cache built by cachebuilder in datapool Datapool is a singleton object. Its in…… -
Java – the difference between declaring ArrayList under polymorphic and normal conditions?
What is the difference between declaring an ArrayList in such a polymorphism: List<Integer> iL = new ArrayList&l…… -
Java – how to reference a wicket page with parameters
I need to send wicket links (e.g. by email) to reference instances in the system For example, a message might contain:…… -
Java – remove eclipse symbols
I had these strange symbols one day. I wasn't sure how I got it or how to delete it I really don't know why these are …… -
Java – the fastest byte array connection method
I get a mapping containing the N part of the message as a byte array After the last article enters the map, you must c…… -
Java – strange tochararray () behavior
I'm trying to use tochararray () and found some strange behavior Suppose private static final char [] hex_ CHARS =“012…… -
Java – use XSLT to convert XML to HTML
What I'm doing: I'm trying to convert XML to HTML using XSLT Problem: if the program is executing without any errors, …… -
Java calculator with multiple operations
So far, I have the following working normally I'm sure there may be a simpler way to do this, but what I need to chang…… -
java – Reflection Class. Forname() looks for classes $1 and $2. What are they?
See English answers > java compiled classes contain dollar signs When checking the string input userinput, see if a…… -
Java,UnsupportedClassVersionError. How can I solve this problem
I was doing my homework during the solar eclipse. It didn't report an error or even a warning When I tried to compile …… -
Java – deletes the last line from StringBuilder without knowing the number of characters
I wonder if there is a simple way to delete the last line from the StringBuilder object without knowing the number of …… -
In Java, if null pointers rarely occur, it’s best to use catch instead of if
Clean up some loose in my Android application. I found a null pointer exception in the developer console. This has nev…… -
Java security class cast exception
Hi, I'm a beginner of Java security. I encountered the following problems when calling: Cipher cipher = Cipher.getInst…… -
Java: basic math errors?
I have to do something fundamentally wrong here My code is very simple: private static final long MILLIS_PER_YEAR = 10…… -
How is it different to declare a java interface method signature as final and non final
How is it different from declaring a method signature as final and non final in a java interface? int setName(String n…… -
Numericupdown equivalent in Java
It should be easy, but I didn't find it in Google: In Java Net system Windows. Forms. Does numericupdown have an equiv…… -
How to convert Java long to * unsigned * base-x string (and return)?
[editor] I don't accept any answers involving BigInteger or other similar inefficient methods Please read the question…… -
Java robot class – add focus to a specific running application?
I just want to find out if / how to let the Java robot class change the focus from a running Java application to a spe…… -
java – Runnable. When can tostring() return duplicate strings?
this. When might tostring() return a duplicate string? public static void main(java.lang.String s[]) { for(int i=0…… -
Java – why string “= =” in equals?
Why does Java compare (this = = another string) in the equalsignorecase method to check that the string is insensitive…… -
The work of garbage collector in Java
Calling system What objects are available for garbage collection when gc()? Why? public class GCTest { static clas……