Java
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Java – eclipse autocomplete does not apply to lambda and types
I use eclipse oxygen 2 Release(4.7.2) I tried some lambda expressions and encountered the following problems: I write …… -
Is java 9 abandoning the SHA1 certificate or something else?
[update] Oracle has just revised its encryption roadmap（ https://www.java.com/en/jre-jdk-cryptoroadmap.html ）, they …… -
Beginner’s questions about heap and garbage in clojure
I have a question about clojure: (defn getAllPrimes [lim] (defn getPrimes [primes numlist] (if (not-empty numli…… -
Java – why mystring equals(“aString”); Different from “astring” equals(myString);?
I have heard many times that Boolean equals (object o) is used to compare strings. It is best to put the constant on t…… -
Java – the difference between loadclass (string name) and loadclass (string name, Boolean resolve)
What is the difference between loadclass (string name) and loadclass (string name, Boolean resolve)? The only differen…… -
How to check whether the class file version 50.0 (Java 6) has been pre verified?
I used Proguard to "upgrade" some jar files from class file version 49.0 to 50.0 Because pre validation is optional fo…… -
Print arrays in Java
I'm writing a method to print every object it passes By calling object The toString () method works, but not for array…… -
Java – bug about getbounds () and setbounds () on Linux_ Solution with id = 4806603?
On Linux platform, frame:: getbounds and frame:: setbounds cannot work consistently This was in 2003 (!) Report, see h…… -
java – MessageConsumer / MessageProducer vs QueueSender / QueueReceiver
Is messageconsumer / messageproducer equivalent to queuesender / queuereceiver? As far as I know, messageconsumer / me…… -
Java – polymorphism using Jackson to add subtype information at run time
I'm using Jackson to ungroup polymorphic types from JSON I use @ jsontypeinfo, @ jsonsubtypes and @ jsontypename annot…… -
Java – why can’t Tomcat find smtptransport (session, urlname)?
We have a web application that sends mail For some reason, its installation has decided that it cannot find the constr…… -
Java – multiple enumerations and one enum
When I stumbled upon something I didn't understand why, I was looking at the example implementation of publisher (asyn…… -
java. Lang. IllegalStateException: assetmanager completed
I went to bed yesterday while my application was working, and today I couldn't start when I tried to run it Once I try…… -
Java – why Catalina home_ IS_ The undefined directory is generated by logback in the same project directory?
I wrote the logback configuration file for my application, but when I was doing Maven clean install (MVN clean install…… -
How do I use JNDI to pass parameters to an LDAP custom socket factory?
I am using JNDI to establish an LDAP connection Example: Hashtable env = new Hashtable(); env.put(Context.PROVIDER_URL…… -
Java – best practice for testing indexof return values
What do you usually write when testing the return value of indexof? if str.indexOf("a") < 0 VS if str.indexOf("a") …… -
Java – you cannot use expressions to increment byte values, but use the increment operator
See English answers > why byte + = 1 compile, but byte = byte + 1 not? 8 byte i=0; i++; The following is invalid by…… -
Strange behavior of Java scanner reading files
Therefore, I encountered an interesting problem when using the scanner class to read content from a file Basically, I'…… -
Java – what is the default temporaltype for temporal mapping keys without @ mapkeycolumn or @ mapkeytemporary annotations?
I am creating a JPA 2.0 annotation compliance kit for my internship I know that when you use @ mapkeycolumn to define …… -
ADO. Optimistic concurrency in net Entity Framework
I found that an MSDN article describes how EF handles concurrency when saving changes: I have two questions: >There…… -
Java – someone can explain spring security basepermission Create?
I'm developing a project involving spring security ACL, and I encountered creating permission basepermission CREATE. S…… -
Java – hibernate 5: generator class = “sequence” does not work properly
I have the following mappings: <id name="id" type="java.lang.Long" column="id"> <generator class="seq…… -
Java 9 repl for running applications
Java 9 introduced repl. Exe called jshell in the JDK distribution Is there any way to connect to the jshell of the JDK…… -
Criteria – multiple expressions in the JPA querybuilder where clause do not work
I'm using javax persistence. criteria. Criteriabuilder encountered a problem creating the query I am using eclipse lin…… -
Java – iterator of wildcard type variables with upper bound
Hello, I'm trying to extend HashMap < string, string > to enforce the "all lowercase" rule public class HttpQuer…… -
How to convert vectors in 1 row table in R
In R, I have a 1 - row table How do I convert it to a vector? Specifically, the table is as follows: 0 1 2 3 4 21…… -
Nutch: using java calls instead of the command line?
Am I thick or really unable to programmatically call Apache nutch through some java code? Where are the documents (or …… -
How to use java8 lambda expressions to throw exceptions for custom checks?
See English answers > java 8: lambda streams, filter by method with exception 13 private static void readStreamWith…… -
Java – create only one object for the class and reuse the same object
I want to create only one object of a class and reuse the same object over and over again How can I do this? Solution …… -
Java – change fonts of different lines in jtextarea
I want to add different font lines in jtextarea, but the last font seems to overwrite another font Please help import …… -
Java – Jenkins build fails with svnexception
I'm trying to run Jenkins build Here is my configuration Jenkins version: 1.445 deployment: as war Java: 1.7 (server 6…… -
Java – the key in treemap returns null
So I have a very strange mistake When I first used keyset () to iterate over the first 10 keys of a large treemap, I s……