Recent Posts
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Support covariant type conversion in Java
The Java type system only supports immutable types So list < string > is not list < Object > The list <…… -
Can the terms’ variable ‘and’ field ‘be used interchangeably in Java?
When learning java with several books, no one seems to be able to say when to use which term Variables are defined in …… -
Java – store multiple values in the mapping of a single key
I have the following name in C: ght Txt, which contains the following data Id|ytr|yts 1|W|T 2|W|T 3|W|T The problem no…… -
Java: Refactoring static constants
We are refactoring some code We developed a feature in one project and we want to use it in other projects We are extr…… -
Accessing subclass fields from a base class in Java
I have a base class called geometry, in which there is a subclass sphere: public class Geometry { String shape_name;…… -
Get metadata information of file owner using java
I am trying to retrieve the owner of the file using the following code: Path file = Paths.get( fileToExtract.getAbsolu…… -
Java – NullPointerException when trying to read parcel ArrayList
I have a class message that implements Parcelable It contains an ArrayList, and attachmentsdata is also one of my clas…… -
Java – creating CDATA sections is confusing
I tried to create a CDATA section in the description field, but failed The code is very simple, but there is no CDATA …… -
Java – Abstract generic class
I have the following courses: public abstract class Step { public abstract <S,T> S makeAStep(S currentResult…… -
Java thread, what is its answer?
The problem is from http://www.javacertifications.net/javacert/scjp1.6Mock.jsp start No problem - 20 What is the outpu…… -
Java – Dao and service layer in spring: session management
Do I correctly understand Dao & amp; Principle of service layer interconnection? The service layer uses the DAO ob…… -
Is there a detect method from Smalltalk in Java?
I search for method detection in Java 8 I used to use it in Smalltalk, but Java doesn't seem to have it Smalltalk's de…… -
Java – which implementation is better: a cache based on weakhashmap or a cache based on ThreadLocal?
It's hard for me to decide between the following two implementations I have written two POC implementations and am gla…… -
Java – a term that distinguishes between “default” and “makeup” classes in OOP
ArrayLists, buffer readers, scanners, etc All default classes that already exist in the language Unlike the public cla…… -
Java – Eclipse: some or all of the projects cannot be imported because they already exist in the workspace
Sorry, I know I often ask this question But the non scene suits my problem I use eclipse in Git (in win7) In the GIT b…… -
Java – get POM. From commandline XML attribute
I am currently writing a script for our gitlab Ci, which will automatically upload files to the nfsshare folder on the…… -
Java – jtextpane prevents scrolling in the parent JScrollPane
I have the following "tree" objects: JPanel JScrollPane JPanel JPanel JScrollP…… -
Java – how to implement list, set and map in null free design?
In most cases, it's great when you can return null / empty objects to avoid null values, but what about collections li…… -
java. net. Unknownhostexception: Test: Test: unknown error failed to get the local InetAddress of VMID
I'm in spring-jersey 1 C 3p0 is used for connection pooling in restful web services When I started the application, I …… -
Does Java’s split overwrite the length of the array, even if it is pre initialized?
String [] arr = {" "," "," "}; // String arr = new String[4]; String [] arr = {" "," "," "}; // String arr = new Str…… -
Java Concurrent HashMap
I want to convert concurrenthashmap to treemap Can I do that? Solution If you need a sorted concurrentmap, please chec…… -
Java – get the class name with generic information
In the Java serialization problem, I want to save some class names. I have some problems with generic classes Any idea…… -
Java – what are JPanel, JFrame, jlayeredpane and jrootpane
I am a novice in Java. When reading, I encountered various frameworks and panels. What is the confusion between JFrame…… -
java – Arrays. Contains (int) error
May I ask why the following output is false? import java.util.Arrays; public class Test2 { public static void m…… -
Java – given a string, does “XYZ” appear in the middle of the string?
My solution works without the second line, except for one condition: if STR = "xYx" is it possible to modify the for l…… -
Java is equivalent to Python’s string lstrip()?
I want to remove leading spaces from the string, but not trailing spaces - so trim () won't work I use lstrip () in Py…… -
Java – invalid or corrupt jarfile / usr / local / bin / selenium-server-standalone-2.38 0.jar
I tried to master unittesting and began to focus on this nettuts tutorial In this tutorial, it lets you download a jav…… -
Does the Java optimizer remember calculated values?
Which fizzbuzz implementation is more efficient? public static void fizzBuzz1(int n) { boolean fizzed,buzz…… -
Java – Method Parameter confusion
Usually, time methods require more than 3 parameters of the same type, such as void mymethod (String param1,String par…… -
Java – what did I do wrong with this quadratic formula?
a = 1,b = -7,c = 12 a = 1,b = -7,c = 12 public static void quadratic(double a,double b,double c){ double r1; …… -
How do I create a copy of the data type I created in Java?
If I have a class: public class MyType { private List<Integer> data; private boolean someFlag; …… -
Java – send commands between two computers over the Internet
I want to use any computer connected to the Internet at home to control my computer (and the USB device connected to t……