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Java : I am new to Java and working on a problem where I need to group and aggregate a collection based on the below Matching key , this key is a combination of properties from below mentioned classes.The DailyOCF collection is populated in an ArrayList , sample data provided below.The above list needs to be grouped ba... | Group and Aggregate by multiple properties based on complex matching key |
Java : I am a bit new to LinkedList and I want to practice by making methods in ExampleLinkedList class . There is a list in test3 . When I call test3 I get Goodbye Thanks Hello . What I want is to add `` AddedItem '' in the end of the list to get AddedItem Goodbye Thanks Hello but I get only AddedItem as a result . Ho... | Adding a Object to End of a Linked List in One Class |
Java : To write a good comparations test test you have to run it several thousands ( millions ) times . It will level ( in most cases ) other programs ' influence . But if a JVM can influence on the results . For example : First solution is : And second is : I do not know which one is better because JVM can influence o... | How do to perform a good performance comparations test ? |
Java : Which Java synchronisation object should I use to ensure an arbitrarily large number of tasks are completed ? The constraints are that : Each task takes a non-trivial amount of time to complete and it is appropriate to perform tasks in parallel.There are too many tasks to fit into memory ( i.e . I can not put a ... | Synchronisation object to ensure all tasks are completed |
Java : I 'm not exactly sure why this causes a stack overflow . I know if I call the someMethod method without the instance it works fine , but I 'd like to know why.Thanks <code> class test { public static void main ( String [ ] args ) { test item = new test ( ) ; item.someOtherMethod ( ) ; } test item2 = new test ( )... | why does this object cause a stack overflow ? |
Java : I have some output from a ( C++ ) application that stores a tickcount value in a type that wraps to zero at 233 . ( 8,589,934,592 ) ( Do n't have the code ) I need to write my own output in the same way . I retrieve the tickcount from a C lib through JNA , but if I store it in an int it wraps to -231 ( -2,147,48... | Simulating unsigned number with a certain power of two max in java |
Java : Below is the parent class DblyLinkListBelow is the derived class LockableList , If class LockableNode < T > extends DListNode < T > in the above code , error : The constructor DblyLinkList < T > .DListNode < T > ( T , DblyLinkList < T > .DListNode < T > , DblyLinkList < T > .DListNode < T > ) is undefined occurs... | How to inherit parent 's inner class in this code ? |
Java : The simplest code to demonstrate the issue is this : Main interface in Kotlin : Abstract class implementing it and the method : Java class : It should work , but it does n't . The error is Class 'JavaImpl ' must either be declared abstract or implement abstract method 'go ( T ) ' in 'Base'If the JavaImpl class w... | Extending Kotlin class by Java requires me to reimplement already implemented method |
Java : there is an error on the last line this looks perfectly fine to me , but maybe i am missing some subtlety on how type wildcards work . Is there a way i can change the type on the last line ? i need this reference because i plan on doing this later : this also has an errorhowever , if i use it without the wildcar... | why doesnt this type wildcard work ? |
Java : I 'm using the following code to convert a hexadecimal String to a floating point String : To test this , I wrote the following JUnit test : However , the 2nd assertion fails . According to various online converters like this one , 50000000 should be converted to 8589934592 but Java returns 8589934600.Which resu... | Hexadecimal - > Float Conversion Inaccurate |
Java : I am trying to track down why a specific behavior is happening with .orElseThrow in a Java Stream . This code block results in this error : unreported exception X ; must be caught or declared to be thrownI do n't want to report the exception because that would cause me to add that to every other method who inter... | Java8 Stream .orElseThrow unreported exception error |
Java : I have a list of `` Item '' objects list like : Is there a way to `` unpack '' those object using streams to have a list of items eventually repeated if qty is greater than 1 so at the end I 'll have objects with qty equals to 1 ? <code> public class Item { private String name ; private int qty ; public Item ( )... | Java stream how to unpack a object with quantity to list of single object |
Java : I 'm writing a java program that print seconds elapsed , and every 5th second it will print a message . This is a sample output : How can I remove the boolean variable printMsg ? Is there a better thread design that allow this ? For now , without printMsg the program will print multiple `` hello '' during the 1/... | Multiple threads with notifyAll ( ) |
Java : Given this code ... Imagine that instead of this while ( true ) you have something that does not throw interrupted execution ( for example , a recursive function that actually calculates something ) .How do you kill this thing ? And why is it not dying ? Note if I do n't put Exception type there and use Interrup... | Impossible to interrupt thread if its actually computing ? |
Java : This is from Thinking in JavaHere is my Java enviroment : java version `` 1.8.0_60 '' Java ( TM ) SE Runtime Environment ( build 1.8.0_60-b27 ) Java HotSpot ( TM ) 64-Bit Server VM ( build 25.60-b23 , mixed mode ) <code> class Snow { } class Powder extends Snow { } class Light extends Powder { } class Heavy exte... | Why is there no type conversion exception in this code ? |
Java : Java is smart enough to determine whether an integer is small enough to be converted to a character . Why is it not able to convert very small floating point literals to a float ? . For example : char c = some integer literal might compile but float f = some floating point literal will never compile . Why ? PS :... | char c = some integer literal might compile but float f = some floating point literal will never compile . Why ? |
Java : I have following code : Eclipse gives a `` dead code '' warning on the return null ; . Removing the test for keyValue == null also removes the warning but I do n't see how that extra test makes the return statement dead code . Clearly if the map contains no entry for some non-null keyValue , then rowIndex can st... | Eclipse gives dead code warning for reachable code ( variant ) |
Java : I am looking to select a design pattern for a project I am working on and was wondering if I can get some input . BackgroundAn interface called Ranker is defined as follows . Each implementation of Ranker can have multiple Rankers as member variables and each of the member Rankers can have multiple Rankers as th... | Dilemma while selecting a design pattern |
Java : In my study book , there 's this example : I find it strange that it compiles , since there is no definition of Class < T > . What is the story about this ? It says in my book that T is for the type parameter but how do I know when to use it ? <code> import java.util . * ; public class RentalGeneric < T > { priv... | How to understand this use of Java generics |
Java : I am making a program in which a pool of x number of threads interacts with a shared inventory . In this case I use an ArrayList as the shared inventory . In my program the threads are representations of jobs that a creature has . Creatures belong to a party and share a pool of Artifacts used to perform jobs . o... | Threads not communicating |
Java : I have the following class.What is the -keep option that will ensure the constructor wo n't be removed by Proguard ? The following will keep the constructor ; however , I do n't want to have to specify every single class or package . <code> public class StatusCategory { @ JsonProperty ( `` key '' ) private final... | Keep constructor if field annotated |
Java : I have two corresponding lists : The goal is to sum discounts , which means adding discountRate from actualPromotions to discountRate value from the booksToReturn list . The objects from both lists can be matched by idOfBook.This is how I solved it I 'm just exploring streams and I think my solution is clumpy . ... | Update objects in one list based on values from second one using streams |
Java : I want to be able to write an aspect to detect when I am casting something in one of my org.mypackage classes.How do you write a pointcut to express the casting operation , not just for Foo class , but for any class in org.mypackage ? Background : So Hibernate 5 + Spring Data JPA requires casting entities with i... | AOP To Detect All Class Casts For Hibernate.unproxy ( ) |
Java : It says I 'm supposed to write : On the settings.gradle file according to : https : //docs.gradle.com/enterprise/gradle-plugin/But then I get an error saying:2 : Only Project build scripts can contain plugins { } blocks <code> plugins { id `` com.gradle.enterprise '' version `` 3.5 '' } gradleEnterprise { server... | I ca n't apply the gradle 6.x plugin |
Java : Here , my main goal is setting the value safely , without having a performance ( speed , memory , cpu etc ) impact.I have a silly option ( in a bad style ) also mentioned below . So , what is the best way to do this ? option 1 ? option 2 ? or another one ? Option 1 : Option 2 : Note : this piece of code is in a ... | Using try-catch over if conditions to safely set values with minimum performance impact in java |
Java : ProblemI am writing automated tests for my company 's website using Java and Selenium . Right now I am writing tests that involve clicking on links , and verifying that the link leads to the correct place . We have a newsletter popup ( from BounceExchange ) that appears at very unpredictable times , and it 's ca... | How do I stop email newsletter popup from intercepting clicks ? |
Java : I 'm writing a library method that will be used in several places . One of the method 's parameters is a collection of objects , and the method does not mutate this collection . Should the method signature specify a mutable or immutable collection ? Option 1 : mutable collection as parameterPros : Clients can pa... | Preferring mutable or immutable collections as method parameters |
Java : I am getting the below error : Monitor.javaWebScoutCallable.javaContainsMonitor.javaI 'll freely admit that I 'm new to generics and still quite new to Java itself . I find the error message confusing as it looks like it should work ( method declaration expects a Monitor or subclass , I 'm passing in a subclass ... | Why does this method call fail ? ( Generics & wildcards ) |
Java : My code is : The output is I really have no idea why only c [ 0 ] has changed . <code> public class MyProgram { public void start ( ) { int a = 1 ; int [ ] b = { 1 , 2 , 3 } ; int [ ] c = { 1 , 2 , 3 } ; method1 ( a , b [ 0 ] , c ) ; System.out.println ( `` a = `` + a ) ; System.out.println ( `` b [ 0 ] = `` + b... | I cant figure out how this void method works |
Java : Let 's say my original Map contains the following : And I want to create a reversed Map containing the following : I know it can be done in old fashion ( pre-Java 8 ) , but how do I achieve the same using Java Stream API ? There 's similar question posted here , but that only works for single valued Maps . <code... | How to create a reverse map when original map contains collection as the value ? |
Java : This is a piece of code in a SCJP practice question : It was partly mentioned here.However , my question is not the prior question . As I run the program on a few machines multiple times , I occasionally get RuntimeException before `` run '' in the output . This does not make sense to me , as these lines of code... | Codes on the same thread executed in unusual order |
Java : Please look at this code : result：console print： 0 9 I know that subclass will first calls the superclass constructorbut , why is the 0 9 , not 8 9 ? <code> class Sup { int a = 8 ; public void printA ( ) { System.out.println ( a ) ; } Sup ( ) { printA ( ) ; } } public class Sub extends Sup { int a = 9 ; @ Overri... | Java - extends why the super variable a is 0 |
Java : Here 's the snippet : As the code above , Even if we put LoggerThread.interrupt ( ) in stop ( ) method , the interruption just be caught by thread and do nothing.So is LoggerThread.interrupt ( ) necessary ? <code> public class LogService { public void stop ( ) { synchronized ( this ) { isShutdown = true ; } logg... | Is this interrupt ( ) necessary ? |
Java : I 've seen plenty of ways to sort a list of objects that work fine if you know the incoming keys or at least the incoming number of keys.Problem is in my case I do n't know if the user will send in 1 or 10 keys.Currently I have a giant switch statements for each number of keys , but obviously that scales terribl... | Sort a list of objects based on an unknown number of keys |
Java : output : 1121output : 4 4 5 5For above code why both objects are not referring to same memory location . <code> public static void main ( String [ ] args ) { Integer a = 1 ; Integer b = 0 ; b=a ; System.out.println ( a ) ; System.out.println ( b ) ; ++a ; System.out.println ( a ) ; System.out.println ( b ) ; } p... | Copying one object to another Object is yielding different results in java |
Java : Need to find out if a given string contains just a particular digit only - e.g . `` 111 '' , `` 2 '' , `` 33 '' should return true . `` 12 '' should return false.Empty string ( `` '' ) should also return true.The string contains only digits and no other characters.Wrote an ugly Java regex that seems to work , bu... | Check if string contains a particular digit only ( e.g . `` 111 '' ) |
Java : Create a class likeand it compiles in Java 8 ! ( Both in Eclipse 4.5 and JDK1.8_25 ) https : //ideone.com/Q9JLHPIn Eclipse , all the bounds are inferred correctly , but how could outer 's capture Supplier < ? super Integer > ever been satisfied by the argument Supplier < String > ? ? Edit : clarified this is Jav... | Type checking broken on matching capture with upper bound ? |
Java : I have a Java thread with a run method that computes many things . You can think of it as a series of math statements as follows . Note that each computation may utilize other methods that in turn might have additional loops and such.There is a GUI that prints the output of these statements as they produce their... | Java - terminating a method within a Thread |
Java : I have an interface A like this : And then I have this class : I have n't use generics before ( only things like List < String > ... ) so I ca n't see why this code does n't compile . To be more precise , I get an error on the line elements.add ( obj ) ; that the method add is not applicable for these parameters... | Java using Generics |
Java : I 've a query as follows ... That I 've achieved through , Creating a connection , statement & executing the query as followsBut , now I need to find whether the code had performed an INSERT or UPDATE ? Can anyone help me with this ? ? Thanks in advance ... <code> INSERT INTO MYTABLE ( f1 , f2 , f3 , f4 ) VALUES... | Finding wheather the mysql query performed a update or insert |
Java : Let 's say I 'm using Java 11 javac , but I 'm using the -- source and -- target options set to 1.8 so that my source code will be considered Java 8 and the output .class files will be compatible with Java 8 . My goal is to produce .class files that can run on a Java 8 JVM.And let 's say I have the following Jav... | How should javac 11 link methods overridden in later versions with a Java 8 target ? |
Java : I have a document that says the average case time-complexity for the given code is O ( nlog2n ) I have computed the best and worst cases as : Best case , k = n leading to time complexity of O ( 1 ) . Worst case , k = 1 leading to time complexity of O ( n ) . How can average case be O ( nlog2n ) , which is higher... | time complexity : why O ( nlogn ) ? |
Java : Can you explain me why the result is `` int '' ? I would expect it to be `` long '' provided the variable is a byte . <code> public class Test { public static void printValue ( int i , int j , int k ) { System.out.println ( `` int '' ) ; } public static void printValue ( byte ... b ) { System.out.println ( `` lo... | Java Primitive Widening Interview |
Java : In situations such as the one above , I like to put the else in the end so I can be notified if the program runs code it should n't run , meaning something went wrong ( i.e . one of the above conditions should be true , but none are , which means something is wrong ) .What exception should I throw in that final ... | What exception should I throw when code which is n't supposed to run is run ? |
Java : We knows that TPL ( so PLINQ too ) does n't consume all cores if he think that task is easy and executes it on single core . But he does it even for a complicated task ! For example , here is code from article about Java parallelism : and results : you can see that multithreaded version executed ~19 times faster... | What heuristic uses TPL to determine when to use multiple cores |
Java : I have a rather peculiar problem . I 'm trying to find a pattern like [ some string ] [ word boundary ] . Simplified , my code is : My logic tells me this should always output true , regardless of what someString is . However : if someString ends with a word character ( e.g . `` abc '' ) , true is outputted ; if... | \b does n't match when the preceding character is a word boundary |
Java : I would like to know how to shorten my code with the help of Stream Api.Let 's say I have method like this : And I would like to call this method 5 times with the same parameters . For exampleI know I can do something like this : But here I am passing one integer value to method . Anyone can give me some hints o... | How to use stream api for repeatable actions |
Java : I realize that the results for string1.compareTo ( string2 ) will be a number -1 or below if string2 comes before string1 alphabetically , and a number 1 or above if different the other direction . I need to return only -1 , 0 , or 1 . I can code it in a seemingly clunky way , but I feel like there must be a mor... | How can I best restrict String.compareTo ( ) results to -1 , 0 , and 1 ? |
Java : I have an enum class which has several constants , and I want to add some static value FOCUSED which indicates which of the enum values has focus ... I found a way : However , now I wonder : Did I just mess with the enum class ? Because I do n't want FOCUSED to be selectable when specifying the message type , ho... | Enum : Did I just do something unwanted ? |
Java : I 'm curious if there 's a syntactic way to extend JSONArray such that I can then use it in a for ( : ) loop as I can a List.So , instead of having to do : I would like to doI realize that I need to make sure that in the above example the object in the array is indeed a String , but given that JSONArrays can onl... | Is there a way to overload JSONArray to behave like a regular List in a loop ? |
Java : Hey if anyone has an idea I would be really thankfull.I 'm in a Java stream and i would like to sort my list that i 'll be returning.I need to sort the list via TradPrefis ( MyObject : :getTradPrefix ) .But this would be way too easy . Because i want to sort following the number at the end of TradPrefix exampleT... | Private Sorting Rule in a Stream Java |
Java : I 'm currently working on my Bachelor Thesis about how to write effective Java code . The following four code snippets are part of a JMH benchmark which will execute every method 1 million times each.The results for this four methods are : primitiveOnly : 1.7 ms/operationprimitiveToWrapper : 2.2 ms/operationwrap... | How does Java decide which operator in a math expression has to be ( un ) boxed ? |
Java : I 'm working on a game where you can upgrade your stats in a shop . When you buy something it should refresh the JLabel which shows your CoinsIs there a way to do that without doing a new JFrame ? This is the code of the ActionListener where I want to refresh the JFrame epixHere 's the code of the View <code> pu... | refresh JFrame Java without doing new JFrame |
Java : I have an user story in Rally which has a feature set as parent . I want to update the parent artifact via Java API to another user story . However I am getting a validation error while doing so i.e . I added following property to include in the UpdateRequest : How to override this validation , can anyone please... | Unable to update user story in Rally via Java API |
Java : Java 8 's String.replaceAll ( regexStr , replacementStr ) does n't work when the regex given is `` .* '' . The result is double the replacementStr . For example : I know replaceAll ( ) does n't exactly make sense to use when the regex is `` . * '' , but the regex is n't hardcoded and could be other regex strings... | Why does String.replaceAll ( `` . * '' , `` REPLACEMENT '' ) give unexpected behavior in Java 8 ? |
Java : I used this Topic I try this code but did not work : PACKAGE_NAME = context.getApplicationContext ( ) .getPackageName ( ) ; But it could not help me . I have the application list , I want to get the permission that used on each of them.How can I handle it ? UPDATE : like the photo , When clicking on `` دسترسی ها... | How give the application manifest permissions ? How to do it programmatically on Android ? |
Java : What is wrong ? I assume that if I subtract 1ms from 1 Jan 1980 0:0:0 then I 've got 1979 . But I must subtract about 500+ ms for this . Please , give me a hint.Updated.The solution is <code> val cal = Calendar.getInstance ( TimeZone.getTimeZone ( `` UTC '' ) ) cal.set ( 1980 , 0 , 1 , 0 , 0 , 0 ) val date = new... | Subtraction of 1ms leads to unexpected behaviour |
Java : I am currently working on a tic tac toe program for an assignment . The issue I am having is when I count my player ( either the ' X ' player or the ' Y ' player ) , it seems to be counting both players as the same . For instance , after the third play , it sees three plays and counts it as a winner , even thoug... | Compiling Issue ? |
Java : It seems I 'm stuck with java generics again . Here is what I have : Couple of classes : class CoolIndex implements EntityIndex < CoolEntity > class CoolEntity extends BaseEntityEnum using classes above : Function I need to call with use of result of getIndexCls ( ) function call : The problem is that compiler c... | Incompatible classes of java generics |
Java : I would like to be able to compare two versions of a class / library to determine whether there have been any changes that might break code that calls it . For example consider some class Foo that has a method in version a : and in version b the method becomes : or something similar in the case of a field : I wo... | Tool to look for incompatabilities in method signatures / fields |
Java : I have a simple coding scenario like : My question : Is there any way to handle exception in catch ? if yes , then how ? What if finally block have exception , is there any way to handle them ? Or Is it only bad programming practise to have an exception in catch or finally block ? <code> class A { public static ... | If the catch throws exceptions , how should I handle them ? |
Java : Today I tried to solve a small challenge : You are a big company with 500 offices , you want to compute the global revenue ( sum of revenues of each office ) .Each office exposes a service to get the revenue . The call takes a certain delay ( network , db access , ... ) .Obviously , you want global revenue as fa... | RxJava usage optimization request |
Java : Referencing a previous answer to a question on SO , there is a method used called TestForNull . This was my original code before I was told I could make it more efficient : My original code : In this snippet , I 'm doing three look-ups to the map . I was told that this could be accomplished in just one lookup , ... | Map Lookup Efficiency of TestForNull |
Java : I have this piece of codebut I have a compilation error <code> List < BookDto > deskOfficer = delegationExtendedDto .stream ( ) .filter ( Objects : :nonNull ) .filter ( d - > d.getMembers ( ) ! =null & & ! d.getMembers ( ) .isEmpty ( ) ) .map ( d - > d.getMembers ( ) .stream ( ) .filter ( Objects : :nonNull ) .f... | Collecting Lists in Java 8 |
Java : I have an String array with multiple items.Now I want to check in if condition likeIs there any method that can check whole array and if list [ i ] present in array then go into the if condition block.Thank you in advance . <code> String [ ] folder= { `` proc '' , '' root '' , '' sdcard '' , '' cache '' , '' sys... | How to get array item without looping in android ? |
Java : How do I read/understand the following statement in Java ? I think I can understand them individually but I do n't know if I get good sense of what it means in its entirety . Individually : Class < ? > means any class and Class < ? extends Payload > means any class that extends the Payload class [ ] seems to ref... | What is the syntax for annotation type elements ? |
Java : I 'm trying to use java class BitSet as a field for a customized class . And I want the class to use a default BitSet with all bits set.By default BitSet constructor unsets all bits . So before I send it as an anonymous object , I would like call set ( int , int ) method to set all bits . I know that I could sim... | Can object method call be done simultaneously with object instantiation ? |
Java : Consider 4 input fields A , B , C and D on a web surface . The user can fill any of these arbitrary . There are 16 combinations of how to fill these fields . The ones allowed are : where 1 means not null and 0 means null . I am using the MVC pattern with jsf . I do n't want the logic to be in the view , but rath... | What is the best way to test this ? Binary digits with 4 positions |
Java : I created a javaFX chooser file in Jython . It was n't easy to port from Java to Jython , but in the end some results came . Now I would like to parameterize the obtained class , taking into account the file filters , so as to be able to use the object for browsing different from the type of filtered files.I tri... | Add file filters to JavaFx Filechooser in Jython and parametrize them |
Java : I want to set first spinner value as `` select your choice '' then shows the data from serverone solution * creates another array list and in that list contain the value `` select your choice '' and combine these two and set to the spinner .. how can I achieve this please help me ... ( using cursor ? ? ? ? ) met... | Add a first value to spinner when spinner data is came from server |
Java : This is a copy of code that I run on a tomcat server on a scheduler . When I check the status of the server I can see the no of open files increasingThis is the command used to check open files sudo lsof -p $ ( pidof java ) | grep `` DIR '' | wc -lThis is an example of the code wrapped in a unit test.Eventually ... | Java 8 reading file list , but files remain open using up resources till server freezes |
Java : I have a data Set like this : Which I 've loaded in ArrayList of String [ ] from Text file like this : I wanted to sort data set in increasing year like this : Problem : The built-in sorting method Collections.sort ( list ) ; of ArrayList only works on single type of data . But , in my case I have string with mu... | Sorting multi-type string ArrayList in Java based on Integers |
Java : I would like to split a string : '' x= 2-3 y=3 z= this , that '' I would split this up on one or more whitespaces , that are not preceded by a '= ' or a ' , 'meaning group one : `` x= 2-3 '' two : `` y=3 '' three : `` z= this , that '' I have an expression that kinda does it but its only good if = or , has only ... | Java regex split on whitespace /not preceded |
Java : Lets suppose I have a ComponentBase class , who is child of ObjectContextDecorator and grandchild of ObjectContext.The set methods on ObjectContextDecorator and ObjectContext are very simillar . Consider this sample code : Both methods ' signatures fit the one being called correctly . I am not able to change the... | Overload resolution , which method is called |
Java : Is the class listed below a singleton ? Since the constructor is declared as public , can I infer that the class is a singleton with wrong implementation ? <code> public class CreateDevice extends Functionality { private static Simulator simulator ; ConnectionDB connect = ConnectionDB.getInstance ( ) ; public Cr... | Is this class a singleton ? |
Java : How do I get result set as { GERMANY=3 } instead of { GERMANY=3 , POLAND=2 , UK=3 } The outcome as given below I want like below . <code> public class Student { private final String name ; private final int age ; private final Country country ; private final int score ; // getters and setters ( omitted for brevi... | How do I get max country for a given arraylist |
Java : I can not compile the following piece of code ( try at onlinegdb ) : incompatible types : can not infer type-variable ( s ) T , U , A , R , capture # 2 of ? , T , T ( argument mismatch ; invalid method referencemethod getDifference in class Container can not be applied to given typesrequired : no argumentsfound ... | Collectors.maxBy ( Comparator.naturalOrder ( ) ) does n't compile although Long is inferred |
Java : I have a string which may have one of two formats : ( someName , true ) ; ( where someName can be any combination of letters and numbers , and after the comma we have either true or false ) ( someName , true ) , ( anything , false ) , ( pepe12 , true ) ; and in this case , we can have as many parenthesis groups ... | Repeating the same pattern on a regex in java ? |
Java : i have a following code : It will return a price like `` 7,49 $ '' . I want to replace this code with java 8 features . I 'm newbie with streams , but tried : But it returns < meta itemprop= '' price '' content= '' 7,49 $ '' > I ca n't filter like this ( missing return statement ) : How to fix it ? <code> @ Over... | Replace for loop with lambda |
Java : I have recently converted over an android project into androidx and I am having issues with trying to stop views going off of the page . My layout is as follows , a Constraint Layout that contains a Card View and a Text View . Within this Card View I have a Constraint Layout that contains the Text View . Outside... | How to fix a view from going off of a page when it is constrained to a card view |
Java : A while back , I was working on a programming problem ( CCC ) . I have also come across similar questions in past contests so I decided to ask about this one . The problem is basically this . You are given n people and p pieces of pie.n people are standing in a row.You must distribute p pieces of pie amongst the... | Converting simple recursive method which recurses within a loop into iterative method |
Java : I have the following array of code types : and the following ids : I want to extract the code type from the idsthis is my code snippet : it doesnt work with the 1st id , because it returns `` code '' instead of `` sample_code '' , I want to get the longest code type . <code> [ `` sample_code '' , '' code '' , ''... | JAVA return longest value if a string contains any of the items from a List |
Java : Why an actual number string read from a text ca n't be parsed with method Integer.valueOf ( ) in java ? Exception : This is my code <code> Exception in thread `` main '' java.lang.NumberFormatException : For input string : `` 11127 '' at java.lang.NumberFormatException.forInputString ( NumberFormatException.java... | Why an actual number string read from a text ca n't be parsed with method Integer.valueOf ( ) in java ? |
Java : In the project I 'm working on ( not my project , just working on it ) , there are many structures like this : And the Service is called like this : I understand that a factory is used to hide the implementation of MyServiceImpl if the location or content of MyServiceImpl changes . But why is there another facto... | Why do I need a FactorySupplier ? |
Java : I have the following scenario : two validation Helpersthe StringValidationHelper ... ... and NumberValidationHelper.The method from is a static factory method that receives a Predicate and a message to eventual validation fails.Thanks to the Validation interface , you can enjoy a wonderfully smooth interfaceSo I... | How to generalize a static clousure ? |
Java : I want to create a map of comparators as following , this map will be used to provide the comparator for each kind of class . How can I replace the Generic ? in the declaration of my map to be sure that I have always the same Class type in key and value of my map ( comparators ) ? I want also to reduce the numbe... | How to Use Generics in a map of Comparator to avoid warnings |
Java : Lets say I have a class C that is doing some job . For that I need a little very simple helper class H ( e.g . representation of a pair or a 3-tuple ) . H is only needed in C.I would put H inside of C.Is putting H inside of C a good idea ? I do it to have it contained and at the place I think it should be and no... | OOP design of little helper classes |
Java : I have a Spring Boot application , which runs in an Apache Tomcat server . In application.yaml I have , among others , following entries : The application is deployed to Tomcat from within IntelliJ Idea so I can debug it.I start Tomcat using the following command : However , after Istart Tomcat using the above s... | How to make sure that environment variable placeholders are substituted in a Spring Boot application running in Apache Tomcat ? |
Java : I browsed some JAVA code made by Google , and I found the ImmutableSet : http : //google-collections.googlecode.com/svn/trunk/javadoc/com/google/common/collect/ImmutableSet.htmlThey implemented the of ( ) method with several other ways : I checked the implementation which is here : https : //code.google.com/p/go... | Equivalient method overload why necessary ? |
Java : First time I use Regex statement.I have java regex statement , which split String by pattern with list of some characters.output of above code is like ( 018020000304050.12500 ) Actually I want output like this , ( `` F '' , `` 01 '' , `` T '' , `` 8 '' , `` B '' , `` 02 '' , `` S '' , `` 00003 '' , `` H '' , `` ... | How to get list of pattern string and matcher string in java regex |
Java : I need some understanding from you expertsThis Program does not go to catch block ( as Heap is full , but I want to understand why ) But the below Program runs good , even after getting OOME : I am bit confused , after seeing different results for the same error OOME . Please guide <code> public class OOME_NotCa... | Why different behaviors for OOME while trying to catch it ? |
Java : I 've defined a class like this : This wo n't compile . I 'm not allowed to create the generic type T.How can I solve this ? Is there any good patterns to do this ? Can I solve this by using an abstract class instead of the interface ? Do I have to use reflection ? <code> public class MyClass < T implements MyIn... | How to create generic type ? |
Java : I need help to design java code for generating bit array for any given integer in following manner:23 should produce output as 1101011 ( min length array ) explaination : positions are given as 1 -2 4 -8 16 -32 ... .So 1101011 can be evaluated as : <code> 1*1 + 1*-2 + 0*4+ 1*-8 + 0*16 +1*-32 + 1*64 = 23 | Forming a pattern of bits from a integer |
Java : I 've failed to google this problem . Why would this line produce a compilation error.I 'm using java 7.The error is : <code> wrapper.doSmth ( wrapper.getCurrent ( ) ) ; public class App { Wrapper < ? > wrapper ; class Generic < T > { } class Wrapper < T > { Generic < T > current ; public void doSmth ( Generic <... | Code with generics wo n't compile |
Java : I want to calculate the volume of a sphere using a Java program . So , I used This formula gives the wrong answers it seems.Like Java program opt 4/3 , but if I change it to it gives me the correct answer . Does any one know what is going on ? <code> double result = 4/3*Math.PI*Math.pow ( r,3 ) ; double result= ... | java 2 different formula problems |
Java : Let 's take an example to make it easier . I build a list which the constructor takes an integer and a List < Integer > . My list will contains all the elements of the given list multiplied by the integer . My list does not store the new elements but compute them on the fly : Then we can call new MyList ( 3 , li... | How to return an object with multiple types |
Java : I am trying to make a void method that calculates average , but I would like to pass values to the method from the main method . Here is an example of what I am trying to do : The problem I 'm having is getting the values of multiple plants into the method . I 've tried using .get , loops , static , and many oth... | passing object values to methods |
Java : This is the snippet of code in Java language : Why does compiler ca n't see the second if statement considering the last option of the value ? It wo n't compile.Best regards <code> public void name ( ) { int value = 9 ; int o ; if ( value > 9 ) o = 5 ; if ( value < = 9 ) o = 8 ; System.out.println ( o ) ; } | Branching which ca n't be seen by compiler |
Java : Why in this snippet of code the cast ( MyClass ) o in line number 8 is necessary , despite the fact that the Client invokes a compare method with arguments which are instances of MyClass class ? When I modify the compare method in MyClass class to form like below : Then , the Client will produce the following re... | Why the cast is necessary in this case ? |
Java : Most questions about wildcards want to know why something sensible is rejected by the compiler . My question is the opposite . Why is the following program accepted by the compiler ? I tried to explain this from the Java Language Specification , but I have not found the answer . I had the impression from various... | Why is this assignment involving wildcards legal in Java ? |
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