javautils: A Java repository from hadasbro

Java Utils - zero dependency library with useful utils

Use this class if you need to do some operations on Java objects, collections, or if you need to generate objects etc.

~~Uses Models Projector(https://github.com/glaures/modelprojector)~~ [removed in ver.1.0.2]
~~Apache Commonts (https://commons.apache.org/)~~ [removed in ver.1.0.2]
jUnit (https://junit.org/)

Installation

Install from Maven Central Repository.

<dependency>
  <groupId>com.github.hadasbro</groupId>
  <artifactId>javautils</artifactId>
  <version>1.0.1</version>
</dependency>

Overview

Library contains some methods to

Handle collections of elements
Print and stringify object of any kind.
~~Some object utils e.g. POJO < - > DTO converter.~~
Some additional methods, e.g. Object Coalesce, wrapper for CompletionException, array element exists checker and more

Usage

Code has been splitted for some subclasses as below.

Example objects (see classes below)

Game gameA = null;
User userA = null;
Game gameB = new Game("Game 1", "game1", "category 1");
Game gameC = new Game("Game 2", "game2", "category 2");
Game gameD = new Game("Game 3", "game3", "category 1");
Game gameE = new Game("Game 4", "game4", "category 3");


List<Game> gamesCollection = new LinkedList<>(){{
    add(gameB); add(gameC); add(gameD); add(gameE);
}};

List<Game> gamesCollection2 = new LinkedList<>(){{
    add(gameB);
}};

List<Game> gamesCollection3 = new LinkedList<>(){{
    add(gameC); add(gameD);
}};

List<Game> gamesCollection4 = new LinkedList<>(){{
    add(gameE);
}};

CollectionUtils - methods usefult for handling collections

a) CollectionUtils::collGroupper - group collection of objects by object's method value / by property

signature

<T extends EntityTag, S> Map<S, Set<T>> collGroupper<T extends EntityTag, S> Map<S, Set<T>> collGroupper(Collection<T> collection,Collector<? super T, ?, Map<S,Set<T>>> collector)

usage

Map<String, Set<Game>> grouppedByCategory = CollectionUtils.collGroupper(
        gamesCollection,
        Game::getCategory
);

result

  {category 3=[Game{name='Game 4', gameTag='game4', category='category 3'}],category 2=[Game{name='Game 2', gameTag='game2', category='category 2'}],category 1=[Game{name='Game 1', gameTag='game1', category='category 1'},Game{name='Game 3', gameTag='game3', category='category 1'}]}

b) CollectionUtils.collGroupperFlatter - group collection of objects by object's method value / by property and flat to object value / property

signature

<T extends EntityTag, S, R> Map<S, Set<R>> collGroupperFlatter(gamesCollection, Game::getCategory, Game::getName);

usage

Map<String, Set<String>> gameNameByCategory = CollectionUtils.collGroupperFlatter(
        gamesCollection,
        Game::getCategory,
        Game::getName
);

result

  {category 3=[Game 4], category 2=[Game 2], category 1=[Game 1, Game 3]}

c) CollectionUtils.advancedTransFilter - collection's filter and transformer

signature

Collection<T> advancedTransFilter(Collection<S> collection, Predicate<S> filter,Function<S,T> transformer)

usage

Collection<Game> gameListNewCategory = CollectionUtils.advancedTransFilter(
        gamesCollection,
        g -> g.getCategory().equals("category 1"),
        g -> {
            g.setCategory("New category");
            return g;
        }
);

result

   [Game{name='Game 1', gameTag='game1', category='New category'}, Game{name='Game 3', gameTag='game3', category='New category'}]

d) CollectionUtils::transformCollection - transform collection using multiple transformers

signature

<T> Collection<T> transformCollection(Collection<T> collection,UnaryOperator<T> ...transformers)

usage

Collection<Game> transformedCollection = CollectionUtils.transformCollection(
        gamesCollection,
        g -> {
            g.setCategory("New category");
            return g;
        },
        g -> {
            g.setName(g.getName().toUpperCase());
            return g;
        },
        g -> {
            g.setGameTag(g.getGameTag().toLowerCase());
            return g;
        }
);

result

  [Game{name='GAME 1', gameTag='game1', category='New category'},Game{name='GAME 2', gameTag='game2', category='New category'},Game{name='GAME 3', gameTag='game3', category='New category'},Game{name='GAME 4', gameTag='game4', category='New category'}]

e) CollectionUtils.findAll - search all elements in collection by predicate

signature

<T> ArrayList<T> findAll(Collection<T> collection, Predicate<T> filter)

usage

ArrayList<Game> gamesFromCategory1 = CollectionUtils.findAll(
        gamesCollection, game -> game.getCategory().equals("New category")
);

result

  [Game{name='GAME 1', gameTag='game1', category='New category'},Game{name='GAME 2', gameTag='game2', category='New category'},Game{name='GAME 3', gameTag='game3', category='New category'},Game{name='GAME 4', gameTag='game4', category='New category'}]

f) CollectionUtils.getRandomElement - get element by index or random if index is out of bound

signature

<T> T getRandomElement(List<T> list, int index)

usage

Game randomGame = CollectionUtils.getRandomElement(gamesCollection, 5);

result

  Game{name='GAME 2', gameTag='game2', category='New category'}

g) CollectionUtils::getFirstFromCollection - get first element from collection

signature

<E> E getFirstFromCollection(Collection<E> collection)

usage

Game firstGame = CollectionUtils.getFirstFromCollection(gamesCollection);

result

  Game{name='GAME 1', gameTag='game1', category='New category'}

h) CollectionUtils::objGenerateSet + CollectionUtils::objGenerate - generate Set/List of objects by supplier

signature

<T> Set<T> objGenerateSet(Integer n, Function<Integer, T> s)
<T> ArrayList<T> objGenerate(Integer n, Function<Integer, T> s)

usage

Set<Game> my5Games = CollectionUtils.objGenerateSet(
        5, i -> new Game("Game " + i, "tag" + i, "category")
);

ArrayList<Game> myAnother5Games = CollectionUtils.objGenerate(
        5, i -> new Game("Game " + i, "tag" + i, "category")
);

result

  [Game{name='Game 0', gameTag='tag0', category='category'},Game{name='Game 1', gameTag='tag1', category='category'}, Game{name='Game 2', gameTag='tag2', category='category'},Game{name='Game 3', gameTag='tag3', category='category'}, Game{name='Game 4', gameTag='tag4', category='category'}]
  [Game{name='Game 0', gameTag='tag0', category='category'},Game{name='Game 1', gameTag='tag1', category='category'},Game{name='Game 2', gameTag='tag2', category='category'},Game{name='Game 3', gameTag='tag3', category='category'},Game{name='Game 4', gameTag='tag4', category='category'}]

i) CollectionUtils::listsCombiner

signature

<T> List<T> listsCombiner(List<? extends T>... lists)

usage

List<Game> combinedList = CollectionUtils.listsCombiner(gamesCollection2, gamesCollection3, gamesCollection4);

result

  [Game{name='GAME 1', gameTag='game1', category='New category'},Game{name='GAME 2', gameTag='game2', category='New category'},Game{name='GAME 3', gameTag='game3', category='New category'},Game{name='GAME 4', gameTag='game4', category='New category'}]

j) CollectionUtils::anyOkFromCollection, CollectionUtils::allNotOkFromCollection, CollectionUtils::allOkFromCollection

signatures

<T> boolean allOkFromCollection(Collection<T> collection, Predicate<? super T> condition)
<T> boolean allNotOkFromCollection(Collection<T> collection, Predicate<? super T> condition)
<T> boolean anyOkFromCollection(Collection<T> collection, Predicate<? super T> condition)

usage

boolean collectionContainsGameCategory1 = CollectionUtils.anyOkFromCollection(
      gamesCollection2,
      game -> game.getCategory().equals("category 1")
);

boolean collectionNotContainsGameCategory1 = CollectionUtils.allNotOkFromCollection(
        gamesCollection2,
        game -> game.getCategory().equals("category 1")
);

boolean collectionContainsOnlyGameCategory1 = CollectionUtils.allOkFromCollection(
        gamesCollection2,
        game -> game.getCategory().equals("category 1")
);

result
```
   false, true, false
```

ObjectUtils - operations on objects. ~~a) ObjectUtils::convertPojoToDto - convert POJO - > DTO~~

~~signatures~~

<T extends DtoObject, S extends EntityTag> T convertPojoToDto(Class<T> targetClass, S post)
<T extends DtoObject, S extends EntityTag> List<T> convertPojoToDto(Class<T> targetClass, Collection<S> post)

~~usage~~

    // single object conversion
    GameDto gameDtoResult = ObjectUtils.convertPojoToDto(GameDto.class, gameB);
    
    // collection of POJOs
    List<GameDto> gameDtoResults = ObjectUtils.convertPojoToDto(GameDto.class, new ArrayList<Game>(){{
        add(gameB);
        add(gameC);
        add(gameD);
    }});
    ```

~~result~~

   GameDto object ( GameDto{name='Game 1'} )
   GameDto objects ( [GameDto{name='Game 1'}, GameDto{name='Game 2'}, GameDto{name='Game 3'}] )

~~b) ObjectUtils::convert - convert DTO -> POJO~~

~~signature~~

<T, S> T convert(Class<T> targetClass, S post)

~~usage~~

Game game = ObjectUtils.convert(Game.class, gameDtoResult);

~~result~~
```
   Game object ( Game{name='Game 1'} )
```

~~see more( https://github.com/glaures/modelprojector )~~

ThreadUtils - multithread programming utils. a) ThreadUtils::excToCompletableExc - wrap CompletionException exceptions in CompletableFuture

signature

CompletionException excToCompletableExc(Throwable tex)

usage

/*
 * wrap custom exception in completable future and throw
 * to be able to handle this exception later (unwrap and handle)
 */
CompletableFuture.allOf(
        CompletableFuture.supplyAsync(() -> {
            throw ThreadUtils.excToCompletableExc(new CustomException("Example exception"));
        })
)

.handle((res, ex) -> {

    if (ex != null && ex.getCause() instanceof CustomException) {
        return (CustomException) ex.getCause();
    }
    return null;

});

result

  you can handle CustomException in .handle() method

General Utils - other useful methods.

Utils::coalesce

Utils.coalesce(gameA, userA, gameB, gameC)

Utils.coalesce(
        () -> null,
        () -> gameB,
        () -> gameC
);

// Game{name='Game 1', gameTag='game1', category='category 1'}
// Game{name='Game 1', gameTag='game1', category='category 1'}
// first not null element

Utils::rand

int rand1 = Utils.rand(0, 100); // random number from 0 to 100
int rand2 = Utils.rand(115, 200); // random number from 115 to 200

Utils::getRandString

String randString = Utils.getRandString(32);
// random string 32 characters (e.g. ppS4NlSGnSTo7HuwPkvIV14HOBUPKdXh)

Utils::arrayInclude

String strings[] = {"abc", "def", "ghi"};
Utils.arrayInclude(strings, "def"); // true
Utils.arrayInclude(strings, "defghi"); // false

Object stringifer - var_dump / object printer.

Interface

interface Printeable {
    default String stringify() {
        return ToStringBuilder.reflectionToString(this, new ObjectStringifer.PrintToStringStyle());
    }

    default String deepStringify() {
        return (new ObjectStringifer.DeepObjectPrinter()).toString(this);
    }
}

Usage: Implement this interface if you want your object/class to be stringifeable.

Example:

public class Game implements Printeable {} 

Game game = new Game("Game 1", "game1", "category 1");

String gameStr1 = gameB.stringify();
// [name=Game 1,gameTag=game1,category=category 1]

String gameStr2 =  game.deepStringify());
// org.bitbucket.javautils.test.classes.Game[name=Game 1,gameTag=game1,category=category 1][]

// object printers
game.print();
game.deepPrint();

Classes used in examples above

see source code, package test.classes

Authors

Slawomir Hadas - author - Github

hadasbro/javautils

Installation

Overview

Usage

Authors