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https://github.com/artodeschini/javastreamutils


https://github.com/artodeschini/javastreamutils

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README 

        
# Java Stream Utils



This repository has exemples to use Java Stream and lambda



## requirements

 - Java 8+

 - IDE like as IntellJ or Eclipse



## 1 Operations



#### sample to create Stream instances



[Show Java Code](operations/CreateInstanceOfStream.java)



#### sample to use the method .forEach



[Show Java Code](operations/StreamForEachExemple.java)



#### sample to use the method .collect (trnasform stream in other collection etc)



[Show Java Code](operations/StreamCollectSample.java)



#### sample to use method .toArray (transform stream in array)



[Show Java Code](operations/StreamToArraySample.java)



### sample to use method .map to use a function to transform data



[Show Java Code](operations/StreamMapSample.java)



### sample to use method .flatMap to aggregate many list at one list



[Show Java Code](operations/StreamFlatMapSample.java)



### sample to use method .flatMap to aggregate many list at one list with Custon Object



[Show Java Code](operations/StreamFlatMapCustonObjectSample.java)



### sample to use the methods .count .distinct .sorted



[Show Java Code](operations/StreamDistinctCountSortSample.java)



### sample to use the method .filter with Predicate (result boolean)



[Show Java Code](operations/StreamFilterSample.java)



### sample to use the method reduce sum, max, min all elements



[Show Java Code](operations/StreamReduceSample.java)



### sample to use the methods .anyMatch allMatch and noneMatch



[Show Java Code](operations/StreamMatchSample.java)



### sample to use sum and avg terminal operation



[Show Java Code](terminal/StreamSumAvgSample.java)



## 2 Terminated Operations



### sample to use Collector.joining terminal operation -> concat all elements in on string



[Show Java Code](terminal/StreamJoiningSample.java)



### sample to use Collector.counting terminal operation count elements in stream



[Show Java Code](terminal/StremaCountSample.java)



### sample to use Collector.maxBy and Collector.minBy



[Show Java Code](terminal/StreamMinMaxSample.java)



### sample to use Collector.groupingBy age show all information



[Show Java Code](terminal/StreamGrupingBySample.java)



### sample to use Collector.groupingBy age show count occurrences



[Show Java Code](terminal/StreamGrupingBySample2.java)



### sample to use Collector.groupingBy age show show List of names 



[Show Java Code](terminal/StreamGrupingBySample3.java)



### sample to use Collector.partitioningBy with integrs



[Show Java Code](terminal/StreamPartitioningBySample.java)



### sample to use Collector.partitioningBy with strins



[Show Java Code](terminal/StreamPartitioningBySample2.java)



## 3 Numerical Stream IntStream LongStream and DoubleStream



### sample to use NumericStream range tangeClose count and ForEach methods



[Show Java Code](numeric/NumericStreamRangeRangeCloseCountForEach.java)



### sample to use NumericStream sum max min average methods



[Show Java Code](numeric/NumericStreamSumMaxMinAverageSample.java)



### sample to use NumericStream boxing and unboxing with mapToInt method



[Show Java Code](numeric/NumericSreamBoxingUnboxingMapToInt.java)



### sample to use NumericStream mapToObj mapToDoble mapToLong methods



[Show Java Code](numeric/NumericStreamMapToObjeMapToDoubleMapToLong.java)



## 3 Parallel Processing



Parallel strems in Java use the concept of multi-threading to process data concurrently and potentially improve the 

overral performance. The parallel stream framework automatically divides the worload into smaller task and assigns then

to multiple threads for parallel execution.



### Sequential Stream



* Process elements ina stream in a serial manner, one after another

* operations are executed in a single thread following the order of the stream

* suitable for small medium-sized data set or operations where the order of execution is omportant

* can be created by default when workin with streams



### Parallel Stream



* process elements in a stream concurrently, utilizing mutiple threads

* operations are divided into multiple tasks then ca be executed simultaneously on diffentes threads

* suitable for large data set or operations that can be performed independently

* create by converting a sequential stream to a parallel stream using the parallel() method



### When not use parallel stream



* small data sets

* sequential dependencies

* Non-thread-safe operation

* I/O-bound operations

* resource constrains

* order-sensitive operations



### sample to create a parallel stream



[Show Java Code](parallel/CreateParallelStream.java)



### sample to build a parallel stream



[Show Java Code](parallel/BuildParallelStreamPipeLine.java)



### sample to performance parallel stream x sequential stream



[Show Java Code](parallel/StreamPerformaceSample.java)



## 4 Others



### how to generate a stream for randon numbers integers or double



[Show Java Code](others/StreamNumberGenerator.java)



### how to sum with map or reduce



[Show Java Code](others/StreamSumCalculator.java)



### how to find duplicates values



[Show Java Code](others/StreamFindDuplicates.java)



### how to find duplicate form list/array ina custom object



[Show Java Code](others/StreamFindDuplicatesCustonObject.java)



### how to remove duplicates form list / array



[Show Java Code](others/StramRemoveDuplicatesByListOrArray.java)



### find second largest element to use skip



[Show Java Code](others/StreamSecondLargestElement.java)



### list all files in a directory



[Show Java Code](others/StreamFiles.java)



### filter stream with is not in another list



[Show Java Code](others/StreamFilterNotIn.java)