java-stream Archives - Page 3 of 5

Why does Stream not implement Iterable?

In Java 8 we have the class Stream<T>, which curiously have a method Iterator<T> iterator() So you would expect it to implement interface ...

May 17, 2022
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Java 8 Streams: multiple filters vs. complex condition

Sometimes you want to filter a Stream with more than one condition: myList.stream().filter(x -> x.size() > 10).filter(x -> x.isCool()) ... or you could ...

May 17, 2022
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What is difference between Collection.stream().forEach() and Collection.forEach()?

I understand that with .stream(), I can use chain operations like .filter() or use parallel stream. But what is difference between them if ...

May 15, 2022
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Java 8 lambdas, Function.identity() or t->t

I have a question regarding the usage of the Function.identity() method. Imagine the following code: Arrays.asList("a", "b", "c") .stream() .map(Function.identity()) // <- This, ...

May 15, 2022
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Ignore duplicates when producing map using streams

Map<String, String> phoneBook = people.stream() .collect(toMap(Person::getName, Person::getAddress)); I get java.lang.IllegalStateException: Duplicate key when a duplicated element is found. Is it possible to ignore ...

May 12, 2022
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How can I throw CHECKED exceptions from inside Java 8 streams?

How can I throw CHECKED exceptions from inside Java 8 streams/lambdas? In other words, I want to make code like this compile: public ...

May 12, 2022
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How to sum a list of integers with java streams?

I want to sum a list of Integers. It works as follows, but the syntax does not feel right. Could the code be ...

May 5, 2022
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Custom thread pool in Java 8 parallel stream

Is it possible to specify a custom thread pool for Java 8 parallel stream? I can not find it anywhere. Imagine that I ...

May 5, 2022
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NullPointerException in Collectors.toMap with null entry values

Collectors.toMap throws a NullPointerException if one of the values is null. I don’t understand this behaviour, maps can contain null pointers as value ...

May 4, 2022
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Is there a concise way to iterate over a stream with indices in Java 8?

Is there a concise way to iterate over a stream whilst having access to the index in the stream? String...

May 4, 2022
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