sort map groupingBy counting

Is there way to sort map by value inside this collector without creation a new stream?
Now it prints: AAS : 5 ABA : 195 ABC : 12 ABE : 52.
Desired: ABA : 195 ABE : 52 ...
getTrigraphStream(path) returns: HOW THE TRA GRI ONC GRI ONC INS WHE INS WHE

 public Map<String, Long> getTrigraphStatisticsMapAlphabet(String path) {

    return getTrigraphStream(path)

       .collect(groupingByConcurrent(Function.identity(),

           ConcurrentSkipListMap::new, counting()));

    }

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

asked Nov 20 '18 at 19:12

a_chubenko

4615

add a comment |

 public Map<String, Long> getTrigraphStatisticsMapAlphabet(String path) {

    return getTrigraphStream(path)

       .collect(groupingByConcurrent(Function.identity(),

           ConcurrentSkipListMap::new, counting()));

    }

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

asked Nov 20 '18 at 19:12

a_chubenko

4615

add a comment |

 public Map<String, Long> getTrigraphStatisticsMapAlphabet(String path) {

    return getTrigraphStream(path)

       .collect(groupingByConcurrent(Function.identity(),

           ConcurrentSkipListMap::new, counting()));

    }

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

asked Nov 20 '18 at 19:12

a_chubenko

4615

 public Map<String, Long> getTrigraphStatisticsMapAlphabet(String path) {

    return getTrigraphStream(path)

       .collect(groupingByConcurrent(Function.identity(),

           ConcurrentSkipListMap::new, counting()));

    }

sorting java-8 java-stream counting collectors

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

asked Nov 20 '18 at 19:12

a_chubenko

4615

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

asked Nov 20 '18 at 19:12

a_chubenko

4615

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

edited Nov 20 '18 at 19:58

Stefan Zobel

2,44031828

asked Nov 20 '18 at 19:12

a_chubenko

4615

asked Nov 20 '18 at 19:12

a_chubenko

4615

asked Nov 20 '18 at 19:12

a_chubenko

4615

add a comment |

1 Answer
1

active

oldest

votes

Is there way to sort map by value inside this collector without
creation a new stream?

The answer is No. You can only sort by the value of the grouping after you've finished grouping.

Options:

You'll need to invoke the stream() method after grouping and sort by
value then collect to a map.

use collectingAndThen with a finishing function to do the sorting
and then collect to map.

i.e.

return getTrigraphStream(path)

       .collect(collectingAndThen(groupingByConcurrent(Function.identity(), counting()),

                  map -> map.entrySet().stream().sorted(....).collect(...)));

By the way, what's the problem with creating a new stream? it's a cheap operation.

edited Nov 21 '18 at 8:59

answered Nov 20 '18 at 20:35

Aomine

42k74071

or use a SortedMap maybe?

– nullpointer
Nov 21 '18 at 0:37

1

In this operation, there is no need to use a ConcurrentSkipListMap.

– Holger
Nov 21 '18 at 8:03

@nullpointer that sorts the map by keys as opposed to values I believe.

– Aomine
Nov 21 '18 at 9:06

add a comment |

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1 Answer
1

active

oldest

votes

1 Answer
1

active

oldest

votes

Is there way to sort map by value inside this collector without
creation a new stream?

The answer is No. You can only sort by the value of the grouping after you've finished grouping.

Options:

You'll need to invoke the stream() method after grouping and sort by
value then collect to a map.

use collectingAndThen with a finishing function to do the sorting
and then collect to map.

i.e.

return getTrigraphStream(path)

       .collect(collectingAndThen(groupingByConcurrent(Function.identity(), counting()),

                  map -> map.entrySet().stream().sorted(....).collect(...)));

By the way, what's the problem with creating a new stream? it's a cheap operation.

edited Nov 21 '18 at 8:59

answered Nov 20 '18 at 20:35

Aomine

42k74071

or use a SortedMap maybe?

– nullpointer
Nov 21 '18 at 0:37

1

In this operation, there is no need to use a ConcurrentSkipListMap.

– Holger
Nov 21 '18 at 8:03

@nullpointer that sorts the map by keys as opposed to values I believe.

– Aomine
Nov 21 '18 at 9:06

add a comment |

Is there way to sort map by value inside this collector without
creation a new stream?

The answer is No. You can only sort by the value of the grouping after you've finished grouping.

Options:

You'll need to invoke the stream() method after grouping and sort by
value then collect to a map.

use collectingAndThen with a finishing function to do the sorting
and then collect to map.

i.e.

return getTrigraphStream(path)

       .collect(collectingAndThen(groupingByConcurrent(Function.identity(), counting()),

                  map -> map.entrySet().stream().sorted(....).collect(...)));

By the way, what's the problem with creating a new stream? it's a cheap operation.

edited Nov 21 '18 at 8:59

answered Nov 20 '18 at 20:35

Aomine

42k74071

or use a SortedMap maybe?

– nullpointer
Nov 21 '18 at 0:37

1

In this operation, there is no need to use a ConcurrentSkipListMap.

– Holger
Nov 21 '18 at 8:03

@nullpointer that sorts the map by keys as opposed to values I believe.

– Aomine
Nov 21 '18 at 9:06

add a comment |

Is there way to sort map by value inside this collector without
creation a new stream?

The answer is No. You can only sort by the value of the grouping after you've finished grouping.

Options:

You'll need to invoke the stream() method after grouping and sort by
value then collect to a map.

use collectingAndThen with a finishing function to do the sorting
and then collect to map.

i.e.

return getTrigraphStream(path)

       .collect(collectingAndThen(groupingByConcurrent(Function.identity(), counting()),

                  map -> map.entrySet().stream().sorted(....).collect(...)));

By the way, what's the problem with creating a new stream? it's a cheap operation.

edited Nov 21 '18 at 8:59

answered Nov 20 '18 at 20:35

Aomine

42k74071

Is there way to sort map by value inside this collector without
creation a new stream?

The answer is No. You can only sort by the value of the grouping after you've finished grouping.

Options:

You'll need to invoke the stream() method after grouping and sort by
value then collect to a map.

use collectingAndThen with a finishing function to do the sorting
and then collect to map.

i.e.

return getTrigraphStream(path)

       .collect(collectingAndThen(groupingByConcurrent(Function.identity(), counting()),

                  map -> map.entrySet().stream().sorted(....).collect(...)));

By the way, what's the problem with creating a new stream? it's a cheap operation.

edited Nov 21 '18 at 8:59

answered Nov 20 '18 at 20:35

Aomine

42k74071

edited Nov 21 '18 at 8:59

answered Nov 20 '18 at 20:35

Aomine

42k74071

answered Nov 20 '18 at 20:35

Aomine

42k74071

answered Nov 20 '18 at 20:35

Aomine

42k74071

or use a SortedMap maybe?

– nullpointer
Nov 21 '18 at 0:37

1

In this operation, there is no need to use a ConcurrentSkipListMap.

– Holger
Nov 21 '18 at 8:03

@nullpointer that sorts the map by keys as opposed to values I believe.

– Aomine
Nov 21 '18 at 9:06

add a comment |

or use a SortedMap maybe?

– nullpointer
Nov 21 '18 at 0:37

1

In this operation, there is no need to use a ConcurrentSkipListMap.

– Holger
Nov 21 '18 at 8:03

@nullpointer that sorts the map by keys as opposed to values I believe.

– Aomine
Nov 21 '18 at 9:06

or use a SortedMap maybe?

– nullpointer
Nov 21 '18 at 0:37

In this operation, there is no need to use a ConcurrentSkipListMap.

– Holger
Nov 21 '18 at 8:03

@nullpointer that sorts the map by keys as opposed to values I believe.

– Aomine
Nov 21 '18 at 9:06

add a comment |

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