[英]How can I sort a Map through the keyset?
我想以不斷增長的方式通過其鍵集元素對地圖進行排序。 聯接類型為innerJoin。 我有以下代碼:
Comparator<Tuple2<String, Integer>> comparator = Comparator.comparing((Function<Tuple2<String, Integer>, String>) Tuple2::get0).thenComparing(Tuple2::get1);
Map<Tuple2<String, Integer>, LongSummaryStatistics> grouped = join.stream()
.collect(groupingBy(t -> Tuples.of(t.get1().getCNation(), t.get4().getDYear()), () -> new TreeMap<>(comparator), summarizingLong(t->t.get0().getLoRevenue()-t.get0().getLoSupplycost())));
grouped.forEach((k, v) -> {
System.out.format("%-32s, %,d%n", k, v.getSum());
});
返回結果:
Tuple2Impl {ARGENTINA, 1992} , 9.671.947.837
Tuple2Impl {ARGENTINA, 1993} , 10.047.205.160
Tuple2Impl {ARGENTINA, 1994} , 10.141.821.441
Tuple2Impl {BRAZIL, 1992} , 9.241.877.689
Tuple2Impl {BRAZIL, 1993} , 9.057.962.411
Tuple2Impl {BRAZIL, 1994} , 9.303.902.867
Tuple2Impl {CANADA, 1992} , 9.746.312.266
Tuple2Impl {CANADA, 1993} , 9.754.277.048
Tuple2Impl {CANADA, 1994} , 10.069.331.565
...
我想得到以下結果:
Tuple2Impl {ARGENTINA, 1992} , 9.671.947.837
Tuple2Impl {BRAZIL, 1992} , 9.241.877.689
Tuple2Impl {CANADA, 1992} , 9.746.312.266
Tuple2Impl {ARGENTINA, 1993} , 10.047.205.160
Tuple2Impl {BRAZIL, 1993} , 9.057.962.411
Tuple2Impl {CANADA, 1993} , 9.754.277.048
Tuple2Impl {ARGENTINA, 1994} , 10.141.821.441
Tuple2Impl {BRAZIL, 1994} , 9.303.902.867
Tuple2Impl {CANADA, 1994} , 10.069.331.565
...
看來您想按年份再按國家訂購。
Comparator<Tuple2<String, Integer>> comparator =
Comparator.comparing((Function<Tuple2<String, Integer>, Integer>) Tuple2::get1)
.thenComparing(Tuple2::get0);
編輯請注意,我用get1
然后get0
,而你的代碼是使用get0
然后get1
。
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