回答編集履歴

2

リンクの追加

2019/11/26 09:42

投稿

LouiS0616
LouiS0616

スコア35658

test CHANGED
@@ -95,3 +95,17 @@
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  [1, 2, 3, 4, 5, 6, 7, 8, 9]
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  ```
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+
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+ 参考
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+ ---
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+ 安定の公式リファレンス。
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+ - [Stream (Java SE 13 & JDK 13 )](https://docs.oracle.com/javase/jp/13/docs/api/java.base/java/util/stream/Stream.html)
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+ - [IntStream (Java SE 13 & JDK 13 )](https://docs.oracle.com/javase/jp/13/docs/api/java.base/java/util/stream/IntStream.html)

1

追記

2019/11/26 09:42

投稿

LouiS0616
LouiS0616

スコア35658

test CHANGED
@@ -45,3 +45,53 @@
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  [1, 2, 3, 4, 5, 6]
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  ```
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+ 案2
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+
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+ ---
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+ ちょっと読みづらいですけど、任意個数の結合にも対応できる例。
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+ ```Java
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+ import java.util.*;
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+ import java.util.stream.*;
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+ class Main {
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+ static int[] concat(int[]... arrs) {
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+ return Stream.of(arrs).flatMapToInt(IntStream::of).toArray();
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+ }
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+ public static void main(String[] args) {
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+ System.out.println(Arrays.toString(
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+ concat(new int[]{1, 2, 3}, new int[]{4, 5, 6}, new int[]{7, 8, 9})
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+ ));
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+ }
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+ }
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+ ```
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+ **実行結果** [Wandbox](https://wandbox.org/permlink/mdql7gB4guBIgUvl)
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+ ```
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+ [1, 2, 3, 4, 5, 6, 7, 8, 9]
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+ ```