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Enumの使用例 #4

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Enumの使用例 #4

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26 changes: 26 additions & 0 deletions java/enum/enumMember.java
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// かっこいいEnumの活用

public enum FileType {
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@pollseed pollseed Jan 27, 2016

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使う側の話だけど、共通化させて、どのクラスからも参照しやすいようにディレクトリ構成にして無駄なコードを作成しないようにエンジニアに教えてあげるようにするといいと思う。

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@Gaddict Gaddict Jan 27, 2016

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どのクラスからも参照しやすいようにディレクトリ構成にして

ここがちょっとよくわからないんだけど、
ディレクトリ構成ってenumの中の構造のこと？

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@pollseed pollseed Jan 27, 2016

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インナークラスにenumを突っ込んで使うわけではなければって意味

例えば、

class Hoge {
  enum Fuga {
  }
}

みたいに使うなら特に気にすることはないかな
今回はどういう状況で使ってるのかわからないからどっちとも言えないけど

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@Gaddict Gaddict Jan 27, 2016

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なるほど

SystemCd("sys", 10),
DcfDrCd("dcf", 6);
public final String paramName;
public final int cdLength;
private FileType(final String paramName, final int cdLength) {
this.paramName = paramName;
this.cdLength = cdLength;
}
public static Optional<FileType> paramNameOf(final String paramName) {
return Stream.of(values()).filter(f -> f.paramName.equals(paramName)).findAny();
}
}

// enumはこんなに拡張できる（Javaのみらしい）
// 以下サンプル

// fileTypeで与えられた文字列が定義されてるかどうかを一撃で判定できる
final String fileType = "hoge";
if (!FileType.paramNameOf(fileType).isPresent())

// enumの各項目に紐づく値を取れる
FileType filetype = FileType.SystemCd;
fileType.cdLength;