回答編集履歴
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追記
test
CHANGED
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@@ -4,18 +4,66 @@
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```
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7
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-
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7
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+
public static void main(String[] args) {
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9
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-
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9
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Map<Object, Object> omap = new HashMap<>();
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-
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omap.put("a", "9");
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-
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Object map = omap;
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-
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Map<? extends Object, ? extends Object> xmap = (Map<?, ?>) map;
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-
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System.out.println(xmap.get("a"));
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}
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```
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# map型じゃないケースを想定するとこうなる「
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```
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public static void main(String[] args) {
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Map<Object, Object> omap = new HashMap<>();
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omap.put("a", "9");
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// Map<Object,Object>#get を課程
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Object map = omap;
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// 以下 説明ソース
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Map<? extends Object, ? extends Object> xmap;
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if (map instanceof Map) {
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// 設定時
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xmap = (Map<?, ?>) map;
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} else {
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// 未設定時（任意の別のマップを設定するなりしてください）
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xmap = omap;
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}
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System.out.println(xmap);
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66
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}
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21
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```
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