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Add default capacity to EnumTypeAdapter maps #2959

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Add default capacity to EnumTypeAdapter maps #2959

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13 changes: 9 additions & 4 deletions gson/src/main/java/com/google/gson/internal/bind/EnumTypeAdapter.java
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Original file line number Diff line number Diff line change
Expand Up @@ -50,9 +50,9 @@ public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> typeToken) {
}
};

private final Map<String, T> nameToConstant = new HashMap<>();
private final Map<String, T> stringToConstant = new HashMap<>();
private final Map<T, String> constantToName = new HashMap<>();
private final Map<String, T> nameToConstant;
private final Map<String, T> stringToConstant;
private final Map<T, String> constantToName;

private EnumTypeAdapter(Class<T> classOfT) {
try {
Expand All @@ -69,7 +69,12 @@ private EnumTypeAdapter(Class<T> classOfT) {

// Trim the array to the new length. Every enum type can be expected to have at least
// one declared field which is not an enum constant, namely the implicit $VALUES array
fields = Arrays.copyOf(fields, constantCount);
fields = (constantCount == fields.length) ? fields : Arrays.copyOf(fields, constantCount);

nameToConstant = new HashMap<>(constantCount, 1F);
stringToConstant = new HashMap<>(constantCount, 1F);
// Don't use `EnumMap` here; that can break when using ProGuard or R8
constantToName = new HashMap<>(constantCount, 1F);
Comment on lines +74 to +77
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@Marcono1234 Marcono1234 Dec 8, 2025 •
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Not sure if 'load factor' 1F here could decrease performance (and if that would be noticeable)? See HashMap documentation:

As a general rule, the default load factor (.75) offers a good tradeoff between time and space costs. Higher values decrease the space overhead but increase the lookup cost (reflected in most of the operations of the HashMap class, including get and put).

If you want feel free to keep it like this for now and wait for the feedback from the Gson project members.


AccessibleObject.setAccessible(fields, true);

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