invalid Definition Exception

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Intro error message

這篇介紹使用jackson反序列化時出現com.fasterxml.jackson.databind.Exc.invalidDefinitionException:(No Creators, Like Default Construct, Exist): Cannot Deserialize From Object Value (No Delegate- Or Property-Based Creator)。

Example Code

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List<Element> list = JSONUtils.parseJsonToInstanceList(jsonString, Element.class); -> 這句反序列化會有錯誤

public static <T> List<T> parseJsonToInstanceList(String jsonInput, Class<T> clazz) {
	try {
		return JSONUtils.readValue(jsonInput,
			TypeFactory.defaultInstance().constructCollectionType(ArrayList.class, clazz));
	} catch (IOException e) {
		LogUtils.parseError.error("jsonInput: " + jsonInput, e);
		throw new UncheckedIOException(e);
	}
}

Reason

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Element 物件少了沒有參數的建構子

Solution

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public class Element {

	public Element() {
		//加上這個建構子
	}
}