Gson LinkedTreeMap

work

Problem

Given a Gson object with format LinkedTreeMap<String, String>, e.g.:

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LinkedTreeMap<String, String> misc = {
  misc1: misc_site,
  misc2: misc_sector,
  misc3: null,
  misc4: null
}

I got the HashMap with

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{
  misc: null
}
and
{}

And pass case assertThat(misc).isNull(); is what I expected. Unfortunately both were deleted not Null.
I try to transform the type into HashTable but got:

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ERROR: com.google.gson.internal.LinkedTreeMap cannot be cast to java.util.Hashtable

Solution

Construct an Iterator to get each value in map in sequence (LinkedTreeMap has already did it).

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Iterator it = misc.keySet().iterator();
Integer cnt = 0;
while (it.hasNext()) {
    String key = (String) it.next();
    if (misc.get(key) != null) cnt++;
}
assertThat(cnt).isEqualTo(0);

不怎么好看不过能用。。

Ref: Gson解析时对于不确定泛型的处理