Ozan Can Altiok created THRIFT-4476:
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Summary: Typecasting problem on list items
Key: THRIFT-4476
URL: https://issues.apache.org/jira/browse/THRIFT-4476
Project: Thrift
Issue Type: Bug
Affects Versions: 0.11.0
Reporter: Ozan Can Altiok
I was trying to add the following into a thrift interface file.
{{const list<double> timeCoefficients = [24, 60, 60, 1000, 1000, 1000]}}
With the definition given above the {{.thrift}} file compiled properly.
However, I noticed that in Python, the items in {{timeCoefficients}} are
considered to be integer although the list has been defined to include items of
{{double}} type. Then I modified the definition as given below to make sure all
the items are of type {{double}}.
{{const list<double> timeCoefficients = [24.0, 60.0, 60.0, 1000.0, 1000.0,
1000.0]}}
After the change, I ran into the following error during compilation.
{{[ERROR] .../TimeCoefficients.java:[402,48] error: no suitable method found
for add(int)}}
{{[ERROR] method Collection.add(Double) is not applicable}}
{{[ERROR] (argument mismatch; int cannot be converted to Double)}}
{{[ERROR] method List.add(Double) is not applicable}}
{{[ERROR] (argument mismatch; int cannot be converted to Double)}}
Next, I changed the line as follows and the compilation became successful.
{{const list<double> timeCoefficients = [24.1, 60.1, 60.1, 1000.1, 1000.1,
1000.1]}}
When I reviewed the generated Java source files, I discovered that
{{const list<double> timeCoefficients = [24, 60, 60, 1000, 1000, 1000]}}
compiles to
{{public static final java.util.List<java.lang.Double> timeCoefficients = new
java.util.ArrayList<java.lang.Double>();}}
{{ static {}}
{{ timeCoefficients.add((double)24);}}
{{ timeCoefficients.add((double)60);}}
{{ timeCoefficients.add((double)60);}}
{{ timeCoefficients.add((double)1000);}}
{{ timeCoefficients.add((double)1000);}}
{{ timeCoefficients.add((double)1000);}}
{{}}}
whilst
{{const list<double> timeCoefficients = [24.0, 60.0, 60.0, 1000.0, 1000.0,
1000.0]}}
compiles to
{{public static final java.util.List<java.lang.Double> timeCoefficients = new
java.util.ArrayList<java.lang.Double>();}}
{{ static { }}
{{ timeCoefficients.add(24);}}
{{ timeCoefficients.add(60);}}
{{ timeCoefficients.add(60);}}
{{ timeCoefficients.add(1000);}}
{{ timeCoefficients.add(1000);}}
{{ timeCoefficients.add(1000);}}
{{ }}}
which leads to an error.
When I modified this line as follows
{{const list<double> timeCoefficients = [24.1, 60.1, 60.1, 1000.1, 1000.1,
1000.1]}}
this line compiled to
{{public static final java.util.List<java.lang.Double> timeCoefficients = new
java.util.ArrayList<java.lang.Double>();}}
{{ static { }}
{{ timeCoefficients.add(24.1);}}
{{ timeCoefficients.add(60.1);}}
{{ timeCoefficients.add(60.1);}}
{{ timeCoefficients.add(1000.1);}}
{{ timeCoefficients.add(1000.1);}}
{{ timeCoefficients.add(1000.1);}}
{{ }}}
My guess is that, even if I put {{.0}} at the end of each numeric constant, on
the Java side, Thrift compiler considers them to be {{double}} and does no
typecasts. However, the {{.0}} s are getting lost somewhere and the items
become integers in the generated Java code. Thus, when it comes to populating
the array, Java cannot succeed. {{Double}} s cannot be unboxed to integer and
Java thinks {{int}} and {{Double}} are not related.
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