CODEWITHSUNDEEP
javagenerics
Surya
Surya

Reputation: 4992

java generics: getting class of a class with generic parameters

I am curious how to make this work 

 Class<Map<String,String>> food = Map.class;

That obviously doesn't work. I would want something like this 

 Class<Map<String,String>> food = Map<String,String>.class;

but this seems like not a valid java sytax.

How can make this work?

EDIT: The reason I want this is because I have a method like this

   protected <ConfigType> ConfigValue<ConfigType> getSectionConfig(String name, Class<ConfigType> configType) {
        return config.getConfig(name);
    }

I would like to call this as so 

ConfigValue<Map<String,Object>> config = getSectionConfig("blah", Map<String,Object>.class>);
Map<String,Value> val = config.value();

Upvotes: 19

Views: 14615

Answers (3)

Andrei Hryshanovich
Andrei Hryshanovich

Reputation: 21

Not sure but may be ParameterizedTypeReference class can help you?

private static final ParameterizedTypeReference<Map<String, Object>> YOUR_TYPE_NAME = new ParameterizedTypeReference<Map<String, Object>>() {};

Upvotes: 0

ZhongYu
ZhongYu

Reputation: 19702

Do a brute cast

    Class<Map<String,String>> clazz = 
             (Class<Map<String,String>>)(Class)Map.class;

this is not theoretically correct, but it is not our fault. We need such hacks some times.

Upvotes: 19

rgettman
rgettman

Reputation: 178333

According to the JLS, Section 15.8.2, you can't do that, because:

The type of C.class, where C is the name of a class, interface, or array type (§4.3), is Class<C>.

The closest you can come is

Class<Map> food = Map.class;

Upvotes: 4

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