snippets.get-type-arguments.txt Maven / Gradle / Ivy

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        Map resolvedTypes = new LinkedHashMap();
        Type type = childClass;
        // start walking up the inheritance hierarchy until we hit baseClass
        while (! getClass(type).equals(baseClass)) {
            if (type instanceof Class) {
                // there is no useful information for us in raw types, so just keep going.
                type = ((Class) type).getGenericSuperclass();
            }
            else {
                ParameterizedType parameterizedType = (ParameterizedType) type;
                Class rawType = (Class) parameterizedType.getRawType();

                Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
                TypeVariable[] typeParameters = rawType.getTypeParameters();
                for (int i = 0; i < actualTypeArguments.length; i++) {
                    resolvedTypes.put(typeParameters[i], actualTypeArguments[i]);
                }

                if (!rawType.equals(baseClass)) {
                    type = rawType.getGenericSuperclass();
                }
            }
        }

        // finally, for each actual type argument provided to baseClass, determine (if possible)
        // the raw class for that type argument.
        Type[] actualTypeArguments;
        if (type instanceof Class) {
            actualTypeArguments = ((Class) type).getTypeParameters();
        }
        else {
            actualTypeArguments = ((ParameterizedType) type).getActualTypeArguments();
        }
        List> typeArgumentsAsClasses = new ArrayList>();
        // resolve types by chasing down type variables.
        for (Type baseType: actualTypeArguments) {
            while (resolvedTypes.containsKey(baseType)) {
                baseType = resolvedTypes.get(baseType);
            }
            typeArgumentsAsClasses.add(getClass(baseType));
        }
        return typeArgumentsAsClasses;