bson/src/main/org/bson/BasicBSONObject.java
public double getDouble(final String key) {
        Object foo = get(key);
        return ((Number) foo).doubleValue();
    }
public double getDouble(final String key) {
        Object foo = get(key);
        return ((Number) foo).doubleValue();
    }
Returns the value of a field as a {@code double}.

@param key the field to return
@return the field value