object

问题 I have a sample class, say Country : class Country { public String name; public int population; public Flag flag; ... } I have this Flag class defined somewhere else class Flag { String id; int pixel; ... } Now I create a separate comparator DefaultFlagRankingComparator() that can sort Flag by id. How can I sort a list of Country by Flag id, using this DefaultFlagRankingComparator()? 回答1: You can invoke the compare method of the Comparator with the flag field of each country.

问题 I am curious how is the Object class implemented. For example a method hashCode() or wait() How is the internal state represented. For instance, an instrinsic lock or the data structure for storing threads that called object's wait(). In order to find these out, I have downloaded a source of OpenJDK and started to dig in. First thing, I came across was \openjdksrc\jdk\src\share\native\java\lang\Object.c file, containing, among others: static JNINativeMethod methods[] = { {"hashCode", "()I",

问题 I am curious how is the Object class implemented. For example a method hashCode() or wait() How is the internal state represented. For instance, an instrinsic lock or the data structure for storing threads that called object's wait(). In order to find these out, I have downloaded a source of OpenJDK and started to dig in. First thing, I came across was \openjdksrc\jdk\src\share\native\java\lang\Object.c file, containing, among others: static JNINativeMethod methods[] = { {"hashCode", "()I",

问题 Is class an object in object oriented language? How are Class methods accessed by just name of the class.method name ? (internal working). Is this same as a object.method ? And If the Class is same as object (belong to object class which is super class of every thing in OO) and we instantiate it (make object of it), can we make instance of an instance of an class other than Object class. (Mainly interested in the theoretical perspective even if practically not required ever) 回答1: Well, it

问题 How to test if an object is a vector, i.e. mode logical , numeric , complex or character ? The problem with is.vector is that it also returns TRUE for lists and perhaps other types: > is.vector(list()) [1] TRUE I want to know if it is a vector of primitive types. Is there a native method for this, or do I have to go by storage mode? 回答1: There are only primitive functions, so I assume you want to know if the vector is one of the atomic types. If you want to know if an object is atomic, use is

问题 How to test if an object is a vector, i.e. mode logical , numeric , complex or character ? The problem with is.vector is that it also returns TRUE for lists and perhaps other types: > is.vector(list()) [1] TRUE I want to know if it is a vector of primitive types. Is there a native method for this, or do I have to go by storage mode? 回答1: There are only primitive functions, so I assume you want to know if the vector is one of the atomic types. If you want to know if an object is atomic, use is

问题 I need to deploy a list of GCP compute instances. How do I loop for_each through the "vms" in a list of objects like this: "gcp_zone": "us-central1-a", "image_name": "centos-cloud/centos-7", "vms": [ { "hostname": "test1-srfe", "cpu": 1, "ram": 4, "hdd": 15, "log_drive": 300, "template": "Template-New", "service_types": [ "sql", "db01", "db02" ] }, { "hostname": "test1-second", "cpu": 1, "ram": 4, "hdd": 15, "template": "APPs-Template", "service_types": [ "configs" ] } ] } 回答1: Seem's like I

问题 Does anybody know how can I filter data even the passing value is False, it so hassle to make lot of conditions I think there is a way to filter data even the value is false or empty. views.py def sample(request): if request.method=='POST': province = request.POST.get('province', False) municipality = request.POST.get('municipality', False) barangay = request.POST.get('barangay', False) status = request.POST.get('stats', False) batch= request.POST.get('Pbatch', False) it_batch= request.POST

问题 I have an array of objects that looks like this: "data": [ { "workout_id": 1, "user_id": 1, "shotLocation": 27, "shotAttempts": 20,"shotsMade": 19, "id": 1 }, { "workout_id": 2, "user_id": 1, "shotLocation": 1, "shotAttempts": 10, "shotsMade": 9, "id": 2 }, { "workout_id": 2, "user_id": 1, "shotLocation": 10, "shotAttempts": 10, "shotsMade": 7, "id": 3 }, { "workout_id": 2, "user_id": 1, "shotLocation": 1, "shotAttempts": 30, "shotsMade": 29, "id": 4 }, { "workout_id": 3, "user_id": 5,

问题 I have an array of objects that looks like this: "data": [ { "workout_id": 1, "user_id": 1, "shotLocation": 27, "shotAttempts": 20,"shotsMade": 19, "id": 1 }, { "workout_id": 2, "user_id": 1, "shotLocation": 1, "shotAttempts": 10, "shotsMade": 9, "id": 2 }, { "workout_id": 2, "user_id": 1, "shotLocation": 10, "shotAttempts": 10, "shotsMade": 7, "id": 3 }, { "workout_id": 2, "user_id": 1, "shotLocation": 1, "shotAttempts": 30, "shotsMade": 29, "id": 4 }, { "workout_id": 3, "user_id": 5,