object

问题 I have always this question burning in me. Why do people assign objects of subclass to a superclass reference as below: What exactly are the benefits and reasons that makes people do so? public static void main(String[] args) { A obj1 = new C(); //Why do this ? C obj2 = new C(); //When we can simply do this ??? } class A {} class B extends A {} class C extends B {} I understands all the logic where a Class Dog is an Animal but Animals are not essentially Dogs. I've also bumped into this link:

问题 Assume you define a class, which has a method which does some complicated processing: class A(object): def my_method(self): # Some complicated processing is done here return self And now you want to use that method on some object from another class entirely. Like, you want to do A.my_method(7) . This is what you'd get: TypeError: unbound method my_method() must be called with A instance as first argument (got int instance instead) . Now, is there any possibility to hack things so you could

问题 I have the following variable: _Data. The variable contains the following info: _Data Variable How can i access the message field? I tried _Data["messages"][0] - but it not wokring. I recieved the following error: Cannot apply indexing with [] to an expression of type 'object' What am i doing wrong? Thanks. 回答1: What am i doing wrong? _Data["messages"] is returning type object . You need to cast it to List<string> or IList<string> in order to use an indexer. var indexable = _Data["messages"]

问题 I used this "mobiledetect/mobiledetectlib": "^2.8" pkg of laravel for device detection and want to print the userAgent value.I call this method $this->device = new MobileDetect(); dd($this->device) After that i got this result: now i want to print userAgent value. I have tried these code but not working. dd($this->device->userAgent,$this->device["userAgent"]); 回答1: I was also facing this issue a few days ago. I have a solution for it you can try. $this->device->getUserAgent(); I was facing

问题 I have a typescript POJO as follows export interface Items { firstName?: String; lastname?: String; Address?: String; phoneNumber?: number; city?: String; state?: String; zipcode?: number; accountId?: number; status?: String; approvalStatus?: String; txId?: number; rxId?: number; txBankname?: String; rxBankName?: String; txCcy?: String; rxCcy?: String; txCcyAmt?:number; rxCcyAmt?:number; txDate?:date; rxDate?:date; } In my html file, I have a form with all the fields from above POJO. When a

问题 I have an array of objects like this input, and I want to nest some objects inside another objects (based if their parentId is the parents' forumId), I got the function working but up to 1 depth, how can I get it working for n depth? Any idea or optimizations are appreciated! EDIT: After pointing out, the input isn't necessarily ordered. const input = [ { forumId: 1, parentId: null, forumName: "Main", forumDescription: "", forumLocked: false, forumDisplay: true, }, { forumId: 2, parentId: 1,

问题 I have an array, that holds a large number of two-dimensional arrays: var myArray = [ [2260146,2334221,"copy"], [1226218,2334231,"copy"], [2230932,-1,"copy"], [2230933,-1,"copy"], [2230934,-1,"copy"] ] I need to convert this array into an object of the following form to send it as JSON: var json = [ { "s_id": 2260146, "t_id": 2334221, "type": "copy" }, { "s_id": 1226218, "t_id": 2334231, "type": "copy" }, { "s_id": 12, "t_id": -1, "type": "copy" } ] ("s_id" should be myArray[0][0] , "t_id

问题 I have an array, that holds a large number of two-dimensional arrays: var myArray = [ [2260146,2334221,"copy"], [1226218,2334231,"copy"], [2230932,-1,"copy"], [2230933,-1,"copy"], [2230934,-1,"copy"] ] I need to convert this array into an object of the following form to send it as JSON: var json = [ { "s_id": 2260146, "t_id": 2334221, "type": "copy" }, { "s_id": 1226218, "t_id": 2334231, "type": "copy" }, { "s_id": 12, "t_id": -1, "type": "copy" } ] ("s_id" should be myArray[0][0] , "t_id

问题 I'm trying to return the following in my reducer (react-redux) and it's giving me a syntax error: return { ...state, loginForm.email: action.payload.email } state = { loginForm: { email: '', password: '' } } so on I have babel preset stage 0 installed and es2015. This works fine: return { ..state, loginForm: action.payload } 回答1: Error you are getting because of the this key: loginForm.email It's not a valid object key. Write it like this: return { ...state, loginForm: { ...state.loginForm,

问题 I am surprised that my question was not asked (worded like the above) before. I am hoping that someone could break down this basic term "object" in the context of a OOP language like Python. Explained in a way in which a beginner like myself would be able to grasp. When I typed my question on Google, the first post that appears is found here. This is the definition: An object is created using the constructor of the class. This object will then be called the instance of the class. Wikipedia