casting

问题 I am using this code for getting contact number from contacts app but when I want to show the number in label I get this warning and doesn't work: Cast from 'CNPhoneNumber' to unrelated type 'String' always fails func contactPicker(_ picker: CNContactPickerViewController, didSelect contacts: [CNContact]) { contacts.forEach {(contact) in for number in contact.phoneNumbers{ let phone = number.value print(phone) numberLabel.text = phone as! String } } } 回答1: TRY : if let phone = number.value as?

问题 I was following a tutorial for NativeExpressAdView inside RecyclerView from this link which was provided by google. In this tutorial List was taken as Object Model Class. But my Recylerview has my own custom Model class name as: Artical. That's why I am doing some changes in my code. My code is below. ArticleAdapter.java package com.prof.rssparser.example; import android.content.Context; import android.content.DialogInterface; import android.support.v7.widget.RecyclerView; import android.text

问题 I have a question about asynchronous method calls in java, especially about the response value of the async method. The situation is the following: The async method I want to call is.. public void getSpeed(IResponseListener listener) { .... } The interface of the listener is... interface IResponseListener { public void response(ResponseEvent event); } This method is called when the async method has a response value My problem now is that the class ResponseEvent has an attribute response that

问题 Another way to ask the same question is, given 2 classes A and B, is it synonymous to say: "Object A can be cast into B" and "Object A is a descendant of B"? Thanks, JDelage Edit: Clarified the question to make it clearer that both A and B are classes. 回答1: " Java - Can you cast an object into a class it doesn't extend? " - No, you can't. " Basically, is it synonymous to say: "Object A can be cast into B" and "Object A is a direct descendant of B"? " - Yes. Plus in the case when A is of a

问题 Another way to ask the same question is, given 2 classes A and B, is it synonymous to say: "Object A can be cast into B" and "Object A is a descendant of B"? Thanks, JDelage Edit: Clarified the question to make it clearer that both A and B are classes. 回答1: " Java - Can you cast an object into a class it doesn't extend? " - No, you can't. " Basically, is it synonymous to say: "Object A can be cast into B" and "Object A is a direct descendant of B"? " - Yes. Plus in the case when A is of a

问题 I've got a vector of mutable references: type T = String; let mut mut_vec: Vec<&mut T> = vec![]; I want to pass (a copy of) it into a function that takes a vector of immutable references: fn cool_func(mut immut_vec: Vec<&T>) -> bool {false} How can I do this? 回答1: You can dereference and reborrow the mutable references, then add them to a new Vec : fn main() { let mut st = String::new(); let mut_vec = vec![&mut st]; let immut_vec = mut_vec.into_iter().map(|x| &*x).collect(); cool_func(immut

问题 I'm on Databricks and I'm working on a classification problem. I have a DataFrame with 2000+ columns. I want to cast all the columns that will become features to double. val array45 = data.columns drop(1) for (element <- array45) { data.withColumn(element, data(element).cast("double")) } data.printSchema() The cast to double is working but I'm not saving it in the DataFrame called Data. If I create a new DataFrame in the loop ; outside of the for loops my DataFrame won't exist. I do not want

问题 I'm on Databricks and I'm working on a classification problem. I have a DataFrame with 2000+ columns. I want to cast all the columns that will become features to double. val array45 = data.columns drop(1) for (element <- array45) { data.withColumn(element, data(element).cast("double")) } data.printSchema() The cast to double is working but I'm not saving it in the DataFrame called Data. If I create a new DataFrame in the loop ; outside of the for loops my DataFrame won't exist. I do not want

问题 This must be a really dumb question because I cant find an answer online.... I know that casting is changing one datatype to another. How is this button ever changing it's data dype? Button button = (Button)findViewById(R.Bla.Bla) Why cant we just write Button button = New Button() And then assign the xml to it another way? Please explain, I'm lost. 回答1: See In Android You can create the UI Elements in two ways: 1. create UI elements through layouts (.xml) files. And to use them in java class

问题 I have data that can be represented in two different forms (for historical reasons that I won't go into). The first is a tuple of tuple s: t = (('a', 'x', 3), ('a', 'f', 1), ('b', 'r', 23), ('b', 'e', 3)) And the second as a dict of dict s: d = {'a' : {'x': 45, 'f' : 4}, 'b' : {'r' : 34, 'e' : 45}} Same data, different representation. I now need to end up with a combination of the two (and must maintain the tuple-of-tuples form rather than the nested dict form), with the values summed . i.e.