methods

问题 This question already has answers here : Determine if android app is the first time used (15 answers) Closed 3 years ago . How can I know if it is the first time the application launched? If you are answering please add a full code because I have read some answers and I didn't understand them. Thanks. 回答1: Use sharedPreferences for the persistent data storage.when the application first launched just save a boolean value in the shared Preferences.Then check each time. SharedPreferences

问题 I've finally decided to put the sort.data.frame method that's floating around the internet into an R package. It just gets requested too much to be left to an ad hoc method of distribution. However, it's written with arguments that make it incompatible with the generic sort function: sort(x,decreasing,...) sort.data.frame(form,dat) If I change sort.data.frame to take decreasing as an argument as in sort.data.frame(form,decreasing,dat) and discard decreasing, then it loses its simplicity

问题 Bellow is an example I found on Tutorials Points, an example of a constructor. I got most of them, but I just don't get why you need a constructor and a method. public Puppy(String name){ System.out.println("Passed Name is :" + name ); } My question is, what stops you from doing this instead? public static void Puppy(String name){ System.out.println("Passed Name is: "+name); } Doesn't these two do the same thing once called? Here is the full program for reference: public class Puppy { int

问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 3 years ago . I wonder if can I say that a constructor is a special case of a method ? 回答1: You can say anything. Whether anyone will disagree with you depends on the context. Some language communities and standards define things that way. More elaborately, it depends on what you mean by a

问题 I'm trying to check if a circle is contained within another circle. I'm not sure if the math behind it is the problem or if its my if statement because I keep getting True for anything I pass. #Get_center returns (x,y) #Get_radius returns radius length def contains(self,circle): distance = round(math.sqrt((circle.get_center()[0]-self.get_center()[0])**2 + (circle.get_center()[1] - self.get_center()[1])**2)) distance_2 = distance + circle.get_radius() if distance_2 > distance: return True

问题 I just found out about a very interesting Java trick: void method1(Integer... a){ } So you can give this method as many integers as you want. Now if I have a similar (overloaded) method like this: void method1(int a, int b){ } Which method runs when I execute the following line: method1(1, 2); Well, I could find that out very easily by just testing it out with different method instructions but when I think about the "rules" in "overloading" methods then I have to make sure that every

问题 For one Model called Email.rb, I have a method shown below called new_todos. This same method needs to be made available for Call.rb, Postalcard.rb, etcetera. Rather than cutting and pasting this exact snippet across multiple Models of Active Records, how can I have it written just once and make it available to the appropriate Models? I suspect it could work by putting a module in the /lib folder, but I'm not exactly sure....thanks! def new_todos Contact.campaign_id_is(self.campaign_id).each

问题 I am trying to make a method that will calculate the age of a person. I want the calculation to be done under the second public static int getAge . If the person is born after the current date i want it to print out error -1. How do I compare the two SimpleDate values dateBd and dateRef in order to get an int value for age? public static SimpleDate today() { Calendar todayCal = Calendar.getInstance(); SimpleDate todayDate = new SimpleDate(); todayDate.setDate(todayCal.get(Calendar.MONTH) + 1,

问题 we'd defend against the code crackers who can operate on the whole operation system who may read the encoded class-file via "java.io" and save the copy we'd protect java-based application's intellectual property this requirement was raised by several customers, so it has realistic value. Simplex Java-JDK-JVM solution like securityManager without native code/tool can NOT be accepted because it's easy to be bypassed, since cracker have the admin privilege on the OS in this scenario. 回答1: You

问题 I know there are a lot of threads talking about this and believe me I've seen all of them, but I think I'm a little slow and cant figure out how to do this so here is the thing! I have one form public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button4_Click(object sender, EventArgs e) { adi mYadi= new adi(); adi.paso(); } private void Form1_Load(object sender, EventArgs e) { } public void l8u(string l ) { label8.Text = l; } } The l8u method is supposed