super

问题 I'm creating a game. When I'm extending my Block class it shows an error. Error: Implicit super constructor Block() is undefined. Must explicitly invoke another constructor Code: Game.java: package lt.projecturanium; import java.awt.BorderLayout; import java.awt.Canvas; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferStrategy; import java.util.HashMap; import javax.swing.JFrame; import lt.projecturanium.blocks

问题 I encountered a problem that confused me, it is the keyword 'super', my test code is like this: package test; public class Parent { private String name; public Parent(){ this.name = "parent"; } public String getName() { return name; } public void setName(String name) { this.name = name; } public void showName(){ System.out.println(this.name); } } public class Child extends Parent{ public Child(){ this.setName("Child"); } public void showName(){ System.out.println(super.getClass().toString());

问题 I want to use the superclass to call the parent method of a class while using a different class. Class AI(): ... for i in self.initial_computer_group: if i.rect.x == current_coords[0] and i.rect. y== current_coords[1]: i.move(coords_to_move[0], coords_to_move[1]) i.move() calls a method from an inherited class , when I want the original method from the parent class. self.initial_computer_group contains a list of objects which are completely unrelated to the AI class. I know I need to somehow

问题 I saw getView implementations that used convertView parameter directly: if(convertView!=null) ... return convertView Another implementations call super.getView: View view = super.getView( position, convertView, parent ); if(view!=null) ... return view My question is, What is the right method? 回答1: I guess you are talking about Adapter.getView(). Which adapter are you extending? Most adapters have no implementation of getView() themselves and expect that you check if convertView is null before

问题 I've been doing research on Python 3 (my code sample uses 3.7.2) and how to properly use super() when a class inherits more than one class. I've read this page, and this page and this article. I think the problem is that the SO links are for an older version of Python, while the article is for Python 3, but it's still confusing. Suppose I had the following code (don't worry if you think that the relationship can be modeled better, this is just an example to illustrate my problem): class

问题 I wanted to ask a clever question about using Canvas as a container, but writing my example code I stumbled over something weird. Here is the code so far: import Tkinter as tk class CCanvas(tk.Canvas): def __init__(self,master,*args,**kwargs): super(CCanvas,self).__init__(master=master,*args,**kwargs) if __name__ == '__main__': root= tk.Tk() cc = CCanvas(root) cc.pack() root.mainloop() Now this code should not do much. The class CCanvas just inherits from Canvas, doesn't implement anything,

问题 I can't come up with a very good description of this in words, so, please take a look at this example: trait Base { def foo = "Base" } trait One extends Base { override def foo = "One <: " + super.foo } trait Two extends Base { override def foo = "Two <: " + super.foo } new Base with One with Two {} foo This prints: Two <: One <: Base , which is what I expect. Now, I am trying to add another level, so that overriding traits would not have to call super explicitly. Like this: trait Base { def

问题 I keep getting an error saying that "call to super must be the first statement in the constructor". The problem is that it is the first statement in my constructor. public void CheckingAccountCustomer(int a){ super(n, p, b); accountNo = a; } And here is my superclass for this as well. public void customer(String n, int p, double b){ name = n; pin = p; balance = b; } What am I doing wrong here? 回答1: This code public void customer(String n, int p, double b){ is not a constructor. Constructors

问题 the idea is to to have multiple widgets on a page and include all js and css files needed form this 'widgets' (it's easy to manage files this way). Duplicated files is not a problem. Every widget's template is included into a page by {%include%} From inside widget's template I'm trying to add content to parent's block: PARENT: {%block js%} {%endblock%} WIDGET {%block js%} {{block.super}} ///my widget spectyfic JS {%end block%} this is giving an error with {{block.super}}: Caught

问题 Hello and thanks for reading! I use a "for" to read every object in an arraylist, and want to check the string that returns the function getType() for each object, which exists in the extended class of the objects. for(int i=0; i<cat.items.size(); i++) { if ( cat.items.get(i).super.getType().equals(type) ); { However, I get the error MainApp.java:17: error: '(' expected if ( cat.items.get(i).super.getType().equals(type) ); ^ I think that I don't user "super" correctly. Can you offer an