class

问题 What I mean by this, is opening a file with a Java code in it as a class, not as a file. So basically I want to: -> Open a pure text file in a self written Java application (.txt/.log/.java) -> Recognize class(es) in the file, for example: public class TestExample { private String example; public String getExample() { return example; } } I will open this in a hand-written program. Instead of recognizing the text in the file as a String or as pure text, it will find the class TestExample in it

问题 Is it mandatory to call the parent's constructor from the constructor in the child class constructor? To explain consider the following example: class Parent{ function __construct(){ //something is done here. } } class Child extends Parent{ function __construct(){ parent::__construct(); //do something here. } } This is quite normal to do it as above. But consider the following constructors of the class Child : function __construct(){ //Do something here parent::__construct(); } Is the above

问题 All I'm looking for is a list of possible values of classinfo since the documentation doesn't provide one and I can't seem to find one anywhere else online, let alone SO. 回答1: print([t for t in __builtins__.__dict__.values() if isinstance(t, type)]) Output (line-breaks inserted for readability): [ <class '_frozen_importlib.BuiltinImporter'>, <class 'bool'>, <class 'memoryview'>, <class 'bytearray'>, <class 'bytes'>, <class 'classmethod'>, <class 'complex'>, <class 'dict'>, <class 'enumerate'>

问题 Well, I've got such a code: public class Main { public static void main(String[] args) { Test t; //1 Integer i = new Integer(1); //2 t = new Test(); //3 System.out.println(Test4.a); //4 } } class Test { private int a = 10; private Test2 t2; //5 List<Test2> list = new ArrayList<Test2>() { { for (int i = 0; i < a; i++) { add(new Test2()); //6 } } }; } class Test2 extends Test3{ } class Test3 { } class Test4 { public static final int a = 4; } I don't know how (fully or partially) and when

问题 I was just reading the Python documentation about classes; it says, in Python "classes themselves are objects". How is that different from classes in C#, Java, Ruby, or Smalltalk? What advantages and disadvantages does this type of classes have compared with those other languages? 回答1: In Python, classes are objects in the sense that you can assign them to variables, pass them to functions, etc. just like any other objects. For example >>> t = type(10) >>> t <type 'int'> >>> len(t.__dict__)

问题 I can't find how copy is implemented for case class in scala. Can I check it somehow? I though Intellij could point me to implementation, but it doesn't want to jump and I have no idea why :/ 回答1: You can inspect the scala case class output using scalac -print ClassName.scala , as the copy is actually a compiler generated method. Here's a given example: case class Test(s: String, i: Int) This is the output after filtering out noise for copy : case class Test extends Object with Product with

问题 I can't find how copy is implemented for case class in scala. Can I check it somehow? I though Intellij could point me to implementation, but it doesn't want to jump and I have no idea why :/ 回答1: You can inspect the scala case class output using scalac -print ClassName.scala , as the copy is actually a compiler generated method. Here's a given example: case class Test(s: String, i: Int) This is the output after filtering out noise for copy : case class Test extends Object with Product with

问题 In python, is there a way I can use instance variables as optional arguments in a class method? ie: def function(self, arg1=val1, arg2=val2, arg3=self.instance_var): # do stuff.... Any help would be appreciated. 回答1: Try this: def foo(self, blah=None): if blah is None: # faster than blah == None - thanks to kcwu blah = self.instance_var 回答2: All the responses suggesting None are correct; if you want to make sure a caller can pass None as a regular argument, use a special sentinel and test

问题 my first question on StackOverflow. I'd like to be able to do something like: SomeClass mock = mock(SomeClass.class); String methodName = "someMethod"; OR Method method = ...someMethod... Both of these things (the mock and the method) would combine to do the following: when(mock.someMethod()).thenReturn(null); Of course, the 'null' value will be changed accordingly for my needs, but I am trying to determine two things: 1) Is it even possible to do something like this in Java? This = combining

问题 I had an error in a Typescript class method declaration, but I don't understand how the error message relates back to the bug. The message seems to be saying that 'this' is of type any , but we are in a class definition, and so I thought 'this' was really clear. Can someone please explain how the error message relates back to the bug? Original method: calcSize = function() { return this.width * this.length; // Error on this line }; // Error text: 'this' implicitly has type 'any' because it