implements

What's the difference between 'extends' and 'implements' in TypeScript

由 假装没事ソ 提交于 2019-11-28 15:27:31
I would like to know what man and child have in common and how they differ. class Person { name: string; age: number; } class child extends Person {} class man implements Person {} Radim Köhler Short version extends means: The new class is a child . It gets benefits coming with inheritance. It has all properties, methods as its parent. It can override some of these and implement new, but the parent stuff is already included. implements means: The new class can be treated as the same "shape" , while it is not a child . It could be passed to any method where the Person is required, regardless of

What's the difference between the implements & extends keywords in Java [duplicate]

由 隐身守侯 提交于 2019-11-28 05:53:16
This question already has an answer here: Implements vs extends: When to use? What's the difference? 17 answers What's the difference between the following keywords in Java: implements , extends ? blahman An interface is an abstract specification of how a class should behave whilst a class is a concrete implementation of such a specification. Therefore, when you write implements you're saying that you are fulfilling some abstract specification in the implementation you've written. extends means that you take either an implementation ( class ) or specification ( interface ) and add to it with

Extending vs. implementing a pure abstract class in TypeScript

由 旧巷老猫 提交于 2019-11-28 04:28:17
Suppose I have a pure abstract class (that is, an abstract class without any implementation): abstract class A { abstract m(): void; } Like in C# and Java, I can extend the abstract class: class B extends A { m(): void { } } But unlike in C# and Java, I can also implement the abstract class: class C implements A { m(): void { } } How do classes B and C behave differently? Why would I choose one versus the other? (Currently, the TypeScript handbook and language specification don't cover abstract classes.) The implements keyword treats the A class as an interface, that means C has to implement

java.lang.Number doesn't implement “+” or any other operators?

由 99封情书 提交于 2019-11-28 00:12:33
问题 I'm creating a class which is supposed to be able to be used with an array of any type of number (float, int, etc), so here is one method I have: // T extends Number public synchronized T[] average() { Number[] ret = new Number[queue[0].length]; for (int i = 0; i < ret.length; ++i) { for (int j = 0; j < size; ++j) { ret[i] += queue[j][i]; // WTF ERROR?! } ret[i] /= size; // WTF ERROR?! } return (T[])ret; } Except this won't compile because "Number" doesn't implement the "+=" or "/=" operators

Why “extends” precedes “implements” in class declaration [closed]

由 半城伤御伤魂 提交于 2019-11-27 09:37:13
问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . Why must implement always be written after extend in a class declaration? For example: public class Register extends ActionSupport implements ModelDriven Why can it not be: public class Register implements

Extending vs. implementing a pure abstract class in TypeScript

由 老子叫甜甜 提交于 2019-11-27 05:16:15
问题 Suppose I have a pure abstract class (that is, an abstract class without any implementation): abstract class A { abstract m(): void; } Like in C# and Java, I can extend the abstract class: class B extends A { m(): void { } } But unlike in C# and Java, I can also implement the abstract class: class C implements A { m(): void { } } How do classes B and C behave differently? Why would I choose one versus the other? (Currently, the TypeScript handbook and language specification don't cover

What's the difference between the implements & extends keywords in Java [duplicate]

由 旧街凉风 提交于 2019-11-27 01:07:18
问题 This question already has an answer here: Implements vs extends: When to use? What's the difference? 18 answers What's the difference between the following keywords in Java: implements , extends ? 回答1: An interface is an abstract specification of how a class should behave whilst a class is a concrete implementation of such a specification. Therefore, when you write implements you're saying that you are fulfilling some abstract specification in the implementation you've written. extends means

What's the difference between 'extends' and 'implements' in TypeScript

由 醉酒当歌 提交于 2019-11-26 23:51:36
问题 I would like to know what man and child have in common and how they differ. class Person { name: string; age: number; } class child extends Person {} class man implements Person {} 回答1: Short version extends means: The new class is a child . It gets benefits coming with inheritance. It has all properties, methods as its parent. It can override some of these and implement new, but the parent stuff is already included. implements means: The new class can be treated as the same "shape" , while

Implements vs extends: When to use? What&#39;s the difference?

由 扶醉桌前 提交于 2019-11-26 01:29:13
问题 Please explain in an easy to understand language or a link to some article. 回答1: extends is for extending a class. implements is for implementing an interface The difference between an interface and a regular class is that in an interface you can not implement any of the declared methods. Only the class that "implements" the interface can implement the methods. The C++ equivalent of an interface would be an abstract class (not EXACTLY the same but pretty much). Also java doesn't support

“implements Runnable” vs “extends Thread” in Java

由 你说的曾经没有我的故事 提交于 2019-11-25 21:36:35
问题 From what time I\'ve spent with threads in Java, I\'ve found these two ways to write threads: With implements Runnable : public class MyRunnable implements Runnable { public void run() { //Code } } //Started with a \"new Thread(new MyRunnable()).start()\" call Or, with extends Thread : public class MyThread extends Thread { public MyThread() { super(\"MyThread\"); } public void run() { //Code } } //Started with a \"new MyThread().start()\" call Is there any significant difference in these two
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