📌  相关文章
📜  抽象类和接口之间的差异

📅  最后修改于: 2020-09-24 03:16:35             🧑  作者: Mango

抽象类和接口之间的区别

抽象类和接口都用于实现抽象，我们可以在其中声明抽象方法。抽象类和接口都无法实例化。

但是，下面给出的抽象类和接口之间有许多区别。

Abstract class Interface
1) Abstract class can have abstract and non-abstract methods. Interface can have only abstract methods. Since Java 8, it can have default and static methods also.
2) Abstract class doesn’t support multiple inheritance. Interface supports multiple inheritance.
3) Abstract class can have final, non-final, static and non-static variables. Interface has only static and final variables.
4) Abstract class can provide the implementation of interface. Interface can’t provide the implementation of abstract class.
5) The abstract keyword is used to declare abstract class. The interface keyword is used to declare interface.
6) An abstract class can extend another Java class and implement multiple Java interfaces. An interface can extend another Java interface only.
7) An abstract class can be extended using keyword “extends”. An interface can be implemented using keyword “implements”.
8) A Java abstract class can have class members like private, protected, etc. Members of a Java interface are public by default.
9)Example:
public abstract class Shape{
public abstract void draw();
}		 Example:
public interface Drawable{
void draw();
}

简单来说，抽象类实现部分抽象(0到100％)，而接口实现完全抽象(100％)。

Java抽象类和接口的示例

让我们看一个简单的示例，其中我们同时使用接口和抽象类。

"//Creating interface that has 4 methods  
interface A{  
void a();//bydefault, public and abstract  
void b();  
void c();  
void d();  
}  
  //Creating abstract class that provides the implementation of one method of A interface  
abstract class B implements A{  
public void c(){System.out.println("I am C");}  
}  
  //Creating subclass of abstract class, now we need to provide the implementation of rest of the methods  
class M extends B{  
public void a(){System.out.println("I am a");}  
public void b(){System.out.println("I am b");}  
public void d(){System.out.println("I am d");}  
}  
  //Creating a test class that calls the methods of A interface  
class Test5{  
public static void main(String args[]){  
A a=new M();  
a.a();  
a.b();  
a.c();  
a.d();  
}}

输出：

I am a
I am b
I am c
I am d