[Interview Question] Comparison of interface and abstract class after Java 8

Comparison of interfaces and abstract classes after Java 8

声明：此博文是因为我在百度上找了很多抽象类与接口的区别，发现都没有把Java 8的新特性描述好，所以自己百度总结了一下，如有遗漏，请私信！

Same point

• Can not be instantiated
• Are included as implementation methods
• All subclasses must be implemented as implementation methods

the difference

• The abstract class is defined by abstract, and the interface is defined by interface
• Abstract classes can only be inherited by single, but can be inherited multiple times, interfaces can not only inherit multiple interfaces, but also be implemented multiple times
• Abstract classes can contain any number of methods with method bodies, but interfaces are not allowed before Java 7, and Java 8 allows multiple default methods
• Abstract classes can have constructors, mainly for initialization, but they cannot be adjusted by themselves. They can only be adjusted by subclasses. There is no constructor for interfaces.
• The access modifier for abstract class access can be arbitrary, but the interface is public by default, and the variables in the interface are public static final modification by default
• An abstract class can have a main method, and we can run it; an interface cannot have a main method.

Attached

Abstract class:

public abstract class Employee
{
    
    
   private String name;
   private String address;
   private int number;
   // 构造器
   public Employee(String name,String address,int number){
    
    
		this.name = name;
		this.address= address;
		this.number= number;
	}
   
   public abstract double computePay();
   
   //其余代码
}

interface:

public interface IDemo {
    
    

    // 默认方法，可以有多个
    default void fun() {
    
    
        System.out.println("Default method");
    }

    public static final Integer DEFAULT_VAR = 1;

    // 抽象方法
    public abstract void doGet();
}