Java 继承接口和多个接口示例
Java中的接口类似于类，但是它仅包含final和static的抽象方法和字段。
就像类一样，您可以使用extend关键字将一个接口从另一个接口继承，如下所示-
interface ArithmeticCalculations{
public abstract int addition(int a, int b);
public abstract int subtraction(int a, int b);
}
interface MathCalculations extends ArithmeticCalculations{
public abstract double squareRoot(int a);
public abstract double powerOf(int a, int b);
}但是，实现子类时，需要在两个接口中都为抽象方法提供主体。
示例
在以下示例中，我们创建了两个接口-具有两个抽象方法（加法和减法）的ArithmeticCalculations和MathCalculations，其中，
import java.util.Scanner;
interface ArithmeticCalculations{
public abstract int addition(int a, int b);
public abstract int subtraction(int a, int b);
}
interface MathCalculations extends ArithmeticCalculations{
public abstract double squareRoot(int a);
public abstract double powerOf(int a, int b);
}
public class ExtendingInterfaceExample implements MathCalculations{
public int addition(int a, int b) {
return a+b;
}
public int subtraction(int a, int b) {
return a-b;
}
public double squareRoot(int a) {
return Math.sqrt(a);
}
public double powerOf(int a, int b) {
return Math.pow(a, b);
}
public static void main(String args[]){
Scanner sc = new Scanner(System.in);
System.out.println("Enter the value of a: ");
int a = sc.nextInt();
System.out.println("Enter the value of b: ");
int b = sc.nextInt();
ExtendingInterfaceExample obj = new ExtendingInterfaceExample();
System.out.println("Result of addition: "+obj.addition(a, b));
System.out.println("Result of subtraction: "+obj.subtraction(a, b));
System.out.println("Square root of "+a+" is: "+obj.squareRoot(a));
System.out.println(a+"^"+b+" value is: "+obj.powerOf(a, b));
}
}输出结果
Enter the value of a: 4 Enter the value of b: 3 Result of addition: 7 Result of subtraction: 1 Square root of 4 is: 2.0 4^3 value is: 64.0
继承多个接口
以相同的方式，您可以使用extends关键字从一个接口扩展多个接口，方法是使用逗号(,)分隔接口，如下所示：
interface MyInterface extends ArithmeticCalculations, MathCalculations{示例
以下是Java程序演示如何从单个接口扩展多个接口。
interface ArithmeticCalculations{
public abstract int addition(int a, int b);
public abstract int subtraction(int a, int b);
}
interface MathCalculations {
public abstract double squareRoot(int a);
public abstract double powerOf(int a, int b);
}
interface MyInterface extends MathCalculations, ArithmeticCalculations {
public void displayResults();
}
public class ExtendingInterfaceExample implements MyInterface {
public int addition(int a, int b) {
return a+b;
}
public int subtraction(int a, int b) {
return a-b;
}
public double squareRoot(int a) {
return Math.sqrt(a);
}
public double powerOf(int a, int b) {
return Math.pow(a, b);
}
public void displayResults(){
Scanner sc = new Scanner(System.in);
System.out.println("Enter the value of a: ");
int a = sc.nextInt();
System.out.println("Enter the value of b: ");
int b = sc.nextInt();
ExtendingInterfaceExample obj = new ExtendingInterfaceExample();
System.out.println("Result of addition: "+obj.addition(a, b));
System.out.println("Result of subtraction: "+obj.subtraction(a, b));
System.out.println("Square root of "+a+" is: "+obj.squareRoot(a));
System.out.println(a+"^"+b+" value is: "+obj.powerOf(a, b));
}
public static void main(String args[]){
new ExtendingInterfaceExample().displayResults();
}
}输出结果
Enter the value of a: 4 Enter the value of b: 3 Result of addition: 7 Result of subtraction: 1 Square root of 4 is: 2.0 4^3 value is: 64.0