JDK8接口中默认方法

package com.cathy;

public interface Formula {

    double calculate(int a);
    
    default double sqrt(double b){  //定义默认方法，加default关键字
        return Math.sqrt(b);
    }
}

class ImplFormula{
    
    static Formula formula = new Formula() {
        @Override
        public double calculate(int a) {
            return Math.sqrt(a*100);
        }
    };

    public static void main(String[] args) {
        System.out.println( formula.calculate(1));
        System.out.println(formula.sqrt(16));
    }
}

结果：

10.0
4.0