Java 14.接口

public interface Complexity
        {
         public viod setComplexity(int complexity);
         public int getComplexity();
       }
        

public interface Complexity {

    public static void main(String[] args)
       {
        final float PI=3.14159f;//定义用于表示圆周率的常量PI  
            float getArea(float r);//定义一个用于计算面积的方法getArea()  
         float getCircumference(float r);//定义一个用于计算周长的方法getCircumference()  
     
    }
}



public class  Question implements Complexity   {

    private String question, answer;
    public float getArea(float r)   
          {  
              float area=PI*r*r;//计算圆面积并赋值给变量area  
              return area;//返回计算后的圆面积  
          }  
          public float getCircumference(float r)   
          {  
             float circumference=2*PI*r;      //计算圆周长并赋值给变量circumference  
             return circumference;           //返回计算后的圆周长  
         }  
         public static void main(String[] args)   
         {  
             Question c = new Question();  
            float f = c.getArea(2.0f);  
             System.out.println(Float.toString(f));  
         }  
     }