Question

求Java大神帮我做下这几道题，急急急！！拜托了！

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Answer 1

三
1. A1.class
2. j<=9 j==9 ""
3. 90 7.5 42
四
public class Test{
public static void main(String[] args){
Circle c = new Circle();
c.r = 1.5f;
System.out.println("面积:"+c.area());
System.out.println("周长:"+c.len());
}
}

Answer 2

捧场

Answer 3

三 1）A1.class 2） j <= i i == j 3）90 7.5 42
四
package com.a;

public class Calculate extends Circle{
public static void main(String[] args) {
Calculate cal = new Calculate();
cal.r = 1.5f;
double a = cal.area();
double l = cal.len();
System.out.println("半径为"+cal.r+"的圆的面积为："+ a);
System.out.println("半径为"+cal.r+"的圆的周长为："+ l);
}
}