public class Circle extends shape { final double p=3.14; double r=2.1; double c=2*p*r; double s=p*r*r; public double C(){ return c; System.out.println("圆形周长为"+c);}在这段代码中 return c 应放在System.out.println("圆形周长为"+c);后面。这是我运行的结果：矩形周长为13.2 ...
public class American extends People {
public void speak(){
System.out.println("美国人会说英语");
}
}
public class Initail {
public static void main(String[] args) {
People p1=new Chinese();
p1.speak();
People p2=new American();
p2.speak();
}
}
public abstract class People {
public abstract void speak();
}
public class Chinese extends People {
public void speak(){
System.out.println("中国人会说汉语");
}
}
