题解 | #实现抽象方法#

public class Main {

    public static void main(String[] args) {
        // Sub是需要你定义的子类
        Base base = new Sub();

        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNextInt()) {
            int x = scanner.nextInt();
            int y = scanner.nextInt();
            base.setX(x);
            base.setY(y);
            System.out.println(base.calculate());
        }
    }

}

 abstract class Base {

    private int x;
    private int y;
   
   public Base(){
        
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public int calculate() {
        if (avg() == 0) {
            return 0;
        } else {
            return sum() / avg();
        }
    }

    /**
     * 返回x和y的和
     */
    public abstract int sum();

    /**
     * 返回x和y的平均值
     */
    public abstract int avg();

}

class Sub extends Base {
     public Sub(){
        super();
    }
    
    //调用父类方法super.getX()+super.getY(),并删除abstract方法的关键字
    public   int sum(){
        return super.getX()+super.getY();
        
    }
    
    public  int avg(){
        return (super.getX()+super.getY())/2;
    }
    //write your code here......
}