父類Shape
package?com.imooc;

public?abstract?class?Shape?{
????public?abstract?void?perimeter(int?length);
????public?abstract?void?area(int?length);
}

子類
package?com.imooc;
public?class?Rectangle?extends?Shape?{
????
????@Override
????public?void?perimeter(int?length)?{
????????//?TODO?Auto-generated?method?stub
????????System.out.println("矩形周長為"+length*4);
????}
????@Override
????public?void?area(int?length)?{
????????//?TODO?Auto-generated?method?stub
????????System.out.println("矩形面積為"+length*length);
????}
}

子類
package?com.imooc;
public?class?Circle?extends?Shape?{
????
????@Override
????public?void?perimeter(int?length)?{
????????//?TODO?Auto-generated?method?stub
????????System.out.println("圓形周長為"+2*3.14*length);
????}
????@Override
????public?void?area(int?length)?{
????????//?TODO?Auto-generated?method?stub
????????System.out.println("圓形面積為"+3.14*length*length);
????}
}

package?com.imooc;
public?class?Initial?{
????public?static?void?main(String[]?args)?{
????????Shape?s1?=?new?Rectangle();
????????Shape?s2?=?new?Circle();
????????int?length?=?10;
????????s1.perimeter(length);
????????s1.area(length);
????????s2.perimeter(length);
????????s2.area(length);
????}
}

執行結果：
矩形周長為40
矩形面積為100
圓形周長為62.800000000000004
圓形面積為314.0