package?xxx;
public?abstract?class?Shape?{
????public?abstract?void?square();
?????public?abstract?void?zhouchang();?
?
}
package?xxx;
public??class?Rectangle?extends?Shape?{
?int?chang=8;
?int?kuan=6;
?int?square=chang*kuan;
??int?zhouchang=(chang+kuan)*2;
?
?
?@Override
?public?void?square()?{
??//?TODO?Auto-generated?method?stub
??
?}
?@Override
?public?void?zhouchang()?{
??//?TODO?Auto-generated?method?stub
??
?}?
?public?void?cal(){
?????System.out.println("矩形的面積為："+square+"?"+"周長為"+zhouchang);
?????
}
}
package?xxx;
public?class?Circle?extends?Shape?{
????double?r=6.00;
?double?square=3.14*r*r;
????double?zhouchang=0.50*3.14*r;
?
?@Override
?public?void?square()?{
??//?TODO?Auto-generated?method?stub
??
?}
?@Override
?public?void?zhouchang()?{
??//?TODO?Auto-generated?method?stub
??
?}?
?public?void?cal(){
????System.out.println("圓形的面積為："+square+"?"+"周長為"+zhouchang);
????}?
?}
package?xxx;
public?class?initail?{
?public?static?void?main(String[]?args)?{
???Shape?obj1=new?Circle();
??????Shape?obj2=new?Rectangle();
??????obj1.square();
??????obj1.zhouchang();
??????obj2.square();
??????obj2.zhouchang();
?}
}
2019-02-24
代碼里面沒用帶繼承的知識啊，在自動生成的方法里面沒有方法體。
沒有結果的原因是因為，你在子類中重新定義的新方法cal，而你創建的對象是由父類指向子類的，根本不能調用子類中的方法。
對于你的代碼，你可以試試看創建子類對象，直接用子類對象調用方法
Circle circle=new Circle();
circle.cal();
Rectangle rectangle=new Rectangle();
rectangle.cal();
2017-11-28
輸出結果的方法是
public?void?cal(){
????System.out.println("圓形的面積為："+square+"?"+"周長為"+zhouchang);
????}?
?}
所以測試類中應該添加?obj1.cal();?obj2.cal();