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                        /Java入門第二季 升級版

4-3抽象類課后疑問路過的大俠給看看哪里不對的謝謝

父類
package?imooc02;

public?abstract?class?Shape?{
????public?abstract?void?Perimeter();
????public?abstract?void?Area();

}
子類01
package?imooc02;

public?class?Rectangle?extends?Shape?{

????@Override
????public?void?Perimeter()?{
????????//?TODO?Auto-generated?method?stub
????????double?a;
????????double?b;
????????double?c;
????????double?c=?(a+b)*(a+b);
????????System.out.println("長方形的周長為"+c);
????????}
????

????@Override
????public?void?Area(){
????????//?TODO?Auto-generated?method?stub
????????????double?a?;
????????????double?b;
????????????double?s;
????????double?s=?a*b;
????????System.out.println("長方形的的面積為"+s);

????}

}
子類02
package?imooc02;

public?class?Circle?extends?Shape?{

????@Override
????public?void?Perimeter(){
????????//?TODO?Auto-generated?method?stub
????????double?π;
????????double?d;
????????private?double?c?;
????????private?double?c=?π*d;
????????System.out.println("圓的周長是："+c);
????????

????}

????@Override
????public?void?Area(){
????????//?TODO?Auto-generated?method?stub
????????double?π;
????????double??d;
????????double?s;
????????double?s=?π*((d/2)*(d/2));
????????System.out.println("圓的面積是:"+s);

????}

}?????

測試類
package?imooc02;

public?class?Test?{
????public?static?void?main(String[]?args)?{
????????Shape?a1=new?Rectangle();
????????a1.Perimeter();
????????a1.Area();
????????Shape?a2=new?Circle();
????????a2.Perimeter();
????????a2.Area();
????}

}

ART原藝美學

2017-03-08

源自：Java入門第二季升級版 10-3

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3 回答

藍_塵回答被采納 +3 積分
2017-03-08

將double?π 定義為常量 final PI=3.14;試試

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ART原藝美學提問者

這回對了嗎大圣

2017-03-08 回復有任何疑惑可以回復我~

ART原藝美學提問者

謝謝指導

2017-03-08 回復有任何疑惑可以回復我~

ART原藝美學提問者

非常感謝！

2017-03-09 回復有任何疑惑可以回復我~

kirito_yes
2017-03-18

既然一個類里面兩個方法的變量都一樣的話，可以直接拿出來啊，在類里定義寫一遍就好了。

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ART原藝美學提問者
2017-03-08

父類
package?imooc02;
?
public?abstract?class?Shape?{
????public?abstract?void?Perimeter();
????public?abstract?void?Area();
?
}
子類
package?imooc02;
?
public?class?Rectangle?extends?Shape?{
?
????@Override
????public?void?Perimeter()?{
????????//?TODO?Auto-generated?method?stub
????????double?a=10.0;
????????double?b=10.0;
????????double?c;
?????????c=?(a+b)*2;
????????System.out.println("長方形的周長為"+c);
????????}
?????
?
????@Override
????public?void?Area(){
????????//?TODO?Auto-generated?method?stub
????????????double?a=10.0?;
?????????????
????????????double?b=10.0;
?????????????
????????????double?s;
?????????s=?a*b;
????????System.out.println("長方形的的面積為"+s);
?
????}
?
}
子類02
?
package?imooc02;
?
public?class?Circle?extends?Shape?{
?
????@Override
????public?void?Perimeter(){
????????//?TODO?Auto-generated?method?stub
????????final?double?PI=3.14;
????????double?d=9.0;
?????????double?c?;
???????????c=?PI*d;
????????System.out.println("圓的周長是："+c);
?????????
?
????}
?
????@Override
????public?void?Area(){
????????//?TODO?Auto-generated?method?stub
????????final?double?PI=3.14;;
?????????double??d=9.0;
????????double?s;
?????????s=?PI*(d/2);
????????System.out.println("圓的面積是:"+s);
?
????}
?
}?????
測試類
package?imooc02;
?
public?class?Test?{
????public?static?void?main(String[]?args)?{
????????Shape?a1=new?Rectangle();
????????a1.Perimeter();
????????a1.Area();
????????Shape?a2=new?Circle();
????????a2.Perimeter();
????????a2.Area();
????}
?
}
?
長方形的周長為40.0
長方形的的面積為100.0
圓的周長是：28.26
圓的面積是:14.13

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