//期中考第三題 執行子類別或父類別建構元
//(3-1) 1.建立有1個字串的子類別建構元物件 2.接著執行同類別無參數建構元
//(3-2) 1.建立無參數的子類別建構元物件 2.接著執行父類別1字串1小數建構元
public class appsub extends app {
String color="WHITE";
public appsub() { super("正方體",2.0);//執行父類別1字串1小數建構元
System.out.println(color);
}
public appsub(String ss) {
this();//執行第4行同類別無參數建構元
color=ss;
System.out.println(color);
}
public static void main(String[] args) {
//appsub oapp=new appsub("BLUE");//執行有1個字串的建構元(第6行)
appsub oapp2=new appsub();//執行無參數的建構元(第4行)
}
}
---
public class app {
String shape="圓形";
double side = 1.0;
public app(){ System.out.println(shape + "A:" + side*3.1416); }
public app(String ss, Double dd)
{ shape=ss;
side=dd;
System.out.println(shape + "A:" + side*side);
}
}
----------------------
import java.util.*;
import java.math.*;
public class shape {
//印出圓面積
public shape(double dd) {System.out.println("圓形面積:"+ dd*dd* 3.1416);}
public shape(double dd,double ww) {System.out.println("矩形面積:"+ dd*ww);}
public shape(double a,double b,double c)
{
double s=(a+b+c)/2;
double area=Math.sqrt(s*(s-a)*(s-b)*(s-c));
System.out.println("三角形面積:"+ area);}
public static void main(String[] args) {
shape oo1 = new shape(3.0);
shape oo2 = new shape(3.0,4.0);
shape oo3 = new shape(3.0,4.0,5.0);
}
}
-------------test 1. 執行同類別無參數建構元 2.兩個字串的子類別建構元物件
//期中考第三題:執行子類別或父類別建構元
//(3-1) 1.建立有一個字串的子類別建構元物件 2.接著執行同類別無參數建構元
//(3-2) 1.建立無參數的子類別建構元物件 2.接著執行同類別無參數建構元
public class appsub extends app {
static String color="WHITE", color2="GREEN";
public appsub() { super("正方體","矩形"); //執行父類1字串1小數建構元
System.out.println(color);
}
public appsub(String ss){
this();//執行第四行同類別無參數建構元
color = ss;
System.out.println(color);
}
public static void main(String[] args) {
//appsub oapp = new appsub ("BLUE");//執行有一個字串的建構元 (第六行)
appsub oapp2 = new appsub (); //執行無參數的建構元(第四行)
}
}
---test
public class app {
String shape = "圓形";
double side = 1.0;
public app(){System.out.println(shape + "A: "+ side*3.1416);}
public app(String ss,String dd)
{ shape = ss;
//side = dd;
System.out.println(shape + "A: "+ side*side);
}
}
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