排序方法是正确的..但是没有排序成功...求指点~~~~
public class Testshape{
public static void main(String[] args){
Shape[] c = new Circle[5];
int i;
for( i=0; i<c.length; i++)
c[i] = new Circle(i);
for( i=0; i<c.length; i++)
System.out.println(c[i].toString());
Sort(c);//执行排序方法后...结果没变
for( i=0; i<c.length; i++)
System.out.println(c[i].toString());
}
public static void Sort(Shape[] list){
Shape currentMax;
int currentMaxIndex;
for(int i = list.length - 1;i >= 0;i--){
currentMax = list[i];
currentMaxIndex = i;
for(int j = i ;j >=0;j--){
if(list[i].getArea()<list[j].getArea()){
currentMax = list[j];
currentMaxIndex = j;
}
}//System.out.println(currentMax.toString());
if(currentMaxIndex != i){
list[currentMaxIndex] = list[i];
list[i] = currentMax;
}
}
}
}
class Shape{
protected double compareTo(Shape s){return 0;}
protected double getPerimeter(){return 0;}
protected double getArea(){return 0;}
public double getRadius(){return 0;}
public void setRadius(double r){}
}
class Circle extends Shape{
private double radius;
public Circle(){}
public Circle(double r){radius = r;}
public double getRadius(){return radius;}
public void setRadius(double r){radius = r;}
public String toString()
{
System.out.println( "[Circle]radius = "+radius);return "";
}
public double getPerimeter(){return 2*3.1415*radius;}
public double Area(){return 3.1415*radius*radius;}
}
/*class Rectangle extends Shape{
private double length;
private double width;
public Rectangle(double l,double w){length = l;width = w;}
public double getLength(){return length;}
public void setLength(double l){length = l;}
public double getWidth(){return width;}
public void setWidth(double w){width = w;}
public String toString()
{
System.out.println("[Rectangle]length = "+length+"and width = "+width);return "";
}
public double getPerimeter(){return 2*(length+width);}
public double getArea(){return length*width;}
}
*/
------解决方案--------------------
- Java code
//用数组没问题的，看了一下你的程序，发现很多问题//首先，Circle的toString有问题public String toString(){//System.out.println( "[Circle]radius = "+radius);return ""; //打印是打印了，但是正确的信息没返回 return String.format("[Circle]radius = %.2f", radius);}其次Circle的getArea方法没有重写public double Area(){return 3.1415*radius*radius;} //方法名和父类方法名不一样，而实际比较调用的时候是调用getArea，所以返回的是父类的getArea的返回值0，所以比较没有意义，导致没有发生排序//另，1L的排序方法有个地方失误了public static void Sort(Shape[] list){ for(int i=0; i<list.length; i++){ for(int j=1 ;j<list.length-i; j++){//之前这里笔误为j=i+1了 if(list[j].getArea()<list[j-1].getArea()){ Shape tmp = list[j]; list[j] = list[j-1]; list[j-1] = tmp; } } }}