java - Java中的"new way for loop"，不起作用，建议吗？

Question

这是我的问题:我试图使用java中新的for循环来打印一些带有 double 的字符串。当我编译代码时，没有错误，但没有输出，就像 for 循环不起作用一样，有什么帮助吗？

循环就在最后，为了确定起见，我打印了所有代码。

abstract class Figure3D {

private float[] center;

protected void setCenter(float[] center){this.center = center;}

public abstract double calcolateVolumn();

protected abstract String figureType();

public void printVolumn(){
  System.out.println("Volumn "+ figureType() + calcolateVolumn());
}

}


class Cube extends Figure3D{

private float side;

public Cube(float side, float[] center){
  this.side = side;
  setCenter(center);
}

@Override
protected String figureType(){
    return "Cube ";
}

@Override
public double calcolateVolumn(){
    return side*side*side;
}

}

class Sphere extends Figure3D {

private float radius;

public Sphere(float radius, float[] center){
  this.radius = radius;
  setCenter(center);
}

protected String figureType(){return "Sphere ";}

public double calcolateVolumn(){return ((4f/3f)*radius*radius*radius*3.14f);}

}

import java.util.ArrayList;
import java.util.List;

class TridimensionalFigures {
public static void main(String[] args) {
    List<Figure3D> figures3d = new ArrayList<>(10);
    Sphere sphere;
    Cube cube;

    for (int i = 0; i < figures3d.size(); i++) {
        sphere = new Sphere(i, new float[] {i, i, i});
        figures3d.add(i, sphere);
        i++;
        cube = new Cube(i, new float[] {i, i, i});
    }

    //TOFIX: it needs to print out the volums of all the objects in the arraylist
    for (Figure3D figures : figures3d) {
        System.out.printf("The volumns is: %s %n", figures.calcolateVolumn());
    }
}
}

Answer 1

figures3d.size() 为 0，因此您没有向列表中添加任何内容。

尝试改变

for (int i = 0; i < figures3d.size(); i++) {

到

for (int i = 0; i < 10; i++) {