我一直在看我的源代碼,無法弄清楚它有什麼問題。 我認爲這個問題與Circle類有關。當我從 DriverCircle類中調用mutators和訪問器時,它會給我提供錯誤的輸出。對於getDiameter,它只是打印出0。爲什麼我的setter和getter方法不起作用?
public class Circle{
private double radius;
private double pi;
private double diameter;
private double circumference;
private double area;
public Circle(){
pi = Math.PI;
radius = 0;
}
public Circle(double radius){
this.radius = radius;
}
public void setDiameter(){
diameter = (2 * radius);
}
public double getDiameter(){
//diameter = 2 * radius;
return diameter;
}
public void setCircumference(){
circumference = (2 * pi * radius);
}
public double getCircumference(){
//circumference = 2 * pi * radius;
return circumference;
}
public double getArea(){
//area = pi * Math.pow(radius, 2);
return area;
}
public void setArea(){
area = (pi * Math.pow(radius, 2));
}
public void setRadius(double radius){
this.radius = radius;
}
public double getRadius(){
return radius;
}
public String toString(){
return "The radius is " + radius;
}
}
(該測試儀)...當你提供構造函數值
import java.util.Scanner;
public class CircleDriver {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("Please enter the radius: ");
Circle[] circles = new Circle[10];
Circle objectCircle = new Circle();
objectCircle.setRadius(input.nextDouble());
circles[1] = new Circle();
circles[2] = new Circle(2.0);
circles[3] = new Circle(3.5);
circles[4] = new Circle(5.0);
circles[5] = new Circle(0.0);
circles[6] = new Circle(15);
circles[7] = new Circle(25);
circles[8] = new Circle(-7);
circles[9] = new Circle(-10.0);
System.out.println("Initial call to toString():");
for (Circle c : circles)
{System.out.println("\t" + c);}
System.out.println("Call to getRadius (should be same as above):");
for (Circle r : circles)
{if (r != null)
{System.out.println("\t" + r.getRadius());}}
System.out.println("Call to getDiameter (should be twice the value shown above):");
for (Circle d : circles)
{if (d != null)
{System.out.println("\t" + d.getDiameter());}}
System.out.println("Calls to getCircumference:");
System.out.println("\tShould be 2 * PI: " + circles[1].getCircumference());
System.out.println("\tShould be 0.0: " + circles[5].getCircumference());
System.out.println("\nCall to getArea:");
System.out.println("\tShould be PI: " + circles[1].getArea());
System.out.println("\tShould be 0.0: " + circles[5].getArea());
System.out.println("Testing out the setRadius method:");
for (int i = 0; i < circles.length/2; i++)
{if (circles[i] != null)
{circles[i].setRadius(i);}}
System.out.println("Call to toString after setting the first half of the objects:");
for (Circle c : circles)
{System.out.println("\t" + c);}
}
}
您的setter方法應該有參數並使用參數來設置字段。否則它們實際上並不是setter方法。你當前的setter方法應該全部丟棄。 –
您不應該將直徑,圓周和麪積存儲爲變量。只需在使用半徑的getter方法中計算它們即可。 – Ignacio