Question

我编写以下程序来调用toString方法，但它无效。

import java.util.Scanner;
public class findarea_class {

    public static void main(String[] args)
    {
        findarea_class objtostring = new findarea_class(1.0,1.0);
        objtostring.setelements();
    }

    double width;
    double height;
    Scanner input = new Scanner(System.in);

    findarea_class()
    {

    }
    findarea_class(double width,double height)
    {
        this.width = width;
        this.height = height;

    }
    public String toString()
    {
        return "width is: "+this.width+" and height is: "+this.height+"\n"
                +"The area is : "+getarea(width,height)+"\n"
                +"The perimeter is: "+getperimeter(width,height);
    }

    double getarea(double width,double length)
    {
        double area = width * length;
        return area;
    }
    double getperimeter(double width,double length)
    {
        double perimeter = (2 * length) + (2 * width);
        return perimeter;
    }
    double getwidth()
    {
        System.out.println("Please the width for calculation:");
        double inputwidth = input.nextDouble();
        System.out.println("Width is:"+inputwidth);
        return inputwidth;
    }
    double getheight()
    {
        System.out.println("Please enter the height for calculation:");
        double inputheight = input.nextDouble();
        System.out.println("Height is:"+inputheight);
        return inputheight;
    }
    void setelements()
    {
        double newwidth;
        double newheight;

        newwidth = getwidth();
        newheight = getheight();

        System.out.println("The new area is : "+getarea(newwidth,newheight));
        System.out.println("The new perimeter is `enter code here`: "+getperimeter(newwidth,newheight));
    }
}

Answer 1

你没有调用toString（）。将它传递给任何可以显示它的东西。使用：

System.out.println(objtostring.toString());

Answer 2

你的主要方法应该打印对象，或者你可以把println调用放在你的构造函数中（虽然我不是那个人的忠实粉丝）。

public static void main(String[] args)
{
    findarea_class objtostring = new findarea_class(1.0,1.0);
    System.out.println(objtostring);
    objtostring.setelements();
}

Answer 3

您正试图覆盖toString类的Object方法。试试这个。

@Override    
public String toString() {
        return "width is: "+this.width+" and height is: "+this.height+"\n"
                +"The area is : "+getarea(width,height)+"\n"
                +"The perimeter is: "+getperimeter(width,height);
}

并将其称为objectName.toString();。在这种情况下，请使用类似的内容。objtostring.toString();

toString方法没有调用。 java的

3 个答案: