java - 实例变量没有在方法中被调用

Question

如果输入正确，我想在运行时调用区域实例变量以在Setter方法中显示其值。我正在使用 TriangleTester 来测试 Triangle 类。我只想根据所需的输出计算三角形的面积和周长

Triangle.java

import java.util.Scanner;
class Triangle 
{
private int a,b,c;  //sides of the triangle 
private double s,area;  //and 's' for the Heron's Formula
private int peri;
String type=new String();

Triangle()
{
    System.out.println("*****A Java Application To Determine Triangle and Comupute*****");
    setter();   
}



public void inputAndDetermine()
{
    if(((a+b)>c)&&((a+c)>b)&&((b+c)>a))
    {   
        determineType();
        calculatePerimeter();
        calculateArea();
        displayResult();    
    }
    else
    {
        System.out.println("The input doesn't describe a triangle");
    }        
}       

public void determineType()
{
    if((a==b)&&(a==c))
    {
        type="Equilateral triangle";
    }
    else if((a==b)||(b==c)||(a==c))
    {
        type="Isoceles triangle";           
    }
    else
    {
        type="Scalene triangle";
    }
}

public void calculatePerimeter()
{
    peri=a+b+c;
}   

public strictfp void calculateArea()
{
    s=(a+b+c)/2;
    area=(Math.sqrt((s*(s-a)*(s-b)*(s-c))));        
}

public void displayResult()
{
System.out.println("\t Summary of Computing Triangle Perimeters & Areas \t");
System.out.println("----------------------------------------------------------");
System.out.println("\t Sides(a,b,c) \t Perimeter \t Area \t    Type \t");   
System.out.println("----------------------------------------------------------");
System.out.println("\t   " + a + " " + b + " " +  c + "\t    " + peri + "\t    " + area + "\t" + type );
System.out.println("");
System.out.println("");
System.out.println("Bar Chart Of Number of Triangle Constructed");
}

public void setter()
{
    Scanner keyboard = new Scanner(System.in);
    System.out.print("Enter the length of 1st side of Triangle 1 :  ");
    this.a=keyboard.nextInt();
    System.out.print("Enter the length of 1st side of Triangle 1 :  ");
    this.b=keyboard.nextInt();
    System.out.print("Enter the length of 1st side of Triangle 1 :  ");
    this.c=keyboard.nextInt();
    System.out.println("The Triangle perimeter and area are :");
    System.out.println("\t \t" + peri + " unit, " + area + " units. " + type );
    System.out.println("-----------------------------------------------------------");
}

}

TriangleTester.java

class TriangleTester
{
public static void main(String [] ar)
{
    Triangle tri = new Triangle();
    tri.inputAndDetermine();
}
}

这是我得到的输出

Output Of the program

Answer 1

将setter方法代码更改为

...
this.c=keyboard.nextInt();
// add these two lines
calculatePerimeter();
calculateArea();

System.out.println("The Triangle perimeter and area are :");
System.out.println("\t \t" + peri + " unit, " + area + " units. " + type );
System.out.println("-----------------------------------------------------------");

但这似乎毫无意义。