Question

我对此比较陌生，任何帮助都会很棒。对于我的作业，我应该制作一个Triangle和TriangleTester类，使用扫描仪操作值，以找到三角形边，角度，周长等的长度。我不是要求你做我的作业但是可能指向我在正确的方向。这只是一小部分，但它让我无法继续。

我无法弄清楚的是如何让我输入的变量跨越方法（如果这是有道理的。

这是我的三角代码：

import java.math.*;
import java.util.Scanner;

public class Triangle
{
private double A, B, C, D, h;
public double x1, x2, x3, y1, y2, y3;
public double lengthA, lengthB, lengthC;
private double angleA, angleB, angleC;
private double calcPerimeter, calcArea, getHeight;

//Create new Triangle
public Triangle(){
}

//to get length of a (AB) use A = (x1, y1) & B = (x2,y2)
public double getLengthC(){
double distance = Math.sqrt((Math.pow((x1-x2),2))+(Math.pow((y1-y2),2)));
return distance;
}
}

这是我的TriangleTester代码：

import java.util.Scanner;

public class TriangleTester
{
public static void main(String[]args)
{
Triangle triangle1 = new Triangle();

Scanner scan = new Scanner(System.in);
System.out.println("Enter x1 for point A");
double x1 = scan.nextDouble();
System.out.println("Enter y1 for point A");
double y1 = scan.nextDouble();
System.out.println("Enter x2 for point A");
double x2 = scan.nextDouble();
System.out.println("Enter y2 for point A");
double y2 = scan.nextDouble();
System.out.println("Enter x3 for point A");
double x3 = scan.nextDouble();
System.out.println("Enter y3 for point A");
double y3 = scan.nextDouble();
System.out.println("Set up a Triangle with coordinates " +"("+x1+","+y1+")"+ ","+ "("+x2+","+y2+")" +","+ "("+x3+","+y3+")");

System.out.println("Length of side c " + triangle1.getLengthC());
}
}

出于测试目的，我想输入值：

并且将c的长度计算为4.我看到当我在TriangleTester类中使用变量时，变量可以工作，但是当我从Triangle类调用一个方法时，值不起作用。

从我所在的地方，我认为我必须操纵三角形类，以便我将来自扫描仪的输入移动到该区域......或者我可能是错的

public Triangle(){} //I would have to add something here maybe?

Answer 1

是的，你是对的。由于您在TriangleTester中获得了用户输入，因此需要将其传递给Triangle类。

public Triangle(double x1, double x2, double x3, double y1, double y2, double y3) {
    this.x1 = x1;
    this.x2 = x2;
    this.x3 = x3;
    this.y1 = y1;
    this.y2 = y2;
    this.y3 = y3;
}

在从用户获取值之后创建Triangle对象：

Triangle triangle1 = new Triangle(x1, x2, x3, y1, y2, y3);
System.out.println("Length of side c " + triangle1.getLengthC());

注意：建议您将班级的所有实例变量设为private，并为其提供正确的 getter和setter 。

Answer 2

Scanner中的问题不是。您永远不会填写Triangle triangle1变量中的字段，因此所有字段都有默认值，即0.0。

刚开始从变量填充字段。例如：

triangle1.x1 = x1;
//and on...

但这是一个不好的做法，最好将字段声明为private并使用setter作为作业，或者使用接受必要字段的构造函数。

class Triangle {
    private double x1, x2, x3, y1, y2, y3;
    public double getX1() {
        return this.x1;
    }
    public void setX1(double x1) {
        this.x1 = x1;
    }
    //other fields, getters and setters...
}

//...
//in your TriangleTester#main method
triangle1.setX1(x1);
//same for other fields...

Answer 3

您尚未使用从triangle

中读取的值设置Scanner的值

这可以作为构造函数的一部分来完成：

public Triangle (double x1, double x2, double x3, double y1, double y2, double y3) {
    this.x1 = x1;
    this.x2 = x2;
    this.x3 = x3;
    this.y1 = y1;
    this.y2 = y2;
    this.y3 = y3;
}

或者您可以在Traingle类上设置setter方法

void setX1 (double x1) 
{
    this.x1 = x1;
}

etc.

Answer 4

试试这个

import java.util.Scanner;

公共类MainClass {

public static void main(String[] args) {


    Scanner scan = new Scanner(System.in);
    System.out.println("Enter x1 for point A");
    double x1 = scan.nextDouble();
    System.out.println("Enter y1 for point A");
    double y1 = scan.nextDouble();
    System.out.println("Enter x2 for point A");
    double x2 = scan.nextDouble();
    System.out.println("Enter y2 for point A");
    double y2 = scan.nextDouble();
    System.out.println("Enter x3 for point A");
    double x3 = scan.nextDouble();
    System.out.println("Enter y3 for point A");
    double y3 = scan.nextDouble();
    System.out.println("Set up a Triangle with coordinates " +"("+x1+","+y1+")"+ ","+ "("+x2+","+y2+")" +","+ "("+x3+","+y3+")");

    Triangle triangle1 = new Triangle(x1,x2,y1,y2,x3,y3);
    System.out.println("Length of side c " + triangle1.getLengthC());

}

}

和

import java.math.*;
import java.util.Scanner;

public class Triangle
{
private double A, B, C, D, h;
public double x1, x2, x3, y1, y2, y3;
public double lengthA, lengthB, lengthC;
private double angleA, angleB, angleC;
private double calcPerimeter, calcArea, getHeight;

//Create new Triangle
public Triangle(double x1,double x2,double y1,double y2,double x3, double y3){
    this.x1=x1;
    this.y1=y1;
    this.x2=x2;
    this.y2=y2;
    this.x3=x3;
    this.y3=y3;
}

//to get length of a (AB) use A = (x1, y1) & B = (x2,y2)
public double getLengthC(){
double distance = Math.sqrt((Math.pow((x1-x2),2))+(Math.pow((y1-y2),2)));
System.out.println(distance);
return distance;
}
}

调用方法时，扫描程序输入不起作用

4 个答案: