Question

只需编写一个简单的程序，要求用户输入圆形，矩形或三角形。然后它要求他们对形状进行适当的测量，然后使用正确的方法计算这种形状的面积但是，只为矩形方法生成正确的答案无论输入什么，circle方法总是生成0.0，而三角形方法不会乘以0.5但只返回base * height。

提出了一些建议的更改，我仍然遇到同样的问题。这是完整的代码。

import java.util.Scanner;

public class Area{
public static void main(String[] args){
    Scanner myScanner = new Scanner(System.in);

    String shape = "";
    boolean notAcceptable = true;

    do {
        System.out.print("What kind of shape? ");
        shape = myScanner.next();
        if(shape.equals("circle") || shape.equals("triangle") || shape.equals("rectangle")){
            notAcceptable= false;
        }else{
            System.out.println("ERROR: Please input 'circle','rectangle' or 'triangle'.");
        }
    }while(notAcceptable);

    double radius = 0.0;
    double base = 0.0;
    double height = 0.0;
    boolean acceptable = false;
    boolean acceptable1 = false;
    boolean acceptable2 = false;

    if(shape.equals("circle")){
        System.out.print("Enter the radius of the circle: ");

        while( !acceptable ){
        //check if the input is a double.
        if (myScanner.hasNextDouble()){
        radius = myScanner.nextDouble();
        acceptable = true;
        break;
        }
        else{
        System.out.println("ERROR: Input must be a double");
        System.out.print("Enter the radius of the circle ");
        myScanner.next();
        }
        } 

    }else{
        System.out.print("Enter the height: ");
        while( !acceptable1 ){
        //check if the input is a double.
        if (myScanner.hasNextDouble()){
        height = myScanner.nextDouble();
        acceptable = true;
        break;
        }
        else{
        System.out.println("ERROR: Input must be a double");
        System.out.print("Enter the height: ");
        myScanner.next();
        }
        }

        System.out.print("Enter the length of the base: ");
        while( !acceptable2 ){
        //check if the input is a double.
        if (myScanner.hasNextDouble()){
        base = myScanner.nextDouble();
        acceptable = true;
        break;
        }
        else{
        System.out.println("ERROR: Input must be a double");
        System.out.print("Enter the length of the base: ");
        myScanner.next();
        }
        }
    }

    if(shape=="circle"){
        circleArea(radius);
    }else if (shape=="triangle"){
        triangleArea(base,height);
    }else{
        rectangleArea(base,height);
    }


}//bracket that closes main method

    public static void circleArea(double r){
        double areaC= 3.14*r*r;
        System.out.println("The area of your circle is "+areaC);
    }

    public static void rectangleArea(double b1, double h1 ){
        double areaR= b1*h1;
        System.out.println("The area of your rectangle is "+areaR);
    }

    public static void triangleArea(double b2, double h2){
        double areaT = 0.5*b2*h2;
        System.out.println("The area of your triangle is "+areaT);
    }


}//bracket that closes class

Answer 1

请记住，在比较Java中的Strings时，您需要使用equals方法。使用==，您正在执行reference comparison。

试试这个：

if(shape.equals("circle")) {
    circleArea(radius);
}else if (shape.equals("triangle")) {
    triangleArea(base,height);
} else {
    rectangleArea(base,height);
}

或者，为了防止空值并使其不区分大小写，大多数开发人员都会这样做：

if("circle".equalsIgnoreCase(shape) {
    circleArea(radius);
} else if ("triangle".equalsIgnoreCase(shape)) {
    triangleArea(base,height);
} else {
    rectangleArea(base,height);
}

因为您使用的是==，所以您总是会遇到正在计算矩形的else情况。

正如其他人所提到的，你的计算中也可能有错误。

Answer 2

首先，你实际上没有将三角形的面积乘以0.5，代码应为：

double area = b2*h2*0.5;
System.out.println("The area of your triangle is "+area);

同时检查您是否输入正确。请发布输入正确性的证明。

返回错误值的方法？

2 个答案: