Java 使用字符串继续执行if/else语句（是或否）

您好，我刚开始用Java编程，即使在做了很多研究之后，我似乎也不知道如何以我理解的方式来完成。目前，当有人回答“你想要其他圆圈的面积吗？”时，有三种选择：A）是B）否C）任何东西。当你回答“不”时，它工作得很好。当你输入随机字符时，它会要求你说是或否，在这一点上回答“否”很好，但类似于A。当我回答“是”时，它会上升到找到圆的面积并询问你是否想要其他圆的面积。这是我想知道我是否可以使程序永远继续，直到用户输入“否”。如果有人能检查一下并告诉我我能做什么，那将非常有帮助，请记住我对Java的了解很少。谢谢

---

编辑：谢谢大家的帮助，我打电话给我的一个朋友，他向我解释了一切。我很感激你们为我所做的一切：）

你们可以使用

do{}while

来简化你们的代码-

// SquaresIn program 
import java.util.Scanner;
import java.lang.Math;
public class AreaInv2{

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

  System.out.println ("Hi there! What's your name?"); 
  String name = sc.next();

  System.out.println("Alright , " + name + ", enter the radius of the circle:");
  float radius = sc.nextFloat();

  float area = (float)(Math.pow(radius, 2) * Math.PI);
  System.out.print("The area is ");
  System.out.printf("%.2f", area);
  System.out.println(". Would you like the area of any other circles?");

  String yesno;
  yesno = sc.next();
  {
      if (yesno.equalsIgnoreCase("yes"))
          {
              System.out.println("Alright , " + name + ", enter the radius of the circle:");
              radius = sc.nextFloat();

              area = (float)(Math.pow(radius, 2) * Math.PI);
              System.out.print("The area is ");
              System.out.printf("%.2f", area);
              System.out.print(" square units.");
              System.out.println(" Would you like the area of any other circles?");
          }
      else if (yesno.equalsIgnoreCase("no"))
          {
              System.out.print("Have a great day " + name + "!");
              sc.close();

          }
      else
      {
          System.out.println("Sorry, could you say yes or no?");
          yesno = sc.next();
          if (yesno.equalsIgnoreCase("yes"))
          {
              System.out.println("Alright , " + name + ", enter the radius of the circle:");
              radius = sc.nextFloat();

              area = (float)(Math.pow(radius, 2) * Math.PI);
              System.out.print("The area is ");
              System.out.printf("%.2f", area);
              System.out.print(" square units.");
              System.out.println(" Would you like the area of any other circles?");
          }
      else if (yesno.equalsIgnoreCase("no"))
          {
              System.out.print("Have a great day " + name + "!");
              sc.close();
      }
      }   
  }
 }
}

---

如果您希望在满足给定条件的情况下运行某个程序，那么必须使用循环。在Java中，我们有三种类型的循环，do-while循环、while循环和for循环

在您的情况下，您应该使用do while，因为您需要在检查条件之前至少运行一次

请尝试下面的代码，希望它能帮助您

Scanner sc = new Scanner(System.in);

System.out.println("Hi there! What's your name?");
String name = sc.next();

String yesno = null;
do {
    System.out.printf("Alright %s, enter the radius of the circle: ",
            name);

    float radius = sc.nextFloat();
    float area = (float) (Math.pow(radius, 2) * Math.PI);
    System.out.printf("The area is %.2f. Would you like "
            + "the area of any other circles?", area);
    yesno = sc.next();
    while (!yesno.equalsIgnoreCase("yes")
            && !yesno.equalsIgnoreCase("no")) {
        System.out.println("Sorry, could you please say yes or no?");
        yesno = sc.next();
    }
} while (yesno.equalsIgnoreCase("yes"));
System.out.printf("Have a great day %s!%n", name);

---

它与您的代码几乎相同，我只是添加了循环，并将您的条件放在那里。

最好将代码组织在可重用函数中，以使其更具可读性：

import java.util.Scanner;

public class AreaInv2 {

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

        System.out.println("Hi there! What's your name?");
        String name = sc.next();
        String yesno;
        do {
            System.out.println("Alright , " + name + ", enter the radius of the circle:");
            float radius = sc.nextFloat();   
            float area = (float) (Math.pow(radius, 2) * Math.PI);

            System.out.print("The area is ");
            System.out.printf("%.2f", area);
            System.out.println(". Would you like the area of any other circles?");
            yesno = sc.next();

            while ((!(yesno.equalsIgnoreCase("yes") || yesno.equalsIgnoreCase("no")))) {
                System.out.println("Sorry, could you say yes or no?");
                yesno = sc.next();
            }
        } while (yesno.equalsIgnoreCase("yes"));

        System.out.print("Have a great day " + name + "!");
        sc.close();                
    }
}

---

好的，如果您希望某些事情继续（而不是结束）直到某些特定条件发生，您应该使用循环<代码>while，

do while

，

for

是java中的三种方法

public class AreaInv2 {

    private static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {

        String name = getName();
        while (true) {
            float radius = getRadius(name);
            printArea(radius);
            System.out.println("Would you like the area of any other circles? ");
            if (!needToDoAgain()) {
                System.out.print("Have a great day " + name + "!");
                break;
            }
        }
        sc.close();
    }

    private static String getName() {
        System.out.println("Hi there! What's your name?");
        return sc.next();
    }

    private static float getRadius(String name) {
        System.out.println("Alright , " + name + ", enter the radius of the circle: ");
        return sc.nextFloat();
    }

    private static void printArea(float radius) {
        float area = (float) (Math.pow(radius, 2) * Math.PI);
        System.out.print("The area is ");
        System.out.printf("%.2f", area);
        System.out.println(".");
    }

    private static boolean needToDoAgain() {
        String yesno = sc.next();
        if (yesno.equalsIgnoreCase("yes")) {
            return true;
        } else if (yesno.equalsIgnoreCase("no")) {
            return false;
        } else {
            System.out.println("Sorry, could you say yes or no? ");
            return needToDoAgain();
        }
    }
}

---

阅读do while循环。或者尝试在这里搜索。类似的问题已经被问过很多次了。你需要在这里使用循环，在你的情况下使用do while loops更好既然你在做方法，为什么不把

name

作为一个实例变量，这样你就不会把它传给你的方法了

getRadius（字符串名）

对我来说没有多大意义。@J.Lucky你说得对，但name实际上不是一个实例变量。在本例中，程序只获得一次名称，但它可能会在每次循环迭代中更改以获得名称…递归代替迭代的有趣用法。嗨，这是一群人中唯一一个我实际上能够理解的响应代码。你能解释一下while（！（yesno.equalsIgnoreCase（“yes”）| | yesno.equalsIgnoreCase（“no”）{System.out.println（“对不起，你能说是还是否？”）；yesno=sc.next（）；部分吗？| |和感叹号是什么意思？它有什么作用（代码块）while yesno=yes只要他们回答，就说继续循环那个部分？更新：我刚打电话给一个朋友，让他解释你写的代码，现在我明白了！谢谢！@gmitra，嘿，很抱歉昨天没能回复。我没有上网。总之，我很高兴这对你有用。谢谢你接受了答案。

        Scanner sc = new Scanner(System.in);

        System.out.println("Hi there! What's your name?");
        String name = sc.next();

        System.out.println("Alright , " + name
                + ", enter the radius of the circle:");
        float radius = sc.nextFloat();

        float area = (float) (Math.pow(radius, 2) * Math.PI);
        System.out.print("The area is ");
        System.out.printf("%.2f", area);
        System.out.println(". Would you like the area of any other circles?");
        String yesno = null;

        yesno = sc.next();

        while (!yesno.equalsIgnoreCase("no")) {

            if (yesno.equalsIgnoreCase("yes")) {

                System.out.printf(
                        "Alright %s, enter the radius of the circle: ", name);

                radius = sc.nextFloat();
                area = (float) (Math.pow(radius, 2) * Math.PI);
                System.out.printf("The area is %.2f. Would you like "
                        + "the area of any other circles?", area);

            } else {

                System.out.println("Sorry, could you please say yes or no?");
            }
            yesno = sc.next();
        }

        sc.close();

        System.out.printf("Have a great day %s!%n", name);