循环问题和将数据存储在变量中答案

【问题标题】：Trouble with loop and storing data in variables循环问题和将数据存储在变量中
【发布时间】：2026-02-07 04:55:01
【问题描述】：

我试图完成的程序需要从用户那里读取三个数字，然后将它们存储在变量num1、num2 和num3 中，以便它们可以在步骤 2 和 3 中使用。我遇到的问题是，当程序在用户输入他们的数字并尝试继续执行第 2 步或第 3 步后循环时，它说必须先完成第 1 步。
这是我现在的代码：

    static Scanner console = new Scanner(System.in);

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        int num1;
        int num2;
        int num3;
        int input;

        do {
            boolean opt1Done = false;
            System.out.println("Select your next step");
            System.out.println("1: Enter three numbers between 1 and 100.");
            System.out.println("2: Order your number in ascending order");
            System.out.println("3: Determine if the three inputs form a triangle");
            System.out.println("4: Exit");

            int answer = console.nextInt();
            num1 = console.nextInt();
            num2 = console.nextInt();
            num3 = console.nextInt();
            input = console.nextInt();

            if (answer == 1) {
                //do whatever for option 1
                System.out.println("Enter a value for num1 between 1 and 100.");
                System.out.println("Enter a value for num2 between 1 and 100.");
                System.out.println("Enter a value for num3 between 1 and 100.");

                opt1Done = true;
            } else if (answer == 2) {
                if (opt1Done) {
                    //...... do whatever to order the numbers
                    int[] arraynum;
                    arraynum = new int[3];

                    arraynum[0] = num1;
                    arraynum[1] = num2;
                    arraynum[2] = num3;

                    Arrays.sort(arraynum);

                    int i;

                    for (i = 0; i < arraynum.length; i++) {
                        System.out.println("num:" + arraynum[i]);
                    }

                } else {
                    System.out.println("you must complete Step 1 before Step 2");
                }
            } else if (answer == 3) {
                if (opt1Done) {
                    //... do whatever to determine if triangle or not
                    if (num1 + num2 > num3 && num1 + num3 > num2 && num2 + num3 > num1) {
                        System.out.print("TRIANGLE");
                    } else {
                        System.out.print("NO TRIANGLE");
                    }
                } else {
                    System.out.println("you must complete Step 1 before Step 3");
                }
                if (answer == 4) {
                    System.exit(0);

                }
            }
        } while (input != 4);
    }
}

我需要添加另一个循环还是更改已有的循环？

【问题讨论】：

似乎是它的功课。是吗？
它用于编程课程的项目是的@MuhammadSuleman
你又破解了密码！编辑问题时要小心；）
opt1Done 在每次迭代后被设置为 false，在你开始做之前移动 boolean opt1Done = false; ..while 循环

标签： java loops variables storing-data

【解决方案1】：

将布尔声明 opt1Done 和数字移到循环之外，并在每次用户提示后读取输入。

 import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Scanner;

public class ReadChar {

    public ReadChar() {
        // TODO Auto-generated constructor stub
    }

    static Scanner console = new Scanner(System.in);

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        int num1 = 0;
        int num2 = 0;
        int num3 = 0;
        boolean opt1Done = false;

        while (true) {

            System.out.println("Select your next step");
            System.out.println("1: Enter three numbers between 1 and 100.");
            System.out.println("2: Order your number in ascending order");
            System.out
                    .println("3: Determine if the three inputs form a triangle");
            System.out.println("4: Exit");

            int answer = console.nextInt();

            if (answer == 1) {
                // do whatever for option 1
                System.out.println("Enter a value for num1 between 1 and 100.");
                num1 = console.nextInt();

                System.out.println("Enter a value for num2 between 1 and 100.");
                num2 = console.nextInt();
                System.out.println("Enter a value for num3 between 1 and 100.");
                num3 = console.nextInt();

                opt1Done = true;
            } else if (answer == 2) {
                if (opt1Done) {
                    // ...... do whatever to order the numbers
                    int[] arraynum;
                    arraynum = new int[3];

                    arraynum[0] = num1;
                    arraynum[1] = num2;
                    arraynum[2] = num3;

                    Arrays.sort(arraynum);

                    int i;

                    for (i = 0; i < arraynum.length; i++) {
                        System.out.println("num:" + arraynum[i]);
                    }

                } else {
                    System.out
                            .println("you must complete Step 1 before Step 2");
                }
            } else if (answer == 3) {
                if (opt1Done) {
                    // ... do whatever to determine if triangle or not
                    if (num1 + num2 > num3 && num1 + num3 > num2
                            && num2 + num3 > num1) {
                        System.out.print("TRIANGLE");
                    } else {
                        System.out.print("NO TRIANGLE");
                    }

                } else {
                    System.out
                            .println("you must complete Step 1 before Step 3");
                }

            }
            if (answer == 4) {
                System.exit(0);

            }
        }
    }
}

【讨论】：

【解决方案2】：

您不会循环查看说明。每次你完成一个步骤，程序就会结束，下次你运行它时，你之前所做的一切都不会被保存。

您需要一个外部循环来迭代命令：

public static void main(String[] args) {

    int num1;
    int num2;
    int num3;

    boolean opt1Done = false;

    while (true) {

        System.out.println("Select your next step");
        System.out.println("1: Enter three numbers between 1 and 100.");
        System.out.println("2: Order your number in ascending order");
        System.out.println("3: Determine if the three inputs form a triangle");
        System.out.println("4: Exit");

        //rest of your code here
    }
}

【讨论】：

【解决方案3】：

您似乎必须循环直到用户选择选项 4。我没有看到任何包含问题选项的循环。

【讨论】：

【解决方案4】：

希望对你有帮助

引入了一个 while 循环，并且 opt1True 应该在循环之外

检查答案 4 在答案 3 中。因此，如果与其他答案检查处于同一水平，则将其移入 else 中

static Scanner console = new Scanner(System.in);

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        int num1 = 0;
        int num2 = 0;
        int num3 = 0;
        boolean opt1Done = false;
        while(true) {
        System.out.println("Select your next step");
        System.out.println("1: Enter three numbers between 1 and 100.");
        System.out.println("2: Order your number in ascending order");
        System.out.println("3: Determine if the three inputs form a triangle");
        System.out.println("4: Exit");

        int answer = console.nextInt();
        if (answer == 1) {
            // do whatever for option 1
            System.out.println("Enter a value for num1 between 1 and 100.");
            num1 = console.nextInt();

            System.out.println("Enter a value for num2 between 1 and 100.");
            num2 = console.nextInt();

            System.out.println("Enter a value for num3 between 1 and 100.");
            num3 = console.nextInt();

            opt1Done = true;
        } else if (answer == 2) {
            if (opt1Done) {
                // ...... do whatever to order the numbers
                int[] arraynum;
                arraynum = new int[3];

                arraynum[0] = num1;
                arraynum[1] = num2;
                arraynum[2] = num3;

                Arrays.sort(arraynum);

                int i;

                for (i = 0; i < arraynum.length; i++) {
                    System.out.println("num:" + arraynum[i]);
                }

            } else {
                System.out.println("you must complete Step 1 before Step 2");
            }
        } else if (answer == 3) {
            if (opt1Done) {
                // ... do whatever to determine if triangle or not
                if (num1 + num2 > num3 && num1 + num3 > num2
                        && num2 + num3 > num1) {
                    System.out.print("TRIANGLE");
                } else {
                    System.out.print("NO TRIANGLE");
                }
            } else {
                System.out.println("you must complete Step 1 before Step 3");
            }

        } else if (answer == 4) {
            System.exit(0);

        }

        }

    }

【讨论】：

【解决方案5】：

你把条件放在错误的地方。因为我在想首先检查用户的答案，然后将第一个条件中的这 3 个数字作为

int answer = console.nextInt();
    if (answer == 1) {
        //do whatever for option 1
        System.out.println("Enter a value for num1 between 1 and 100.");
        num1 = console.nextInt();
        System.out.println("Enter a value for num2 between 1 and 100.");
        num2 = console.nextInt();
        System.out.println("Enter a value for num3 between 1 and 100.");
        num3 = console.nextInt();
        opt1Done = true;
   }

并将这条线移到循环之外

 boolean opt1Done = false;

【讨论】：

【解决方案6】：

您所要做的就是在逻辑中添加一个 while 循环并重新排序。

    boolean opt1Done = false;
    int num1, num2, num3;
  while(answer != 4){


  System.out.println("Select your next step");
    System.out.println("1: Enter three numbers between 1 and 100.");
    System.out.println("2: Order your number in ascending order");
    System.out.println("3: Determine if the three inputs form a triangle");
    System.out.println("4: Exit");

    int answer = console.nextInt();


    if (answer == 1) {
        //do whatever for option 1
        System.out.println("Enter a value for num1 between 1 and 100.");
        num1 = console.nextInt();
        System.out.println("Enter a value for num2 between 1 and 100.");
        num2 = console.nextInt();
        System.out.println("Enter a value for num3 between 1 and 100.");
        num3 = console.nextInt();
    opt1Done = true;
  }

                                    ...


       if (answer == 4) {
                    System.exit(0);

                }
            }
         }
     }

您的问题是每次循环时，您都在重新声明布尔变量并将其设置为 false。再加上你的 console.nextInts() 是在错误的位置。在这种情况下也不需要做while，因为answer的起始值为null，因此不等于4。

【讨论】：