Question

我正在用Java创建一个简单的项目来接收和显示大学名称。当我将值0输入到变量val时，它不允许我通过扫描仪接收输入。但我可以在使用val++时输入值。请查看我的代码并解释其背后的逻辑。具体来说，我遇到了if (val == 0)循环的问题。

package com.example.java;

import java.util.Scanner;

public class Main {

public static void main(String[] args) {
    System.out.println("Please click to enter your name: ");
    Scanner scn = new Scanner(System.in);
    String str = scn.nextLine();
    System.out.println("Ooh so your name is " + str);

    StringBuilder sb = new StringBuilder();

    System.out.println("How may universities are you expecting decisions from ");
    int val = scn.nextInt();

    if (val == 0) {
        val++;
        System.out.println("ooh nice. Enter the university you chose");
        for (int i = 0; i <= val; i++) {

            String waitlist = scn.nextLine();
            sb.append(waitlist);

        }
        val--;
        System.out.println("So you are going to "+sb +"!! congrats");

    }

    if (val >= 4) {
        System.out.println("Damnnn!! " + val + " universities!! that's pretty steep");
        System.out.println("Enter names of pending universities " + "\n");

        for (int i = 0; i <= val; i++) {

            String waitlist = scn.nextLine();
            sb.append(waitlist + "\n");

        }

        System.out.println("So you are waiting for the following universities: " +"\n");
        System.out.println(sb + "All the best mate!");

    } if (val < 4 && val != 0) {
        System.out.println("ooh so its just " + val + " universities, the decision should be just round the corner");
        System.out.println("Enter names of pending universities " + "\n");

        for (int i = 0; i <= val; i++) {

            String waitlist = scn.nextLine();
            sb.append(waitlist + "\n");

        }

        System.out.println("So you are waiting for the following universities: " +"\n");
        System.out.println(sb + "All the best mate!");

    }


    }
}

Answer 1

修复你的大学数量和你的for循环，这样的东西，仍然检查它：

    try (Scanner scn = new Scanner(System.in);) {

        System.out.println("Please click to enter your name: ");
        String str = scn.nextLine();
        System.out.println("Ooh so your name is " + str);

        System.out.println("How may universities are you expecting decisions from ");
        int val = scn.nextInt();
        scn.nextLine();

        // 0 or negative
        if (val <= 0) {
            // no universities... that's pretty pessimistic

        } else if (val == 1) {
            System.out.println("ooh nice. Enter the university you chose");
            String university = scn.nextLine();

            System.out.println();
            System.out.println("So you are going to " + university + "!! congrats");

        } else if (val < 4) {
            System.out.println("ooh so its just " + val
                    + " universities, the decision should be just round the corner");
            System.out.println("Enter names of pending universities: ");

            StringBuilder sb = new StringBuilder();
            // from i = 0 to i < val (NOT i <= val)
            // 0 to val would be val iterate val + 1 times
            for (int i = 0; i < val; i++) {
                String waitlist = scn.nextLine();
                sb.append(waitlist).append(System.lineSeparator());
            }

            System.out.println();
            System.out.println("So you are waiting for the following universities: ");
            System.out.println(sb);
            System.out.println("All the best mate!");

        } else if (val >= 4) {
            System.out.println("Damnnn!! " + val + " universities!! that's pretty steep");
            System.out.println("Enter names of pending universities: ");

            StringBuilder sb = new StringBuilder();
            // from i = 0 to i < val (NOT i <= val)
            // 0 to val would be val iterate val + 1 times
            for (int i = 0; i < val; i++) {
                String waitlist = scn.nextLine();
                sb.append(waitlist).append(System.lineSeparator());
            }

            System.out.println();
            System.out.println("So you are waiting for the following universities: ");
            System.out.println(sb);
            System.out.println("All the best mate!");
        }
    }
}

当我将值0输入到变量val时，它不允许我通过扫描仪接收输入

1 个答案: