Question

在学习.Net之后，我决定亲自动手学习Java。在重新创建我的Hello World之后，我决定制作一个可能用途有限的程序。它似乎运行得很好，直到我给它选项重新启动input.nextline()似乎完全被忽略，它只是无限循环。下面我提交我的小程序，旨在帮助我女儿的数学。

package sndgrdmth;

import java.util.Scanner;
import java.util.Random;

public class sndgrd {
public static void main(String[] args) {
    Boolean bool = true;
    Scanner input = new Scanner(System.in);
    Random rand = new Random();
    while (bool == true) {

        System.out.println("Enter the highest number to add with:");
        String str = input.nextLine();

        while (isNum(str) == false) {
            System.out
            .println("Not a valid number.\rEnter your high number:");
            str = input.nextLine();
        }

        int i = Integer.parseInt(str);
        int counter = 0;
        int topCounter = 5;

        while (counter < topCounter) {
            int a = rand.nextInt(i);
            int b = rand.nextInt(i);
            System.out.println(a + " + " + b + " = ?");
            int j = input.nextInt();

            if (j == a + b) {
                ++counter;
                System.out.println("Correct Answer " + counter + " of "
                        + topCounter + "!!!");
            } else {
                --counter;
                System.out.println("Incorrect Answer " + a + " + " + b
                        + " = " + (a + b) + "\rLose one point.");
            }
        }
        System.out.println("Congrats! You Win! Do you want to play again? (Y/N)");
//The next line seems to get skipped.
        String repeat = input.nextLine();

        if ((repeat == "N") || (repeat == "n")) {
            bool = false;
        }else{
            bool = true;
        }
    }
    input.close();
}

public static boolean isNum(String strNum) {
    boolean ret = true;
    try {

        Double.parseDouble(strNum);

    } catch (NumberFormatException e) {
        ret = false;
    }
    return ret;
}
}

Answer 1

而不是使用nextLine()使用next()，这是因为在使用input.nextInt();得到测试的最后一个int后，它只会使用int而不是'\n' input.nextLine();因此，当您致电nextLine()时，它将消耗'\ n'，然后继续下一段代码。

<强>溶液

将您的所有next()更改为{{1}}。

扫描程序在程序结束时获取用户输入的问题

1 个答案: