为什么我不能在if语句后输入信息？没有错误显示

Question

如何让程序在if语句后使用扫描器请求输入？

import java.util.Scanner;

public class App1 {

    public static void main(String[] Args) {

        Scanner keyboard = new Scanner(System.in);

        String gender;
        String fName;
        String lName;
        int age;
        String female = "F";
        String male = "M";
        String a = "";
        String gettingMarried = "y";
        String notGettingMarried = "n";

        System.out.println("What is your gender (M or F)");
        gender = keyboard.nextLine();
        System.out.println("What is your first name?");
        fName = keyboard.nextLine();
        System.out.println("What is your last name?");
        lName = keyboard.nextLine();
        System.out.println("Age:");
        age = keyboard.nextInt();
        System.out.println();

        if (gender.equals(female) && age >= 20) {
            System.out.println("Are you married " + fName + " (y or n?)");
            a = keyboard.nextLine();

        } else if (gender.equals(male) && age >= 20) {
            System.out.println("Are you married" + fName + "(y or n?)");
            a = keyboard.nextLine();
        }

    }
}

Answer 1

这是因为您使用的nextint()只接受int值，而不是整行。当您再次尝试使用keyboard.nextline()读取您正在捕获的内容时，您将在其中放置int的行的其余句子。

将if语句前的system.out.println（）；更改为keyboard.nextline()；

编辑：如果您想要关于为什么必须在keyboard.nextline（）；之后放置keyboard.nextint()的更详细的解释，您可以参考我在另一个问题中的回答：为什么扫描仪输入不工作？