问题描述

Java INPUT 语句的奇怪状况

以下是我在完成老师作业时候遇上的问题,希望能够得到解答,感谢!(问题在中间的comment里面描述)

public static void main(String[] args) {
//construct the first flight object
Scanner input=new Scanner(System.in);
System.out.println("Please enter the information regarding the first flight");
System.out.println("Please enter the flight number:");
String number = input.nextLine();
System.out.println("Please enter the origin of the flight:");
String origin = input.nextLine();
System.out.println("Please enter the destination of the flight");
String destination = input.nextLine();
System.out.println("Please enter the departure time in hh:mm format");
Time time=new Time(input.nextLine());
System.out.println("Please enter the length of the flight in minutes");
int length = input.nextInt();
flight first=new flight(number,origin,destination,time,length); 

//运行到此处,下面第一条获取number2的code没有运行,直接运行的第二条获取origin2的code,为什么?
System.out.println("Please enter the flight number:");
String number2 = input.nextLine();
System.out.println("Please enter the origin of the flight:");
String origin2 = input.nextLine();
System.out.println("Please enter the destination of the flight");
String destination2 = input.nextLine();
System.out.println("Please enter the departure time in hh:mm format");
Time time2=new Time(input.nextLine());
System.out.println("Please enter the length of the flight in minutes");
int length2 = input.nextInt();
flight second=new flight(number2,origin2,destination2,time2,length2);

解决方案

经测试，可行。
结果如下：

解决方案二：

nextInt()读入一个整型字符，不读入'n';
nextInt读入一行文本，读入'n'，但'n'不会成为返回的字符串的一部分。
int length=input.nextInt();
你在输入数字的时候，会输入“数字+回车”，这时候，数字部分就又input.nextInt()获取，而回车（相当于'n'）就会由下一个input.nextLine()获取。
这样就造成了“跳过”这行（String number2=input.nextLine()）的假象。其实并没有跳过，只不过输入了空行。测试如下：
package org.tarena.test;

import java.sql.Time;
import java.util.Scanner;

public class Test {

public static void main(String[] args) {
    //construct the first flight object
    Scanner input=new Scanner(System.in);
    System.out.println("Please enter the information regarding the first flight");
    System.out.println("Please enter the flight number:");
    String number = input.nextLine();
    System.out.println("Please enter the origin of the flight:");
    String origin = input.nextLine();
    System.out.println("Please enter the destination of the flight");
    String destination = input.nextLine();
    System.out.println("Please enter the departure time in hh:mm format");
    //Time time=new Time(input.nextLine());
    System.out.println("Please enter the length of the flight in minutes");
    int length = input.nextInt();
    //flight first=new flight(number,origin,destination,time,length); 

    //运行到此处,下面第一条获取number2的code没有运行,直接运行的第二条获取origin2的code,为什么?
    System.out.println("Please enter the flight number:");
    String number2 = input.nextLine();
    System.out.println("Please enter the origin of the flight:");
    String origin2 = input.nextLine();

// System.out.println("Please enter the destination of the flight");
// String destination2 = input.nextLine();
// System.out.println("Please enter the departure time in hh:mm format");
// Time time2=new Time(input.nextLine());
// System.out.println("Please enter the length of the flight in minutes");
// int length2 = input.nextInt();
// flight second=new flight(number2,origin2,destination2,time2,length2);
System.out.println(number+","+origin+","+destination+","+length+","+number2+","+origin2);
System.out.println(number2);
System.out.println(origin2);
}
}

依次输入1，2，3，4，5结果为：

解决方案三：

程序可以这么改，在int length=input.nextInt();下面加这行input.nextLine();让他去接收那个换行即可。
部分代码如下：