Question

当我执行下面的代码时，它会正确地为inputCar1方法输入输入，但在inputCar2方法中它会执行除第一个扫描程序命令之外的所有操作。如果我使用这个命令两次然后它就像我期望的那样工作，但它不应该。为了更好地理解我的问题，我附上了我的代码和输出。

PrintClass：

package TestPackage;

/**
 * Created by km.muzahid on 03-May-15.
 */
public class PrintClass {
    public static void print(Object value){
        System.out.print(value);
    }
    public static void println(Object value)
    {
        System.out.println(value);
    }
}

CarClass：

 package TestPackage;

    /**
 * Created by km.muzahid on 03-May-15.
 */
public class CarClass {
    public String manufacturerName;
    public int CarCC;
    public float CarWeight;
    public float FuealAmount;
    public CarClass()//constructor
    {
        CarCC=0;
        CarWeight=0;
        FuealAmount=0;
    }
    public CarClass(String CarNumber,String Name,int cc,float fuel,float weight)//constructor
    {
        PrintClass ShowMassage=new PrintClass();
        ShowMassage.println(CarNumber +"Car Manufacturer Name : "+Name+"\nCC of Car : "
                +cc+"\nAmount of fuel of car : "+fuel+"\nWeight of car : "+weight);
    }
}

问题代码：

package TestPackage;
import java.util.Scanner;
/**
 * Created by km.muzahid on 03-May-15.
 */
public class testclass {
    static private PrintClass ShowMassage;
    public static Scanner MyScanner=new Scanner(System.in);
    public static CarClass car=new CarClass();
    public static CarClass car2nd=new CarClass();//create new object from carclass for 2nd car

    public static void main(String[] args)
    {
      //1st car
       inputCar1("Enter for first car: ");
        CarClass SeeCar1=new CarClass("1st car details: \n",car.manufacturerName,car.CarCC,car.FuealAmount,car.CarWeight);
//        //2nd car
      CarClass See=new CarClass("2nd car details: \n",car2nd.manufacturerName,car2nd.CarCC,car2nd.FuealAmount,car2nd.CarWeight);

    }
    protected static void inputCar1(String Massege)
    {
        ShowMassage.println(Massege);
        ShowMassage.println("Enter Name of car manufactueing : ");
        car.manufacturerName=MyScanner.nextLine();
        ShowMassage.println("Enter weight of car :");
        car.CarWeight=MyScanner.nextFloat();
        ShowMassage.println("Enter the amount of Fuel : ");
        car.FuealAmount= MyScanner.nextFloat();
        ShowMassage.println("Enter the car CC : ");
        car.CarCC= MyScanner.nextInt();
        inputCar2("Enter For 2nd Car : ");
    }
    protected static void inputCar2(String Massege)
    {
        ShowMassage.println(Massege);
        ShowMassage.println("Enter Name of car manufactueing : ");
       //car2nd.manufacturerName=MyScanner.nextLine();
        car2nd.manufacturerName=MyScanner.nextLine();//problem indicated
        ShowMassage.println("Enter weight of car 2nd  :");
        car2nd.CarWeight=MyScanner.nextFloat();
        ShowMassage.println("Enter the amount of Fuel 2nd : ");
        car2nd.FuealAmount= MyScanner.nextFloat();
        ShowMassage.println("Enter the car 2nd  CC : ");
        car2nd.CarCC= MyScanner.nextInt();
        CarClass SeeCar1=new CarClass("1st car details: \n",car.manufacturerName,car.CarCC,car.FuealAmount,car.CarWeight);
        //2nd car
        CarClass See=new CarClass("2nd car details: \n",car2nd.manufacturerName,car2nd.CarCC,car2nd.FuealAmount,car2nd.CarWeight);
    }
}

输出：

Enter for first car: 
Enter Name of car manufactueing : 
lamborghini
Enter weight of car :
2222
Enter the amount of Fuel : 
2.369
Enter the car CC : 
236
Enter For 2nd Car : 
Enter Name of car manufactueing : 
Enter weight of car 2nd  :
263
Enter the amount of Fuel 2nd : 
3
Enter the car 2nd  CC : 
56
1st car details: 
Car Manufacturer Name : lamborghini
CC of Car : 236
Amount of fuel of car : 2.369
Weight of car : 2222.0
2nd car details: 
Car Manufacturer Name : 
CC of Car : 56
Amount of fuel of car : 3.0
Weight of car : 263.0
1st car details: 
Car Manufacturer Name : lamborghini
CC of Car : 236
Amount of fuel of car : 2.369
Weight of car : 2222.0
2nd car details: 
Car Manufacturer Name : 
CC of Car : 56
Amount of fuel of car : 3.0
Weight of car : 263.0

Answer 1

问题在于，当您按ENTER键时，您会向输入缓冲区发送一个新行（'\n'），当您执行car.CarCC= MyScanner.nextInt();时，它将使用数字而不是新行。所以稍后，当您执行car2nd.manufacturerName=MyScanner.nextLine();时，'\n'仍在输入缓冲区中，nextLine()将使用'\n'并立即返回空字符串。

解决方法是在这两行之间放置一个MyScanner.nextLine();以消耗丢失的新行。

第二种方法扫描仪不起作用

1 个答案: