Question

当获取main()函数中的输入时......字符串对象instSet的输入被跳过....有人可以解释为什么会发生这种情况以及如何纠正...现在我只是封闭了我的公共课。如果需要，以后添加其他类...

import java.util.Scanner;

public class MarsRover {

    private String inst_set;
    private Plateau p;
    private Cell currentLocation;

    public enum Direction{N,S,E,W}

    Direction dir;

    public MarsRover(Plateau p1, int x, int y, Direction dir, String instSet) {

        p=p1;
        inst_set=instSet;
        this.dir=dir;
        currentLocation=new Cell(x, y);


    }


    public void executeInst() {

        int i = 0;
        System.out.println(inst_set.length());
        while (i < inst_set.length()) {

            //System.out.println("Check");
            char inst = inst_set.charAt(i++); //get each inst seperately as a character

            if (inst=='M') {
                Cell temp=p.getNeighbour(dir, currentLocation);

                if (temp != null)
                     currentLocation=temp;

                else
                    continue;

            }

            if(inst=='L'||inst=='R'){

                dir=setDirection(dir,inst);

            }
        }



    }

    private Direction setDirection(Direction dir, char inst) {

        if(inst=='L') {
            switch (dir) {
                case N:
                    dir = Direction.W;
                    break;
                case W:
                    dir = Direction.S;
                    break;
                case S:
                    dir = Direction.E;
                    break;
                case E:
                    dir = Direction.N;
                    break;
            }

        }

        else if(inst=='R'){

            switch (dir) {
                case N:
                    dir = Direction.E;
                    break;
                case W:
                    dir = Direction.N;
                    break;
                case S:
                    dir = Direction.W;
                    break;
                case E:
                    dir = Direction.S;
                    break;
            }

        }

        return dir;

    }




    public static void main(String... a){

        Plateau p1=new Plateau();
        Scanner in = new Scanner(System.in);

        int x,y;
        String instSet;

        System.out.println("Enter the Initial XLocation:");
        x=in.nextInt();
        System.out.println("Enter the Initial YLocation:");
        y=in.nextInt();

        System.out.println("Enter the Instructions");
        instSet=in.nextLine();

        String dir;
        System.out.println("Enter the direction the rover is Headed");
        dir=in.nextLine();

        MarsRover mr1=new MarsRover(p1,x,y,Direction.valueOf(dir),instSet);
        mr1.executeInst();


    }

}

Answer 1

简单解决方案： 你应该简单地致电

instSet=in.next() + in.nextLine();

而不是

in.nextLine()

next（）从标准输入返回第一个令牌。 nextLine（）返回此标记后的下一行。

另一种解决方案： 每个nextInt（）之后的nextLine（），如下所示

    System.out.println("Enter the Initial XLocation:");
    x=in.nextInt();
    in.nextLine();
    System.out.println("Enter the Initial YLocation:");
    y=in.nextInt();
    in.nextLine();
    System.out.println("Enter the Instructions\t");
    instSet=in.nextLine();

如果您使用Scanner＃next ###（）（nextLine除外），并且当用户按Enter键时您到达行尾令牌，如果您不处理行尾令牌，它将阻止Scanner对象正常工作。因此，nextInt（）不读取并且正在由nextLine（）

读取

希望它澄清

火星探测器项目

1 个答案: