传入args[]或缺少java中的args

Question

我正在为课堂上的作业编写代码，从来没有这样使用过扫描仪。然而，当我读取下面的代码时，我会得到以下错误

Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:862)
at java.util.Scanner.next(Scanner.java:1485)
at java.util.Scanner.nextInt(Scanner.java:2117)
at java.util.Scanner.nextInt(Scanner.java:2076)
at World.<init>(World.java:20)
at World.main(World.java:58)

我想我只是有点困惑，因为我使用world文本文件创建了eclipse，它只是不允许这样做。

   import java.util.Scanner;

 /*************************************************************************
* Name        :  
* Username    : 
* Description :      *************************************************************************/

 public class World{
//instance variables
String mapFile; //This holds the .txt name that contains the map.
Tile[][] worldMap;

public World(String mapFile){
    this.mapFile = mapFile;

    Scanner scanner = new Scanner(mapFile);
    //get the dimensions of the world
    int width = scanner.nextInt();
    int height = scanner.nextInt();
    int x_coor = scanner.nextInt();
    int y_coor = scanner.nextInt();
    //initialize the array to proper height and width
    worldMap = new Tile[width][height];
    //set the starting locations of the avatar character
    Avatar avatar = new Avatar(x_coor, y_coor);
    //populate the worldMap
    for(int i = 0; i < worldMap.length - 1; i++){
        for(int j = 0; i <worldMap[0].length -1; j++){
            worldMap[i][j] = new Tile(scanner.next());
        }
    }


}
//draw the map
public void draw(){
    for(int i = 0; i < worldMap.length - 1; i++){
        for(int j = 0; j < worldMap[0].length -1; i++){
            worldMap[i][j].draw(i, j);
        }
    }
}







// Test method


public static void main(String [] args)
{       


    World world = new World(args[0]);
    world.draw();       
}   

}

Answer 1

您的Scanner是围绕一个String (而不是围绕一个File)构建的。改变这个

Scanner scanner = new Scanner(mapFile);

至

Scanner scanner = new Scanner(new File(mapFile));

现在，Scanner正在扫描您的String文件名。