请求文件名作为输入--java

Question

我此刻代码：

import java.util.*; 
import java.io.*; 

public class Percolation { 
    // given an N-by-N matrix of open sites, return an N-by-N matrix 
    // of sites reachable from the top via a vertical path of open sites 
    private static Scanner scan = null; 

    public static boolean[][] readOpenFromFile() { 
     final File f = new File("file.txt"); 
     try { 
      scan = new Scanner(f); 
     } 
     catch(FileNotFoundException ex) { 
      System.exit(0); 
     } 

     final int m = scan.nextInt(); 
     final int n = scan.nextInt(); 
     final boolean[][] grid = new boolean[m][n]; 

     for(int i = 0; i < m; i++) { 
      for(int j = 0; j < n; j++) { 
       grid[i][j] = readBoolean(); 
      } 
     } 
     return grid; 
    } 

    public static boolean readBoolean() { 
     final String s = scan.next(); 

     if(s.equalsIgnoreCase("true")) { 
      return true; 
     } 
     if(s.equalsIgnoreCase("false")) { 
      return false; 
     } 
     if(s.equals("1")) { 
      return true; 
     } 
     if(s.equals("0")) { 
      return false; 
     } 
     throw new java.util.InputMismatchException(); 
    } 

    public static boolean[][] flow(final boolean[][] open) { 
     final int n = open.length; 
     final boolean[][] full = new boolean[n][n]; 
     for(int j = 0; j < n; j++) { 
      flow(open, full, 0, j); 
     } 
     return full; 
    } 

    public static void flow(final boolean[][] open, final boolean[][] full, final int i, final int j) { 
     final int n = open.length; 

     // base cases 
     if((i < 0) ||(i >= n)) { 
      return; // invalid row 
     } 
     if((j < 0) ||(j >= n)) { 
      return; // invalid column 
     } 
     if(!open[i][j]) { 
      return; // not an open site 
     } 
     if(full[i][j]) { 
      return; // already marked as full 
     } 

     // mark i-j as full 
     full[i][j] = true; 

     flow(open, full, i + 1, j); // down 
     flow(open, full, i, j + 1); // right 
     flow(open, full, i, j - 1); // left 
     flow(open, full, i - 1, j); // up 
    } 

    // does the system percolate? 
    public static boolean percolates(final boolean[][] open) { 
     final int n = open.length; 
     final boolean[][] full = flow(open); 
     for(int j = 0; j < n; j++) { 
      if(full[n - 1][j]) { 
       System.out.println("percolates"); 
       return true; 
      } 
     } 
     System.out.println("does not percolate"); 
     return false; 
    } 

    public static void print(final boolean[][] grid) { 
     final int m = grid.length; 
     final int n = grid[0].length; 
     System.out.println(m + " " + n); 
     for(int i = 0; i < m; i++) { 
      for(int j = 0; j < n; j++) { 
       if(grid[i][j]) { 
        System.out.print("1 "); 
       } else { 
        System.out.print("0 "); 
       } 
      } 
      System.out.println(""); 
     } 
    } 

    public static void main(String[] args) { 
     final boolean[][] open = readOpenFromFile(); 
     print(flow(open)); 
     System.out.println(percolates(open)); 
    } 
} 

可以看出，这个程序的工作原理是从file.txt的文件抓取输入。然而，我怎么修改这个代码以便请求要求每次程序运行时都有一个文件名（可能在命令行），并且使用那作为输入？ 我想添加一个字符串作为参数，然后将该字符串更改为文件名。但说起来容易做起来难。建议？

Answer 1

你可以把它作为一个参数和修改代码 -

public static void main(String[] args) { 
    // args[0] - Full path of the file 
    final boolean[][] open = readOpenFromFile(args[0]); 
    print(flow(open)); 
    System.out.println(percolates(open)); 
} 

public static boolean[][] readOpenFromFile(String filepath) { 
    final File f = new File(filepath); 
    try { 
     scan = new Scanner(f); 
    } 
    catch(FileNotFoundException ex) { 
     System.exit(0); 
    } 

    final int m = scan.nextInt(); 
    final int n = scan.nextInt(); 
    final boolean[][] grid = new boolean[m][n]; 

    for(int i = 0; i < m; i++) { 
     for(int j = 0; j < n; j++) { 
      grid[i][j] = readBoolean(); 
     } 
    } 
    return grid; 
} 

Answer 2

您可以使用此代码：

public static boolean[][] readOpenFromFile(String file) { 
    final File f = new File(file); 
    // same code ... 
} 


public static void main(String[] args) { 
    if(args != null && args.length == 1) { 
     String file = args[0];  

     final boolean[][] open = readOpenFromFile(file); 
     print(flow(open)); 
     System.out.println(percolates(open)); 
    } 
} 

Answer 3

你需要这样的事情，但你必须添加检查文件名：

InputStreamReader converter = new InputStreamReader(System.in); 
     BufferedReader in = new BufferedReader(converter); 


     while (!(CurLine.equals("quit"))){ 
      CurLine = in.readLine(); 

      if (!(CurLine.equals("quit"))){ 
       System.out.println("You typed: " + CurLine); 
      } 
     } 

Link to site where you can find it