泛型和在實現Iterable接口的類中使用新創建的方法

Question

我正在研究一個檢查數獨解決方案的有效性的程序。我已經接近完成了，但由於某種原因，當我嘗試調用某些已創建的方法時，編譯器會返回它們未定義的方法。

有三種主要類型：

1. 數獨類，它實現了可迭代接口。它包含一個二維數組，就是難題。構造函數從掃描儀輸入中獲取文件並構建難題。它有一個迭代器方法來滿足接口要求。此方法返回類型爲SudokuIterator的interator。

2. SudokuIterator類，它實現了Iterator接口。這是Sudoku類的私人內部類。它也有一個2維數組和一個光標作爲屬性。它有標準的hasNext（），next（）和一個remove（）存根來滿足接口。我還添加了一個nextColumn（）和nextBox（），它根據光標位置返回一個數組。下一個方法已被覆蓋返回行。

3. 最後是Validator。這種方法是主要的方法。它有一個方法isSolution（），它返回一個布爾值，取決於從SudokuIterator類中定義的方法返回的每個數組的分析。

這是我的問題出現的地方;當使用迭代器方法實例化並返回一個SudokuIterator並嘗試使用添加的nextColumn（）和nextBox（）方法時，編譯器會返回這些方法未定義爲Iterator。

任何意見或建議將不勝感激。提前致謝。

import java.util.*; 

/** 
* Sudoku class represents the matrix of cells in a Sudoku puzzle 
* @version 01/05/2012 
* @author Bob Wilson 
*/ 

public class Sudoku implements Iterable<Cell []> 
{ 
    private Cell [] [] puzzle; 

    /** 
    * Default constructor should not be called. Make it private. 
    */ 
    private Sudoku() {} 

    /** 
    * Puzzle constructor that uses a Scanner object to read a file. 
    * File contains 81 numbers that are the values of the 81 cells. 
    * @param file a Scanner object on a File object 
    */ 
    public Sudoku(Scanner file) 
    { 
    int size = file.nextInt(); 
    System.out.println("Size: " + size); 
    puzzle = new Cell[size][size]; 
    for (int i = 0; i < size; i++) 
     for (int j = 0; j < size; j++) 
     puzzle[i][j] = new Cell(file.nextInt()); 
    } 

    public int getLength(){ 
     return this.puzzle.length; 
    } 


    class SudokuIterator implements Iterator<Cell []> { 

     private Cell [][] puzzle; 
     private int cursor; 

     public SudokuIterator(Cell [][] puzzle){ 

      this.puzzle = puzzle; 
      cursor = 1; 

     } 


     public boolean hasNext(){ 
      if(cursor <= this.puzzle.length){ 
       return true; 
      } 
      return false; 
    } 
     public Cell[] next(){ 
      Cell[] row = puzzle[cursor-1]; 
      cursor++; 
      return row; 
     } 

     public Cell[] nextColumn(){ 
      Cell[] column = new Cell[puzzle.length]; 
      for(int i = 0; i < puzzle.length; i++){ 
       column[i] = puzzle[i][cursor-1]; 
      } 
      cursor++; 
      return column; 
     } 

     public Cell[] nextBox(){ 
      Cell[] box = new Cell[puzzle.length]; 
      int boxIndex = 0; 
      for(int i = ((cursor - 1)/((int)Math.sqrt(puzzle.length)))*(int)Math.sqrt(puzzle.length) ; i < ((cursor - 1)/((int)Math.sqrt(puzzle.length)))*(int)Math.sqrt(puzzle.length) + (int)Math.sqrt(puzzle.length); i++){ 
       for(int j = (((cursor - 1) + ((int)Math.sqrt(puzzle.length))) % ((int)Math.sqrt(puzzle.length))) * ((int)Math.sqrt(puzzle.length)); j < (((cursor - 1) + ((int)Math.sqrt(puzzle.length))) % ((int)Math.sqrt(puzzle.length))) * ((int)Math.sqrt(puzzle.length)) + ((int)Math.sqrt(puzzle.length)); j++){ 
        box[boxIndex] = puzzle[i][j]; 
       } 
      } 
      cursor++; 
      return box; 
     } 
     public void remove(){} 
    } 
    /** 
    * Generates and returns a String representation of the puzzle cells 
    * @return A String representing the contents of the puzzle array 
    */ 
    public String toString() 
    { 
    // display the puzzle 
    String value = "Puzzle is:\n"; 

    for (int i = 0; i < puzzle.length; i++) { 
     for (int j = 0; j < puzzle[i].length; j++) 
     value += puzzle[i][j].toString(); 
     value += "\n"; 
    } 
    return value; 
    } 

    /** 
    * Instantiates and returns a new SudokuIterator object 
    * @return A SudokuIterator object on the puzzle array 
    */ 

    public SudokuIterator iterator(){ 

    SudokuIterator iterator = new SudokuIterator(this.puzzle); 
    return iterator; 

    } 


    } 
    /* 201340 */ 

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

/** 
* This class instantiates a Sudoku object passing a Scanner on a 
* file to the Sudoku constructor. It prints the puzzle using the 
* Sudoku toString method. It determines if the digit matrix is a 
* valid solution for a Sudoku puzzle or not and prints the result. 
* 
* @version 01/05/2012 
* @author Bob Wilson 
* 
*/ 

public class SudokuValidator 
{ 
    private Sudoku puzzle; 

    /** 
    * @param args - not used 
    */ 
    public static void main(String [] args) 
    { 
    Scanner scan = new Scanner(System.in); 
    System.out.println("Please enter name of file containing puzzle to verify"); 
    SudokuValidator myValidator = new SudokuValidator(scan.nextLine()); 
    System.out.println(myValidator.isSolution()); 
    } 

    public SudokuValidator(String fileName) 
    { 
    Scanner file = null; 
    try 
    { 
     file = new Scanner(new File(fileName)); 
    } 
    catch (Exception e) 
    { 
     System.out.println("Bad file name"); 
     System.exit(0); 
    } 

    puzzle = new Sudoku(file); 
    System.out.println(puzzle); 
    } 

    public boolean isSolution(){ 


     boolean flag = true; 
     Iterator<Cell[]> game = puzzle.iterator(); 

     while(game.hasNext()){ 
      Cell[] row = game.next(); 
      Cell[] column = game.nextColumn(); 
      Cell[] box = game.nextBox(); 


      for(Cell i: row){ 
       for(Cell j: row){ 
        if(j.equals(i.getValue())){ 
         flag = false; 
         return flag; 
        } 
       } 
      } 
     } 
     return flag; 
    } 
} /* 201340 */ 

Answer 1

的問題是，所聲明的類型game參考變量的是Iterator，它沒有定義任何nextColumn()方法，所以編譯器無法找到它。您可以通過將聲明的類型更改爲Sudoku.SudokuIterator（因爲這是一個內部類）來解決此問題。

變化：

Iterator<Cell[]> game = puzzle.iterator(); 

到：

Sudoku.SudokuIterator game = puzzle.iterator();