Question

我是java的新手，我正在努力奋斗！我已经编写了以下代码但仍然遇到错误。我现在要做的就是用字母A填充一个5x5矩阵。这是我到目前为止所做的，我不确定是否还需要发布错误？任何帮助将非常感激。

public class Encryption {   
    private String Unencoded, FiveLetterKeyword, EncryptedMessage;

    //constructor method
    public Encryption(String U, String F, String E)
    {
        Unencoded = U;
        FiveLetterKeyword = F;
        EncryptedMessage = E;

    }
    //create 2D string array 5 by 5
    String Encrypt [][] = new String[5][5];        

    //create string filled with all letters of the alphabet
    String String = new String
        ("A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z");



    //method for loop to print out the matrix
    public static void matrix()
    //for loop to create matrix rows and columns        
    {
        for (int row = 1; row < Encrypt.length; row++)
        {
            for (int column = 1; column < Encrypt[row].length; column++)

            System.out.print(Encrypt[row][column] + " ");
        }       
    }

    //filling the array with the letter A
    public char Encrypt(char Encrypt[][])
    {
        //char[] alpha = alphabets.toCharArray;

        //declaring variable to fill array with A           
        char aChar = "A";

        for (int row = 1; row < Encrypt.length; row++)
        {
            for (int column = 1; column < Encrypt.length; column++)

            return Encrypt;
        }   
    }   
}

Answer 1

Java中的数组从零开始，这意味着它们从索引0开始，并且范围直到索引array.length-1。

您的代码在row处启动column和1 - 这意味着您正在跳过行/列0的初始化。这可能至少在哪里一些问题来自于，因为您使用5x5阵列（行/列0,1,2,3,4）作为4x4阵列（行/列1,2,3,4）。 / p>

还有一个事实是你的Encrypt方法实际上没有对数组进行任何赋值。你可能想要像这样初始化它：

// NOTE: changed return type to void -- this is a side-effect-only method!
public void Encrypt(char Encrypt[][])
{
    // NOTE: use single-quotes for chars. double-quotes are for strings.
    char aChar = 'A';
    // NOTE: changed the starting loop values from `1` to `0`
    for (int row = 0; row < Encrypt.length; row++)
    {
        // NOTE: technically Encrypt.length works here since it's a square
        // 2D array, but you should really loop until Encrypt[row].length
        for (int column = 0; column < Encrypt[row].length; column++)
        {
            // NOTE: set each entry to the desired char value
            Encrypt[row][column] = aChar;
        }
    }   
}

您的原始代码存在多个问题。查看注释中的NOTE条目，了解各个解释。

Answer 2

你错过了你想要完成的最重要的部分。

您在哪里将矩阵设置为字母A？

将您的加密功能更改为以下内容：

//filling the array with the letter A
public void Encrypt(char arr[][])
{
    //char[] alpha = alphabets.toCharArray;

    //declaring variable to fill array with A           
    char aChar = 'A';

    for (int row = 0; row < arr.length; row++)
    {
        for (int column = 0; column < arr[row].length; column++)
        {
            arr[row][column] = aChar;
        }
    }   
}

用Java填充2D数组

2 个答案: