Question

我想按列计算String [][]中的字母数，到目前为止，我的代码是：

  for(int j = 0 ; j<matrix[0].length ;j++){
      for(int i  = 0 ; i< matrix.length ;i++ )
        if (Character.isLetter(matrix[j][i].charAt(j)))
        countChar++;
      }
      System.out.println(countChar + "letters");
      return countChar;

但程序的输出计算字符串有多少元素例如，如果String是：

String [][] C = {
  {"abc",    "abcd" ,        "abcd"},
  {"oroeo",  "kakakak" ,     "alsksjk"},
  {"abcdef", "asdasdasdasd", "asdasdasdasd"}, 
};

结果是9，但应该是14（按列的字母数）任何帮助都非常值得感谢！

Answer 1

您可以将2D矩阵定义为行数组或列数组。我假设您已将其定义为行数组，现在想要获取某列中的值。

所以你的数据是这样的：

abc             abcd             abcd
oroeo           kakakak          alsksjk
abcdef          asdasdasdasd     asdasdasdasd

三行三列。

获取中间列（索引为1）中的值，您需要获取数组元素：

matrix[0][1]
matrix[1][1]
matrix[2][1]

我认为您正在尝试计算每列中所有值的总长度。那会是这样的：

    // assume that the matrix has at least one row and thas the same number of columns in each row
    // take the number of columns in the first row for reference
    int numberOfColumns = matrix[0].length;
    for(int col = 0; col < numberOfColumns; col++) {
        int count = 0;
        // iterate over all the rows
        for(String[] row : matrix) {
            // count the length of the element in position col of this row
            count += row[col].length();
        }
        System.out.printf("%s characters in column %s", count, col);
    }

Answer 2

int n = 0;
// iterate row by row
for (int i = 0; i < C.length; i++) {
    n += C[i][0].length();
    // get the string at index 0 (or 1 or 2.. whichever you want) of the array and append its length
    // if you expect the string to contain numbers, then
    // run a for-loop on the string and check if its a letter
}
System.out.println(n);

Answer 3

尝试下面的问题是你的for循环的no。迭代的范围仅限于矩阵的大小：

for(int i = 0 ; i<C[0].length ;i++) {
                String matrixElement = C[i][0];
                System.out.println(matrixElement);
                for(int k =0 ;k < matrixElement.length();k++)
                if (Character.isLetter(matrixElement.charAt(k)))
                    countChar++;
        }

Answer 4

请格式化你的代码并刷新循环：

  private static int countByColumn(String[][] matrix, int column) {
    if (column < 0)
      return 0; // Or throw exception

    int countChar = 0;

    for (String[] line : matrix) {
      //DONE: jagged array: it may appear that the line is too short 
      if (line.length <= column) 
        continue;

      String item = line[column];

      for (int i = 0; i < item.length; ++i)
        if (Character.isLetter(item.charAt(i))) 
          countChar += 1;
    }  

    return countChar;
  }

测试：

  // 14
  int test = countByColumn(C, 0);

如何计算String [] []中每列的字母数？

4 个答案: