如何打印二维数组中的第一个字符

Question

我试图打印每个单词的第一个字符放入一个二维数组。我得到一个错误，当我试图打印它的子串。

String [][] manyWords = { 
        {"red", "bling", "grand"},
        {"bridge", "queen", "chair"}
    };
    System.out.print(manyWords.substring(0, 1));

我得到一个不可编译的源代码错误。

Answer 1

以下是流版本：

Stream.of(manyWords).flatMap(Stream::of).map(s -> s.substring(0, 1))
    .forEach(System.out::print);

Answer 2

以下代码应该可以实现您的目标：

    public class test{

      public static void main(String[] args){

    // Declare test array
    String [][] manyWords = { 
            {"red", "bling", "grand"},
            {"bridge", "queen", "chair"}
        };

    // Since it is a 2d array, loop through it with both an x and y coordinate
    // Check https://stackoverflow.com/questions/25798958/iterate-through-2-dimensional-array for more info
    for (int i = 0; i < manyWords.length; i++){
      for (int j = 0; j < manyWords[i].length; j++){

        // Set the current character using charAt
        char curr = manyWords[i][j].charAt(0);

        // Print it out
        System.out.println(curr);

      } //end inner for
    } //end outer for
  } //end psvm
} //end class

印刷品：

r
b
g
b
q
c

Answer 3

您必须使用一些循环（我更喜欢每个循环而不是for/while）：

for(String[] strArr : manyWords){
   for(String str : strArr){
       System.out.println(str.substring(0,1);}}