怎么用java输出杨辉三角

下面是一个用Java输出杨辉三角的示例代码：

import java.util.*;  public class YangHuiTriangle {     public static void main(String[] args) {         Scanner sc = new Scanner(System.in);         System.out.println("请输入要输出的行数：");         int numRows = sc.nextInt();                  List<List<Integer>> triangle = generate(numRows);         for (List<Integer> row : triangle) {             for (int num : row) {                 System.out.print(num + " ");             }             System.out.println();         }     }          public static List<List<Integer>> generate(int numRows) {         List<List<Integer>> triangle = new ArrayList<>();                  if (numRows == 0) {             return triangle;         }                  List<Integer> firstRow = new ArrayList<>();         firstRow.add(1);         triangle.add(firstRow);                  for (int i = 1; i < numRows; i++) {             List<Integer> prevRow = triangle.get(i - 1);             List<Integer> currRow = new ArrayList<>();                          currRow.add(1);             for (int j = 1; j < i; j++) {                 currRow.add(prevRow.get(j - 1) + prevRow.get(j));             }             currRow.add(1);                          triangle.add(currRow);         }                  return triangle;     } } 

运行这段代码后，输入要输出的行数，程序将会输出相应行数的杨辉三角。