Java简单代码把杨辉三角写入文档中在从文档中打印出来

以下是Java代码实现：

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class YangHuiTriangle {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入杨辉三角的行数：");
        int n = scanner.nextInt();
        scanner.close();

        int[][] triangle = new int[n][n];
        for (int i = 0; i < n; i++) {
            triangle[i][0] = 1;
            triangle[i][i] = 1;
            for (int j = 1; j < i; j++) {
                triangle[i][j] = triangle[i-1][j-1] + triangle[i-1][j];
            }
        }

        File file = new File("yanghui.txt");
        try {
            FileWriter writer = new FileWriter(file);
            for (int i = 0; i < n; i++) {
                for (int j = 0; j <= i; j++) {
                    writer.write(triangle[i][j] + " ");
                }
                writer.write("\n");
            }
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            Scanner fileScanner = new Scanner(file);
            while (fileScanner.hasNextLine()) {
                System.out.println(fileScanner.nextLine());
            }
            fileScanner.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

该程序先从控制台读取杨辉三角的行数，然后使用二维数组存储杨辉三角，并将其写入文本文件中。最后，程序使用Scanner从文本文件中读取杨辉三角并打印到控制台。