牛客代码提交出错，求大神给看看（附代码）

import java.util.Scanner;

public class Main {//字典排序
	public static void dictionary(int num) {//输入为字典排序的字符串个数
		if (num == 0) {
			System.out.println("");
		} else {
            Scanner scanner = new Scanner(System.in);
			String[] str = new String[num];
			for (int i = 0; i < num; i++) {//向字符串数组中输入字符串
				str[i] = scanner.nextLine();
			}
			for (int i = 0; i < num - 1; i++) {//排序
				String s = str[i];
				for (int j = i + 1; j < num; j++) {
					if (s.compareTo(str[j]) > 0) {
						str[i] = str[j];
						str[j] = s;
						s=str[i];
					}
				}
			}
			for (int i = 0; i < num; i++) {
				System.out.println(str[i]);
			}
		}
	}

	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		while (scanner.hasNext()) {
			int num = scanner.nextInt();
			dictionary(num);
		}
	}
}提交显示----->运行错误:请检查是否存在数组越界非法访问，野指针乱访问，空指针乱访问等情况
菜鸟初学Java实在是看不出哪有问题啊，eclipse上运行也没显示有问题，跪求大神指导下，谢谢