java：构建Tool类，实现三个功能 1.输出16以内所有自然数的和2.输出所有水仙花数3.输出33以内所有3的倍数

public class Tool {

public static void main(String[] args) {
System.out.println("1. 16以内所有自然数的和为：" + sumOfNaturalNumbers(16));
System.out.println("2. 1000以内所有水仙花数为：");
printAllNarcissisticNumbers(1000);
System.out.println("3. 33以内所有3的倍数为：");
printAllMultiplesOfThree(33);
}

// 1. 输出16以内所有自然数的和
public static int sumOfNaturalNumbers(int n) {
int sum = 0;
for (int i = 1; i <= n; i++) {
sum += i;
}
return sum;
}

// 2. 输出所有水仙花数
public static void printAllNarcissisticNumbers(int n) {
for (int i = 1; i <= n; i++) {
int sum = 0;
int num = i;
int len = String.valueOf(i).length();
while (num > 0) {
int digit = num % 10;
sum += Math.pow(digit, len);
num /= 10;
}
if (sum == i) {
System.out.print(i + " ");
}
}
System.out.println();
}

// 3. 输出33以内所有3的倍数
public static void printAllMultiplesOfThree(int n) {
for (int i = 1; i <= n; i++) {
if (i % 3 == 0) {
System.out.print(i + " ");
}
}
System.out.println();
}
}