设int n ，打印1+3+5+...+n，当n为奇数，则累加到n，若为偶数，则累加到n-1，变量n的初始值在程序中指定
Scanner sc = new Scanner(System.in);
int num = sc.nextInt();
int cot = 0;
if(num%2==0) {
for(int i=1;i<=num-1;i=i+2) { //i每次循环加2，直到i等于num-1，停止
cot = cot + i;
}
System.out.println("n为偶数，从1加到n-1之和为:" + cot);
}else {
for(int i=1;i<=num;i=i+2) {
cot = cot +i;
}
System.out.println("n为奇数，从1加到n-1之和为:" + cot);
}
上面n为偶数时，条件应该为i<=n-1；等于号忘写了
public class Test_if_else {
public static void main(String[] args) {
// TODO Auto-generated method stub
//打印1+3+5+...+n，当n为奇数，则累加到n，若为偶数，则累加到n-1，变量n的初始值在程序中指定
Scanner sc = new Scanner(System.in);
System.out.println("请输入数字：");
int n = sc.nextInt();
int sum=0;
if(n%2==0) {
for(int i=1;i<n-1;) {
sum+=i;
i+=2;
}
System.out.print(sum);
}else {
for(int i=1;i<=n;) {
sum+=i;
i+=2;
}
System.out.println(sum);
}
}
}
package com.imooc;
public class helloword {
public static void main (String[] args) {
int sum = 0;
for (int i = 1;i<=100;i++)
{
if ( i%2 ==0 ) {
continue;
}
sum = sum + i;
}
System.out.println("100以内基数和为"+sum);
}
}