public class Ba{
  public static void main(String args[]){
   int x = 1;
   int sum = o;
  while(x<=100){
   sum = sum + x;
   x+=2;
   }
  System.out.println("sum="+sum);
 }
}  

sum=0不是sum=o

public class Tset6 {

    public static void main(String args[]){
        int sum=0;
        for (int i = 0; i <=100; i++) {
                if(i%2==1){
                    sum+=i;
                }
        }
        System.out.println("sum="+sum);
    }
}