java输出1-100之间的数并求和for+while+do while实现

public static void main(String args[]) {
//do while
        int sum = 0; //当前之和
        int i = 1; //加数
        do {
        if (i%2==0){
        sum+=i;
        }
        i++;
        }while (i<=100);
        System.out.println(sum);
    }
}

public static void main(String args[]) {
//while
             int res=0;
             int a=1;
             while(a<101) {
                 if(a%2==0) {
                     res+=a;     
                 }
                 a++;
             }
             System.out.println(res);
}
}

    public static void main(String []args){
// for
        int sum=0;
        for(int i=1;i<101;i++){
            if(i%2==0){
            sum+=i;
            }
        }
        System.out.println(sum);
        }
}