面试题：

1.计算字符串"23743298"奇数位的和、偶数位的和

public class demo1 {

	public static void main(String[] args) {
		String s = "23743298";
		int s1 = 0;
		int s2 = 0;
		for(int i=0; i < s.length(); i++) {
			if(i%2 == 0) {
				s1 += Integer.parseInt(s.substring(i, i+1));
			}else {
				s2 += Integer.parseInt(s.substring(i, i+1));
			}
		}
		System.out.println(s+"奇数位的和是:"+s1);
		System.out.println(s+"偶数位的和是:"+s2);
	}
}

2.用代码统计"helloworld"中字母"o"的个数

public class demo2 {

	public static void main(String[] args) {
		String s = "helloworld";
		//字符串转字符
		char[] s1 = s.toCharArray();
		int s2 = 0;
		for(int i=0; i < s1.length; i++) {
			if(s1[i] == 'o') {
				s2 += 1;
			}
		}
		System.out.println(s+"中字母'o'的个数是:"+s2);
	}
}