java——String、StringBuffer

String：

　　记录一个子串在整串中出现的次数：

package package_name;
public class exp {
    public static void main (String[] args) {
        String str = "abcssssasasasnddbiweabcabcahabcccccabqwertadabc";
        String key = "abc";
        int res = getCounts(str, key);
        System.out.println(res);
    }
    public static int getCounts(String str, String key) {
        int count = 0;
        int index = 0;
        if(!str.contains(key)) {
            return count;
        }
        while((index = str.indexOf(key) )!= -1) {
            str = str.substring(index + key.length());
            count++;
        }
        return count;
    }
}