java中怎麽確定壹個字符串在另壹個字符串中出現的次數

String str2 = "ok ";

int total = 0;

for (String tmp = str1; tmp != null&&tmp.length()> =str2.length();){

if(tmp.indexOf(str2) == 0){

total ++;

}

tmp = tmp.substring(1);

}

System.out.println(str1+ "中含有 "+total+ "個 "+str2);