统计一个字符串中"java"出现的次数

public class CountJava{

    public static void main(String[] args){

        String str = "dnajjavaNISLjavaERBjavafvsbdjavaFALjavaEUIcjavazs";
        int count = 0;
        int index = 0;

        while(str.indexOf("java") != -1){
            index = str.indexOf("java");
            str = str.substring(index + 4);
            count++;
        }

        System.out.println("字符串java出现次数为" + count);
    }

}