// Java中 获取指定字符串在另一个字符串中出现的次数
        //方法一、//不区分大小写
        String str = "Hello,my name is Ben.Please visit my website at http://www.forta.com/.";
        String regex = "My";
        Pattern pattern = Pattern.compile(regex,Pattern.CASE_INSENSITIVE);
        int count = 0;
        Matcher match = pattern.matcher(str);
        while (match.find()) {
            count++;
        }
        System.out.println(count);
        
        //方法一、//区分大小写
        String regex1 = "my";
        Pattern pattern1 = Pattern.compile(regex1,Pattern.CASE_INSENSITIVE);//不区分大小写
        int count1 = 0;
        Matcher match1 = pattern1.matcher(str);
        while (match1.find()) {
            count1++;
        }
        System.out.println(count1);

        //方法二、
        String reg = "my";
        int count2 = 0;
        int index1 = 0;
        //indexOf方法返回一个整数值，指出 String 对象内子字符串的开始位置。如果没有找到子字符串，则返回 -1
        while ((index1 = str.indexOf(reg, index1)) != -1) {
            index1 = index1 + reg.length();
            count2++;
        }
        System.out.println(count2);


2
2
2

        String input = "I like Java,jAva is very easy and jaVa is so popular.";  
        String replacement="ccc";  
        System.out.println(input);  
        System.out.println(input.replaceAll("java", replacement));  
        System.out.println(input.replaceAll("(?i)java", replacement)); 


I like Java,jAva is very easy and jaVa is so popular.
I like Java,jAva is very easy and jaVa is so popular.
I like ccc,ccc is very easy and ccc is so popular. 

ffunction myFunction(){
  //方法一、 通过分割获取长度原理
  var str = "Hello,my name is Ben.Please visit my website at http://www.forta.com/.";
  var regex = "my";
  var n = (str.split(regex)).length-1;
  alert(n); 
    
  //方法二、通过正则实现
  //eval(string) 函数可计算某个字符串，并执行其中的的 JavaScript 代码。
  var reg=eval("/My/ig");//g代表全局查找，i代表不区分字母大小写
  var count = str.match(reg).length;
  alert(count); 
}

都弹出 2