将字符串分割成字符串数组
str.split("以这个字符串为分割");
String[] s="aabbcc".split("bb");
System.out.println(Arrays.toString(s));
输出aacc


str.replace("要替换的字符串","替换成这个字符串");
"aabbcc".replace("bb","dd");
输出aaddcc