【Java】【LeetCode】字符串操作

将空格替换成"%20"

String a=s.replace(" ","%20");//注意replace不是直接在s上做修改，而是返回了一个字符串

StringBuilder

  StringBuilder sb=new StringBuilder("1234ac");
  sb.append("123");//1234ac123
  sb.insert(6,"-");//1234ac-123
  int index=sb.indexOf(ac);//index=4
  sb.insert(index,kkk);//1234kkkac-123