求教一个正则表达式的问题

[serapme]

",1,s,f,d,f,s,f".replaceAll("(,[fs1]),[ds],f","$1")


为什么得到结果是,1,d,f
百思不得其解，求指点迷津

[XuanrenLu]

",1,s,f,d,f,s,f".replaceAll("(,[fs1]),[ds],f","$1") pattern = "(,[fs1]),[ds],f" $1 = (,[fs1]) ,1,s,f,d,f,s,f -- > [,1,s,f],d[,f,s,f] match twice ,1,s,f match pattern, replaced to ,1 ,f,s,f match pattern, replaced to ,f so, result is ",1,d,f"