JSP错误提示Syntax error on token ""\',\'"", delete this token

An error occurred at line: 78 in the jsp file: index.jsp
Syntax error on token ""\',\'"", delete this token

75: Class.forName(dri);
76: con =DriverManager.getConnection(conStr,"test_db","test_pw");
77: stmt = con.createStatement();
78: String sql="insert into table1(userid,username,nickname) values ('" + userid + "','" + username + "','" + nickname + "');";
79: stmt.execute(sql);

语法错误令牌""\',\'""，删除此令牌....

但是我代码里都没有\号，这是哪来的？
难道说，这里的"','"里的单引号'要用转义字符\'才对吗？

当然要转义了，不然与insert前面的引号构成一个块，就断掉了，是语法错误
可将String sql='';用单引号就不用转义