字符串的第一个字母大写

我不知道应该怎么将字符串的第一个字母转换为大写：

rackingSystem.toLowerCase(); // has capitals in every word, so first convert all to lower case
StringBuilder rackingSystemSb = new StringBuilder();
rackingSystemSb.append(rackingSystem);
rackingSystemSb.setCharAt(0, Character.toUpperCase(rackingSystemSb.charAt(0))); 
rackingSystem = rackingSystemSb.toString();

这段代码好像没有用。

请大虾指点，谢谢。

StringBuilder rackingSystemSb = new StringBuilder( rackingSystem.toLowerCase());  
rackingSystemSb.setCharAt(0, Character.toUpperCase(rackingSystemSb.charAt(0))); 
rackingSystem = rackingSystemSb.toString();