Capitalise first letter in String [duplicate]

问题

This question already has answers here:

How to capitalize the first letter of a String in Java? (51 answers)

Closed 6 years ago.

I'm having trouble converting the first letter to Capital in a String:

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();

This doesn't seem to work..

Any suggestions?

回答1:

Try doing:

rackingSystem = rackingSystem.toLowerCase();

Instead of:

rackingSystem.toLowerCase(); 

Strings are immutable, you must reassign the result of toLowerCase().

Easier though, (as long as your String is larger than length 2):

rackingSystem = rackingSystem.substring(0,1).toUpperCase() + rackingSystem.substring(1).toLowerCase();

回答2:

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

来源：https://stackoverflow.com/questions/15259774/capitalise-first-letter-in-string