First char to upper case

Question

Possible Duplicate    How to upper case every first letter of word in a string    Most efficient way to make the first character of a String lower case        I want to convert the first letter of a string to upper case  I am attempting to use replaceFirst   as described in JavaDocs  but I have no idea what is meant by regular expression   Here is the code I have tried so far   public static String cap1stChar String userIdea        String betterIdea  userIdeaUC      char char1      userIdeaUC   userIdea toUpperCase        char1   userIdeaUC charAt 0       betterIdea   userIdea replaceFirst char1        return betterIdea     end cap1stChar   The compiler error is that the argument lists differ in lengths  I presume that is because the regex is missing  however I don t know what that is exactly

User · Answer

Comilation error is due arguments are not properly provided, replaceFirst accepts regx as initial arg. [a-z]{1} will match string of simple alpha characters of length 1.

Try this.

betterIdea = userIdea.replaceFirst("[a-z]{1}", userIdea.substring(0,1).toUpperCase())

User · Answer

Regular Expressions  abbreviated  regex  or  reg-ex   is a string that defines a search pattern   What replaceFirst   does is it uses the regular expression provided in the parameters and replaces the first result from the search with whatever you pass in as the other parameter   What you want to do is convert the string to an array using the String class  charAt   method  and then use Character toUpperCase   to change the character to upper case  obviously   Your code would look like this   char first   Character toUpperCase userIdea charAt 0    betterIdea   first   userIdea substring 1     Or  if you feel comfortable with more complex  one-lined java code   betterIdea   Character toUpperCase userIdea charAt 0     userIdea substring 1     Both of these do the same thing  which is converting the first character of userIdea to an upper case character

User · Answer

public static String cap1stChar String userIdea        char   stringArray   userIdea toCharArray        stringArray 0    Character toUpperCase stringArray 0        return userIdea   new String stringArray

User · Answer

userIdeaUC   userIdea substring 0  1  toUpperCase     userIdea length    gt  1   userIdea substring 1          or  userIdeaUC   userIdea substring 0  1  toUpperCase    if userIdea length    gt  1     userIdeaUC    userIdea substring 1

User · Answer

For completeness  if you wanted to use replaceFirst  try this   public static String cap1stChar String userIdea      String betterIdea   userIdea    if  userIdea length     0          String first   userIdea substring 0 1       betterIdea   userIdea replaceFirst first  first toUpperCase           return betterIdea     end cap1stChar

User · Answer

String toCamelCase String string        StringBuffer sb   new StringBuffer string       sb replace 0  1  string substring 0  1  toUpperCase         return sb toString

User · Answer

Or you can do  s   Character toUpperCase s charAt 0     s substring 1

[java] First char to upper case

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