How to check if a character in a string is a digit or letter

Question

I have the user entering a single character into the program and it is stored as a string  I would like to know how I could check to see if the character that was entered is a letter or a digit  I have an if statement  so if its a letter its prints that it s a letter  and the same for a digit  The code I have so far doesn t work but I feel like I m close  Any help you can offer is appreciated      System out println  Please enter a single character        String character   in next       System out println character      if  character isLetter         System out println  The character entered is a letter           else  character isDigit         Syste out println  The character entered is a digit

User · Answer

You could use the existing methods from the Character class. Take a look at the docs:

http://download.java.net/jdk7/archive/b123/docs/api/java/lang/Character.html#isDigit(char)

So, you could do something like this...

String character = in.next();
char c = character.charAt(0);
...
if (Character.isDigit(c)) { 
    ... 
} else if (Character.isLetter(c)) {
    ...
}
...

If you ever want to know exactly how this is implemented, you could always look at the Java source code.

User · Answer

char temp   yourString charAt 0        if Character isDigit temp                                    else if  Character isLetter temp                                  else

User · Answer

Ummm  you guys are forgetting the Character isLetterOrDigit method   boolean x  String character   in next    char c   character charAt 0   if Character isLetterOrDigit charAt c         x   true

User · Answer

char charInt character charAt 0      if charInt gt  48  amp  amp  charInt lt  57       System out println  not character      else     System out println  Character      Look for ASCII table to see how the int value are hardcoded

User · Answer

This is a little tricky  the value you enter at keyboard  is a String value  so you have to pitch the first character with method line chartAt 0  where  0 is the index of the first character  and store this value in a char variable as in char c  line charAt 0  now with the use of method isDigit   and isLetter   from class Character you can differentiate between a Digit and Letter   here is a code for your program   import java util Scanner   class Practice    public static void main String   args         Scanner in   new Scanner System in      System out println  Input a letter        String line   in nextLine       char c   line charAt 0      if  Character isDigit c      System out println c    Is a digit       else if  Character isLetter c      System out println c    Is a Letter

User · Answer

You could use       if  Character isLetter character charAt 0

User · Answer

You could do this by Regular Expression as follows you could use this code  EditText et    EditText  findViewById R id editText   String NumberPattern     0-9     String Number   et getText   toString     if  Number matches NumberPattern   amp  amp  s length    gt  0           code for number   else         code for incorrect number pattern

User · Answer

This is the way how to check whether a given  character is alphabet or not  public static void main String   args         Scanner sc   new Scanner System in       char c   sc next   charAt 0        if  c  gt    a   amp  amp  c  lt    z       c  gt    A   amp  amp  c  lt    Z             System out println c     is an alphabet         else         System out println c     is not an alphabet

User · Answer

import java util     public class String char         public static void main String arg                 Scanner in   new Scanner System in           System out println  Enter the value            String data          data   in next             int len   data length            for  int i   0   i  lt  len   i                 char ch   data charAt i                if   ch  gt    0   amp  amp  ch  lt    9                     System out println  Number                               else if  ch  gt    a   amp  amp  ch  lt    z       ch  gt    A   amp  amp  ch  lt    Z                 System out println  Character                              else                  System out println  Symbol

User · Answer

By using regular expressions   boolean isChar   character matches   a-zA-z  1     boolean isDigit   character matches    d 1

User · Answer

You need to convert your string into character     String character   in next    char myChar   character charAt 0    if  Character isDigit myChar           print true     Check Character for other methods

User · Answer

I have coded a sample program that checks if a string contains a number in it  I guess it will serve for this purpose as well   public class test       public static void main String   args            String c          boolean b           System out println  Enter the value            Scanner s   new Scanner System in           c   s next            b   containsNumber c           try               if  b    true                    throw new CharacterFormatException                  else                   System out println  Valid String  t    c                           catch  CharacterFormatException ex                System out println  Exception Raised-Contains Number                          static boolean containsNumber String c            char   ch   new char 10           ch   c toCharArray             for  int i   0  i  lt  ch length  i                  if   ch i   gt   48   amp  amp   ch i   lt   57                     return true                                  return false            CharacterFormatException is a user defined Exception  Suggest me if any changes can be made

[java] How to check if a character in a string is a digit or letter

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