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Check the Character/First Character Of a String is Number or Not in Java

Core Java » on Oct 14, 2012 { 5 Comments } By Sivateja

Let us see how to find whether the given Character of a String is a number or first Character of any String is a number or not ?

CharNumber.java

package java4s;

public class CharNumber {

      public static void main(String... args)
      {
          String str = "java4s";

          //Check whether the given character is a number of not ?

          for(int i=0; i<str.length();i++)
          {

              Boolean flag = Character.isDigit(str.charAt(i));

              if(flag){
                 System.out.println("'"+str.charAt(i)+"' is a number");
              }
              else{
                 System.out.println("'"+str.charAt(i)+"' is not a number");
              }

          }

          //----------------------------------------------------------------
          //To check first character is a number or not ?

              Boolean flag2 = str.substring(0, 1).matches("[0-9]");

              if(flag2){
                 System.out.println("First Character is a number..!");
              }
              else{
                 System.out.println("First character is not a number..!");
              }

      }
}

Output

‘j’ is not a number
‘a’ is not a number
‘v’ is not a number
‘a’ is not a number
‘4’ is a number
‘s’ is not a number
First character is not a number..!

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Comments

5 Responses to “Check the Character/First Character Of a String is Number or Not in Java”
  1. There is a lot of very useful knowledge in your post to help me solve problems.I enjoy reading your post and hope to see more.

  2. venkatesh says:

    when to use equals() method and compareTo() method can u explain.

  3. suseela says:

    i couldn’t found multi thread concept in (core java) java4s

  4. vidya says:

    what is difference between string,string buffer,string builder concepts

  5. Jamal Mirza says:

    There is lot of materials regarding Java as well as many technology i started to learn and practice from Java4s it is awesome blog.

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