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java - 如何检查字符串是否只包含字母？

问题描述

如何检查字符串是否只包含字母？是否有任何特定功能可以做到这一点？

标签： java

解决方案

I don't know about a direct function But you can follow these steps :

1) Take a string as input 2) By using toLower() method, convert everything into lower case 3) Use toCharArray() method of the String class to convert into a character array 4) Now check whether at every location has character between a to z

code : 

import java.util.Scanner;
public class StringValidation{
   public boolean validtaeString(String str) {
      str = str.toLowerCase();
      char[] charArray = str.toCharArray();
      for (int i = 0; i < charArray.length; i++) {
         char ch = charArray[i];
         if (!(ch >= 'a' && ch <= 'z')) {
            return false;
         }
      }
      return true;
   }
   public static void main(String args[]) {
      Scanner sc= new Scanner(System.in);
      System.out.println("Enter a string value: ");
      String str = sc.next();
      StringValidation obj = new StringValidation();
      boolean bool = obj.validtaeString(str);
      if(!bool) {
         System.out.println("Given String is invalid");
      }else{
         System.out.println("Given String is valid");
      }
   }
}

Here is the output: 

Output: 

Enter a string value:
24stackoverflow
Given String is invalid
------------------------
Enter a string value:
StackOverflow
Given String is valid

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