In this post, we will learn Java program to check if String contains digits.
Here I will discuss two methods to find the numeric in a string.
- Using regular expression
- Using isDigit() method
Table of Contents
Java Program To Check if String Contains Digits
Method 1: Using Regular Expression
package demopkg;
public class CheckNumericValue {
public static void main(String[] args) {
String sInput = "Page Not Found - 404";
// using regular expression
System.out.println(sInput.replaceAll("[^0-9]",""));
}
}
Output: 404
Explanation: Here we have used replaceAll() method to replace string value with null.
[^0-9] – Represent non-numeric value. [0-9] – Represent numeric value
Method 2: Using isDigit() method
package demopkg;
public class CheckIsNumeric {
public static void main(String[] args) {
String sInput = "Page Not Found - 404";
char[] c = sInput.toCharArray();
StringBuffer sb =new StringBuffer();
boolean flag =false;
for (char ch: c) {
if(Character.isDigit(ch)) {
sb.append(ch);
flag = true;
}
}
if(flag) {
System.out.println(sb);
}else {
System.out.println("Not contains digits");
}
}
}
Output: 404
Explanation: isDigit() is the method of Character class. First I have converted string into array of character then using for-each loop iterate each character then in if condition I checked numeric value one by one using isDigits() method.
Java checks if string contains letters and numbers
In above program we have already used regular expression [^0-9] to find the letters in a given string, same like using [a-zA-Z] can be used to find letters in a given string.
package demopkg;
public class CheckNumericValue {
public static void main(String[] args) {
String sInput = "Internal Server Error - 404";
// using regular expression
System.out.println(sInput.replaceAll("[^a-zA-Z]"," "));
System.out.println(sInput.replaceAll("[a-zA-Z]"," "));
}
}
Output:
Internal Server Error
– – 404
How To Check if a string contains only digits Python
If a string only numbers if the string’s character consist 0 to 9 numeric value. For example – “04567” etc.
# Initialising string
ini_str1 = '1234556'
ini_str2 = 'ghk123bc'
# printing initial string
print ("Initial Strings : ", ini_str1, ini_str2)
# Using isdigit()
if ini_str1.isdigit():
print ("String1 contains all numbers")
else:
print ("String1 doesn't contains all numbers")
if ini_str2.isdigit():
print ("String2 conatins all numbers")
else:
print ("String2 doesn't contains all numbers")
Output:
Initial Strings : 1234556 ghk123bc
String1 contains all numbers
String2 doesn’t contains all numbers
Summary:
In this post we have learnt ‘Java program to check if String contains digits‘ using different ways.
Thanks for reading! Happy Learning 🙂
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