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Java - check if string contains any numbers
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In this article, we would like to show you how to check if a string contains any numbers in Java.
In this example, we use a regular expression (regex) with Pattern.matcher() to check if the strings contain any numbers.
xxxxxxxxxx1
import java.util.regex.Matcher;2
import java.util.regex.Pattern;3
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public class Example {5
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public static void main(String[] args) {7
String text = "ab123cd";8
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String regex = ".*\\d.*"; // regex to check if string contains any numbers10
Pattern pattern = Pattern.compile(regex); // compiles the regex11
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// find match between given string and pattern13
Matcher matcherText = pattern.matcher(text);14
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// return true if the string matched the regex16
Boolean textMatches = matcherText.matches();17
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System.out.println(textMatches); // true19
}20
}Output:
xxxxxxxxxx1
trueIn this example, we create a function that loops through the string and checks if any character is a digit with Character.isDigit(char ch) method.
Practical example:
xxxxxxxxxx1
public class Example {2
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public static void main(String[] args) {4
String letters = "ABCD";5
String numbers = "1234";6
String mixed = "a12b";7
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System.out.println(containsNumbers(letters)); // false9
System.out.println(containsNumbers(numbers)); // true10
System.out.println(containsNumbers(mixed)); // true11
}12
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public static boolean containsNumbers(String string) {14
if (string == null || string.isEmpty()) {15
return false;16
}17
for (int i = 0; i < string.length(); ++i) {18
if (Character.isDigit(string.charAt(i))) {19
return true;20
}21
}22
return false;23
}24
}Output:
xxxxxxxxxx1
false2
true3
true