public static boolean isAsciiNumeric(char ch) {
        return ch >= '0' && ch <= '9';
    }
<p>Checks whether the character is ASCII 7 bit numeric.</p>

<pre>
  CharUtils.isAsciiNumeric('a')  = false
  CharUtils.isAsciiNumeric('A')  = false
  CharUtils.isAsciiNumeric('3')  = true
  CharUtils.isAsciiNumeric('-')  = false
  CharUtils.isAsciiNumeric('\n') = false
  CharUtils.isAsciiNumeric('&copy;') = false
</pre>

@param ch  the character to check
@return true if between 48 and 57 inclusive
android/android_framework/base/src/main/java/lang3/CharUtils.java