String num = '123';
System.debug('num isNumericSpace: ' + num.isNumericSpace());
System.debug('num isNumeric: ' + num.isNumeric());
System.debug('num isAlpha: ' + num.isAlpha());
System.debug('num isAlphanumeric: ' + num.isAlphanumeric());
String sample = '124CTRUY';
System.debug('sample isNumericSpace: ' + sample.isNumericSpace());
System.debug('sample isNumeric: ' + sample.isNumeric());
System.debug('sample isAlpha: ' + sample.isAlpha());
System.debug('sample isAlphanumeric: ' + sample.isAlphanumeric());
String noNumbers = 'Numbers';
System.debug('noNumbers isNumericSpace: ' + noNumbers.isNumericSpace());
System.debug('noNumbers isNumeric: ' + noNumbers.isNumeric());
System.debug('noNumbers isAlpha: ' + noNumbers.isAlpha());
System.debug('noNumbers isAlphanumeric: ' + noNumbers.isAlphanumeric());
String noNumbersWithSpace = 'No Numbers with space';
System.debug('noNumbersWithSpace isNumericSpace: ' + noNumbersWithSpace.isNumericSpace());
System.debug('noNumbersWithSpace isNumeric: ' + noNumbersWithSpace.isNumeric());
System.debug('noNumbersWithSpace isAlpha: '+ noNumbersWithSpace.isAlpha());
System.debug('noNumbersWithSpace isAlphanumeric: ' + noNumbersWithSpace.isAlphanumeric());
String numbersWithSpace = '1245 1236 1231';
System.debug('numbersWithSpace isNumericSpace: ' + numbersWithSpace.isNumericSpace());
System.debug('numbersWithSpace isNumeric: ' + numbersWithSpace.isNumeric());
System.debug('numbersWithSpace isAlpha: '+ numbersWithSpace.isAlpha());
System.debug('numbersWithSpace isAlphanumeric: ' + numbersWithSpace.isAlphanumeric());