web development helpdesk

Use static method Integer.parseInt() and catch the exception that is thrown when the number cannot be parsed.

String s = "123";
boolean isValidInteger = false;
try
{
   int i = Integer.parseInt(s);

   // s is a valid integer

   isValidInteger = true;
}
catch (NumberFormatException ex)
{
   // s is not an integer
}

written by objects \\ tags: int, string, validation

String s = "321";
boolean isNumber = s.matches("-?\\d+");

written by objects \\ tags: int, regexp, string

You can either use the static toString() method in the Integer class, or string concatenation can also be used. We’d recommend using the toString() method.

int i = 123;
String s = Integer.toString(i);

// An alternative would be to use
// the following string concatenation

String s2 = "" + i;

written by objects \\ tags: conversion, int, string