java - The operator < is undefined for the argument type(s) String, int -

i'm having problem when trying run program. program supposed receive number , compare int. understand program thinks i'm trying compare string int , not happy it. can do?

import java.util.scanner; public class c {     public static void main(string args[]) {         scanner input = new scanner (system.in);         string age = input.nextline();         if (age < 50){             system.out.println("you young");         }else{             system.out.println("you old");         }     } } 

you cannot compare string int using numerical comparison-operator. §15.20.1 of java language specification describes seeing:

the type of each of operands of numerical comparison operator must type convertible (§5.1.8) primitive numeric type, or compile-time error occurs.

since string not convertible primitive numeric-type, cannot compare against integer. therefore have 2 options:

• you can convert string int using integer#parseint:

  int age = integer.parseint(agestring); 

• but in case, since reading in input, better bypass whole parseint bit , read in int directly:

  int age = input.nextint(); 

keep in mind though still have deal possibility of invalid input.