Complete Program

Here is the complete program. The differences in the code for each of the three numbers are highlighted in color. Noticing similarites like this often leads to better programs.

import java.util.Scanner;

class ComboLock
{
  public static void main ( String[] args )
  {
    int lockFirst = 6, 
        lockSecond = 12, 
        lockThird = 30;  // The combination
    int numb;            // a user-entered number
    Scanner scan = new Scanner( System.in );

    boolean correct = true;

    //First Number
    System.out.print("Enter first number: ");
    numb  = scan.nextInt();

    if ( numb != lockFirst )    
      correct = false ;

    //Second Number
    System.out.print("Enter second number: ");
    numb  = scan.nextInt();

    if ( numb != lockSecond )    
      correct = false  ;

    //Third Number
    System.out.print("Enter third number: ");
    numb  = scan.nextInt();

    if ( numb != lockThird )    
      correct = false  ;

    //Result
    if ( correct )
      System.out.println("Lock opens");
    else
      System.out.println("Lock does not open");
  }
}