I am trying to reverse an int using java, for some reason when given 0001234 my program somehow reads this as 668 and returns 886

Question

public static int reverseInt(int x) {
        String t = Integer.toString(x);
        StringBuilder sb = new StringBuilder(t);       
        sb = sb.reverse();       
        String b = sb.toString();        
        x = Integer.valueOf(b);
        return x;
    }

is my code and

        int x = 1234000;
        int b = 24230100;
        int g = 001234;
        int s = reverseInt(x);
        int q = reverseInt(b);
        int y = reverseInt(g);
        System.out.println("this is y:" + y);

is my tester. g is my int value that needs to be reversed but it is being read as 668. any idea why? when adding print statement for testing:

        String t = Integer.toString(x);
        System.out.println(x);
        StringBuilder sb = new StringBuilder(t);       
        sb = sb.reverse();       
        String b = sb.toString();   
        System.out.println(b);     
        x = Integer.valueOf(b);
        return x;
    }

my inital print for g is 668 and the print on line 7 returns 866