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javastringinteger

Why does Integer.parseInt() remove 0 from string values?

I have been trying to investigate why Integer.parseInt() removes 0 and returns the remaining numbers. For example:

@Test
public void testInteger() {
    System.out.println(Integer.parseInt("01234"));
    System.out.println(Integer.parseInt("12340"));
}

The first line prints 1234 and the second 12340. Why is the 0 removed from the first line. This does not make sense. I am aware a Integer is the wrapper object of an int and an int stores 32 bits.

Could you please explain why?

Solution

  • Because you are using the string "01234" as an integer (with parseInt()), the system.out.println is printing an integer.

    "01234" as an integer would be 1234. This is because 0 is the only integer that starts with a zero.

    None of these are real numbers:

    0456,
0234, 
05555555, 
01

    If you were to store "01234" as a string, the 0 would hold its value.