Java If Statement

Question

public class If {
public static void main(String[] args) {

var myVar = "Emma";
int myInt = 1;

    if (!(myVar == myInt)) {

        System.out.println("Access granted.");

    }

}
}

I am learning Java now. What I should do now is to print out 'true'.

First, I tried declaring the var and int. Then I put ! operator to change 'false' into 'true'.

I thought this would work, but it doesn't. Why doesn't it work? Shouldn't I declare anything when I use the if statement? Thank you

I guess myvar is a String. You have to use equals to compare — Jens
– Jens, Commented May 20, 2017 at 17:13

Darshan Mehta · Accepted Answer · 2017-05-20 18:12:02Z

2

the accepted answer is wrong

Contarary to what @dasblinkenlight's answer suggests, you can't compare the values of different type, even with equals. You first need to convert them into same type and then call equals, ofcourse it depends on how a class has overridden equals() method as well, e.g.:

String myVar = "1";
int myInt = 1;
System.out.println(myVar.equals(String.valueOf(myInt)));
System.out.println(myVar.equals(myInt));

This will print true and false with and without conversion.

edited May 20, 2017 at 18:12

answered May 20, 2017 at 17:17

Darshan Mehta

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Comments

Mahendra Gunawardena · Accepted Answer · 2017-05-20 19:58:58Z

1

You can't equal string to integer type. It's different types. Read OCA.
Make variable strong type. Not var but string.
Not (!(statement)) but (!statement)

edited May 20, 2017 at 19:58

Mahendra Gunawardena

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answered May 20, 2017 at 17:14

user8041441

Comments

Sergey Kalinichenko · Accepted Answer · 2017-05-20 18:01:45Z

-1

== cannot be used for comparison between an int and a String. However, you can use equals method:

if (!myVar.equals(myInt)) {
    ...
}

This is possible because of autoboxing.

Obviously, the comparison is going to fail regardless of the value of 'myVar' because the types are different. If you need to compare a string to an int reliably, first convert your string to int, and then compare with ==.

Of course, you need to declare myVar properly with String type.

edited May 20, 2017 at 18:01

answered May 20, 2017 at 17:12

Sergey Kalinichenko

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2 Comments

Darshan Mehta Over a year ago

equals with String and int will return false, even if the values are same. E.g. String var = "5";int var1 = 5;System.out.println(var.equals(var1));

Sergey Kalinichenko Over a year ago

@DarshanMehta of course, this will never return true. I assumed that's what OP wanted to achieve, though. Anyway, I added a brief explanation of what to do if he wanted to compare a string and an int.

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