CODEWITHSUNDEEP
javastringif-statementcompare
coffeemonitor
coffeemonitor

Reputation: 13120

Java - If statement not working (comparing strings)

When I grab the IP Address from my open socket, as someone has sent me a stream, I noticed that the IP has a forward-slash.

I just plan to simply omit it. But first I want to validate the first character in the string is the forward-slash:

String dataSource = data.getAddress().toString();

if(dataSource.substring(0,1) == "/"){
    System.out.println("trailing forward slash, delete it ");  
    dataSource = dataSource.substring(1);
}

This IF statement isn't being detected.

Anyone see what I'm doing wrong?

Upvotes: 4

Views: 3898

Answers (11)

Sean F
Sean F

Reputation: 2390

you should use .equals for string comparrisons so 

if(dataSource.substring(0,1) == "/")

should be

if ("/".equals(dataSource.substring(0,1)))

Upvotes: 1

user207421
user207421

Reputation: 310859

Why use a String? You're just creating this problem for yourself. Use the datatype provided:

InetAddress dataSource = data.getInetAddress();

or

SocketAddress dataSource = data.getRemoteSocketAddress();

Then you have a semantically-aware .equals() method in both cases.

Upvotes: 0

QuokMoon
QuokMoon

Reputation: 4425

String dataSource = "/hell";

        if(dataSource.substring(0,1).equalsIgnoreCase("/")){
            System.out.println("trailing forward slash, delete it ");  
            dataSource = dataSource.substring(1);
        }

run this program. this is working..

Upvotes: 0

Amit Deshpande
Amit Deshpande

Reputation: 19185

Always use equals when comparing values. Having said that you can just use indexOf method for your purpose 

   if (dataSource.indexOf('/') == 0) {
        dataSource = dataSource.substring(1);
    }

Upvotes: 0

Srinivas B
Srinivas B

Reputation: 1852

If you want to test only, the first character , you can try the method,

dataSource.charAt(0)=='/'

Upvotes: 2

Asish AP
Asish AP

Reputation: 4441

Try this

if (("some string to check").equals(myString)){ doSomething(); }

Upvotes: 0

darcyy
darcyy

Reputation: 5276

You need to do dataSource.substring(0,1).equals("/"), which actually checks the content of the strings. == only checks whether both sides are the same object.

Upvotes: 0

Nidhish Krishnan
Nidhish Krishnan

Reputation: 20741

please use .equals

if("/".equals(dataSource.substring(0,1))){
    System.out.println("trailing forward slash, delete it ");  
    dataSource = dataSource.substring(1);
}

instead of ==

Upvotes: 2

Timr
Timr

Reputation: 1032

Use .equals(Object) or .equalsIgnoreCase(String) for comparing Strings.

Upvotes: 0

Abubakkar
Abubakkar

Reputation: 15644

For string comparisons use equals method, as it is more reliable than using == operator (it compares the content while == comnpares the references ) :

Try using equals method :

if(dataSource.substring(0,1).equals("/")){

Upvotes: 2

Michael
Michael

Reputation: 3332

You're comparing strings with ==, which means you're checking to see if these two strings are literally the same string reference.

Use equal() to check and see if two strings contain the same characters.

See: http://www.leepoint.net/notes-java/data/expressions/22compareobjects.html

Upvotes: 0

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