Comparing String with String Values

Question

Possible Duplicate:
Java String.equals versus ==

I have a string called DomainType which usually holds values like "edu,com,org..etc" from a url. I used an if else statement to help check the data type and output a JOptionPane. For some reason whenever you type any domain type, It gives you the last option.

Here is a Snippet from the code I wrote:

DomainType = URL.substring(URLlength - 3, URLlength);

if (DomainType == "gov") {
    JOptionPane.showMessageDialog(null, "This is a Government web address.");
}
else if (DomainType == "edu") {
    JOptionPane.showMessageDialog(null, "This is a University web address.");
}
else if (DomainType == "com") {
    JOptionPane.showMessageDialog(null, "This is a Business web address.");
}
else if (DomainType == "org") {
    JOptionPane.showMessageDialog(null, "This is a Organization web address");
}
else {
    JOptionPane.showMessageDialog(null, "This is an unknown web address type.");
}

so the DomainType gives me edu or com no problem but i think it's my if statement I'm not doing right.

I wonder how many millions of hours have been wasted due to the Java designers deciding to use == this way... We'll probably see the same questions pop up for ever... sigh — JRL, Oct 01 '11 at 14:24
Why should the "==" operator work differently for `String` than any other object? That would be stupid... even more stupid than the string concatenation operator looking the same as the arithmetic addition operator. — erickson, Oct 01 '11 at 14:52

darioo · Answer 1 · 2011-10-02T10:00:07.923

4

When comparing strings, never use ==, use equals. So, instead of

DomainType == "org"

use

DomainType.equals("org")

Why? == will compare references. That means: memory values. And they may not be equal for your strings. equals will compare values, and that is what you want.

edited Oct 02 '11 at 10:00

answered Oct 01 '11 at 14:19

darioo

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score 1 · Answer 2 · answered Oct 01 '11 at 14:19

1

To compare content use equals, not == (which compares references):

if (DomainType.equals("gov")) {

answered Oct 01 '11 at 14:19

MByD

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It's right,'==' is often used when compare object references. – Vacker Oct 01 '11 at 14:29

score 0 · Answer 3 · answered Oct 01 '11 at 17:15

0

On a side note, a mega-if is probably not the most elegant way to do that - http://www.antiifcampaign.com/ - sorry, just being pedantic.

The .equals() method is the right way to compare objects indeed.

answered Oct 01 '11 at 17:15

Savino Sguera

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Comparing String with String Values

3 Answers3