if () not working

Question

This is my code:

Log.d("inf", loader);
if (loader == "Klasse"){
    Log.d("inf", "Klasse yes");
    OPTS = new String[] { //Something };
} else {
    Log.d("inf", "Klasse no");
    OPTS = new String[] { //Something };
}

In the first Line, the Output is exactly "Klasse" but the next output is everytime "Klasse no". The loader String is set as follows:

String loader = "";
Bundle exta = getIntent().getExtras();
    if(exta !=null) {
        try {
            json = new JSONObject(exta.getString("json"));
            loader = exta.getString("order");
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

Do you guys have any Idea whats wrong?

possible duplicate of [Java string comparison?](http://stackoverflow.com/questions/995918/java-string-comparison) — Jon Skeet, May 13 '12 at 19:27
@blackbelt isn't that deprecated? (Just a question, i'm an 'enthusiast programmer', not a professional) — 11684, May 13 '12 at 19:28
there is almost 1 question everyday with the same thing. `==` instead of `equals()` — Kazekage Gaara, May 13 '12 at 19:32
@Styler2go You don't have to be sorry. I was just saying generally. :-) — Kazekage Gaara, May 13 '12 at 19:33
@11684 No, it is not. http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#compareTo%28java.lang.String%29 — Blackbelt, May 13 '12 at 19:33
@11684: That's because he didn't perform adequate diagnostic steps before posting, IMO. — Jon Skeet, May 13 '12 at 22:29

score 11 · Accepted Answer · answered May 13 '12 at 19:26

11

The == comparison operator compares references rather than values. You need to compare the values and so need to use the equals() method.

if (loader.equals("Klasse"))

answered May 13 '12 at 19:26

David Heffernan

601,492
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Good. Now i know i'm a little retarded :D Normally im using C# and so on.. Thanks for the help! – Styler2go May 13 '12 at 19:27
1

Yes, this is the classic C#/Java mistake. – David Heffernan May 13 '12 at 19:28
1

Or you could 'intern()' them first. – 11684 May 13 '12 at 19:31
@11684 You are joking aren't you? – David Heffernan May 13 '12 at 19:32
@David I thought the jvm had a string pool. Wouldn't references be equal if they were in a string pool? – skaz May 13 '12 at 19:32
@skaz only if the strings had been interned. – David Heffernan May 13 '12 at 19:33
I said you could, nou that it is a good solution. I always want to know such facts, so why shouldn't I say? – 11684 May 13 '12 at 19:35
Yes, its everytime interesting to see other ways, like "How i could have done it" – Styler2go May 13 '12 at 19:41
4

@11684: If you're going to include an option which you *know* isn't generally a good one, it's worth saying so when you mention it. – Jon Skeet May 13 '12 at 19:58

score 0 · Answer 2 · answered May 13 '12 at 19:27

0

There is a difference between identity (==) and equality (equals()). Identity tests for whether or not the object pointers are the same so almost never is correct. Equality tests whether or not the object "values" are the same, so it's almost always what you need instead.

answered May 13 '12 at 19:27

user268396

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Why does, for example, the Language C# use == for equality too? – Styler2go May 13 '12 at 19:28
2

@Styler2go Ask yourself when was the last time you want to compare two string references for identity? – David Heffernan May 13 '12 at 19:31
I think in C# the Java `==` would be `===`, isn't it that? – Styler2go May 13 '12 at 19:35

score 0 · Answer 3 · answered May 13 '12 at 19:29

String comparison should always be done with the equals method.

if(loader.equals("Klasse")) { .... }

This is because String is a class and by using '==' you check whether they are the same object, which they a not. Equals checks that the strings you are comparing are equal.

score 0 · Answer 4 · answered May 13 '12 at 23:28

0

if == or === does not work, use .equals

answered May 13 '12 at 23:28

Klinetel

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if () not working

4 Answers4