Java conditional statement

Question

Possible Duplicate:
Java String.equals versus ==

I am using jcreator to practice java language. I came up with a conditional statement in which if the user input is = "test" it will print an "okay!" message. This is my code:

class conditional {

    public static void main (String[] args) {

        Scanner user_input = new Scanner(System.in);

        String username;
        System.out.print("username: ");
        username = user_input.next();
            if (username == "test") {
                System.out.println("okay");
                    }
                    else {
                                    System.out.println("not okay");
    }
}

The above code does not show any error, it does not display the "okay" && "not okay" message either. I am not sure what's wrong with my logic.

always use .equals() for string == for reference comparability — Dinup Kandel, Sep 05 '12 at 05:58

score 3 · Answer 1 · answered Sep 05 '12 at 05:57

3

Strings should be compared using .equals rather than ==. This is the case for all non-primitive comparisons. For example, you would compare two int fields with ==, but because Strings are not primitive, .equals is the correct choice.

if (username.equals("test")) {

answered Sep 05 '12 at 05:57

FThompson

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when and how do you use the ==? – user1645034 Sep 05 '12 at 06:39

score 1 · Answer 2 · answered Sep 05 '12 at 05:57

1

You should use String.equals here.

if (username.equals("test")) {

Otherwise, you're comparing the identities of the objects rather than their semantics. In fact, you have two separate Strings here, which satisfy semantic equality.

answered Sep 05 '12 at 05:57

obataku

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score 0 · Answer 3 · answered Sep 05 '12 at 06:03

0

Or If you want to use == do username.intern(); Then you can use ==.

Note: Not a recommended approch just for FYI.

answered Sep 05 '12 at 06:03

Amit Deshpande

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Not `username.intern();` -- that is a statement. You need to use the result of `username.intern()` in your comparison. That all being said, internalized strings are stored in a special part of the heap and are exempt from garbage collection. As a result, if the `String` internally holds a reference to e.g. a larger `char[]` (often the case with `String.substring` results), you can potentially be wasting quite a bit of memory without realizing it. – obataku Sep 05 '12 at 06:06

score 0 · Accepted Answer · answered Sep 05 '12 at 06:10

0

as @veer said, you can use equalsIgnoreCase / equals

if (username.equals("test")) { ... }

Or

You can use compareToIgnoreCase / compareTo

if (username.compareTo("test")==0) { ... }

answered Sep 05 '12 at 06:10

Chandra Sekhar

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mssb · Answer 5 · 2012-09-05T06:20:19.510

0

To compare string you need to use .equals() method and also if you need ignore the case of the letters in the String you can use .equalsIgnoreCase()

 if (username.equals("test")){

 }
 else{

 }

edited Sep 05 '12 at 06:20

answered Sep 05 '12 at 06:13

mssb

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score 0 · Answer 6 · answered Sep 05 '12 at 06:27

It will work if you do it like this:

import java.util.Scanner;

class Conditional {
    public static void main(String[] args) {
        Scanner user_input = new Scanner(System.in);
        String username;

        System.out.print("username: ");
        username = user_input.next();

        if (username.equals("test")) {
            System.out.println("okay");
        } else {
            System.out.println("not okay");
        }

        user_input.close();
    }
}

A few remarks:

Class names should start with an upper case.
Use equals to compare Strings.
You state that no result is printed at all. You will have to click in the console to type your answer and end the input with Enter.

Java conditional statement

6 Answers6

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