How would I compare a set of strings?

Question

i have a username and a password string. How can I compare them in Android? This is somewhat what I'm looking for:

if( user== username && pass == password){ then do this  }
else if(user[does not equal to]username && pass==password{ toast (invaild username.)}
else if(user==username && pass[does not equal] password{toast(invaild password)}
else{ toast [invaild login]}

I know that's not correct coding but the two "else if" statements is what I'm looking for. The rest is just to give a better understanding of what I'm trying to do.

The username is what's entered into a Edittext same with the Password so they are both String when i .getText.toString right?

First of all: strings have to be compared using `.equals()`, not `==`. As to what I believe is your question: don't tell the user whether his username or password is wrong. If you do so, it will encourage people to guess a username + password combination. Just displaying 'invalid username/password' should be enough. — Jeroen Vannevel, Dec 16 '13 at 00:52
Good thought, this is for work tho and the people their wont really have the time nor the knowledge for a gussing game. — Dakota Miller, Dec 16 '13 at 00:55
If you care about security you should not store passwords... — assylias, Dec 16 '13 at 01:00

score 2 · Accepted Answer · edited Dec 16 '13 at 01:11

2

To compare the text in strings use equals() e.g. pass.equals(password) rather than == which checks if two strings are the same object.

For "does not equal" you can negate the statement e.g. !pass.equals(password).

edited Dec 16 '13 at 01:11

Jeroen Vannevel

42,521
22
100
163

answered Dec 16 '13 at 00:49

splrs

2,404
2
18
28

This is not the issue at hand. – Jeroen Vannevel Dec 16 '13 at 00:50
Doesnt that just check objects-ints not String's? – Dakota Miller Dec 16 '13 at 00:50
1 moment, editing or deleting as necessary. – splrs Dec 16 '13 at 00:52
@DakotaMiller equals will work for comparing the values of the strings. – splrs Dec 16 '13 at 00:54
Ok i thought it was just for Object and ints. – Dakota Miller Dec 16 '13 at 00:56
http://docs.oracle.com/javase/7/docs/api/java/lang/String.html, the method is in there. However if you're not asking for the functionality to compare strings and I've misunderstood your question, then let me know and I'll happily remove this answer. – splrs Dec 16 '13 at 00:57
@JeroenVannevel If that was your downvote, do you think your comment still applies? – splrs Dec 16 '13 at 00:59
@splrs: it was indeed. I'm not sure anymore if it was warranted, I'll wait to see what Miller says. I'll retract it if this was the issue after all. – Jeroen Vannevel Dec 16 '13 at 01:01
I agree that initially it was entirely justified, now I'm not sure it is following the edit. Obviously your call though. – splrs Dec 16 '13 at 01:02
Since your answer was accepted I'm guessing this was just another case of the duplicates. I retracted my downvote. – Jeroen Vannevel Dec 16 '13 at 01:11
Thanks @JeroenVannevel, without the downvote I'd not have provided a useful answer, so it's appreciated. – splrs Dec 16 '13 at 01:12

score 0 · Answer 2 · edited Dec 26 '13 at 03:08

0

You could use pass.equal(password).

edited Dec 26 '13 at 03:08

apaderno

26,733
16
74
87

answered Dec 16 '13 at 00:49

user3105622

1
2

score 0 · Answer 3 · answered Dec 16 '13 at 00:55

Use the equals method for comparing strings.

if( user.equals(username) && pass.equals(password))
{
    then do this 
}
else if(!user.equals(username) && pass.equals(password)
{  
 Toast.makeText(this,"invalid username",Toast.LENGTH_SHORT).show();
}
else if(user.equals(username) && !pass.equals(password))
{
Toast.makeText(this,"invalid password",Toast.LENGTH_SHORT).show();
 }
else{ 
Toast.makeText(this,"Invalid login",Toast.LENGTH_SHORT).show(); 
}

score 0 · Answer 4 · answered Dec 16 '13 at 00:56

You want to use .equals(..) to compare Strings. Also, to do not logically, you can use !.

//define user, username
//define pass, password
if(user.equals(username) && pass.equals(password)){ 
    //then do this  
}
else if(!user.equals(username) && pass.equals(password)){
    //toast (invaild username.)
    Toast.makeText(getApplicationContext(), "invalid username", Toast.LENGTH_SHORT).show();
}
else if(user.equals(username) && !pass.equals(password)){
    //toast(invaild password)
    Toast.makeText(getApplicationContext(), "invalid password", Toast.LENGTH_SHORT).show();
}
else{ 
    //toast [invaild login]
    Toast.makeText(getApplicationContext(), "invalid login", Toast.LENGTH_SHORT).show();
}

Here are some sources on Toast:

http://www.mkyong.com/android/android-toast-example/

http://developer.android.com/guide/topics/ui/notifiers/toasts.html

How would I compare a set of strings?

4 Answers4