Null checking not working

Question

sorry if this is a low quality question, but still is a question :) here im using a simple in the eyes condition for checking EditText's null Being,

public String theuser=null;
public String thepass=null;

EditText  u=(EditText)findViewById(R.id.inputuser);
this.theuser = u.getText().toString();
EditText p =(EditText)findViewById(R.id.inputpassword);
this.thepass = p.getText().toString();

if ((theuser.equals(null))||(thepass.equals(null))){ 
    Toast.makeText(this,"Username and Password Cant Be Empty!",     
    Toast.LENGTH_SHORT).show();   
}else{
    Log.i("lifemate","did you click me ?!"+theuser+"  "+thepass);
    BusProvider.getInstance().post(SendRequestInfo());
}

but the null check seems to be not working ! i tried .equals(null) and .equals("") too still not working! do guys know why is that ?!

What do you mean by "seems not to be working"? (Hint: use `==` instead to check for nullity - or `.equals("")` to check for an empty string...) And *please* format your code more readably... — Jon Skeet, Jun 02 '14 at 08:23
@Jon Skeet...You should put it as answer to get the points :) — Opiatefuchs, Jun 02 '14 at 08:26
use TextUtils.isEmpty. It does check for empty strings and null values — Blackbelt, Jun 02 '14 at 08:30
:) :) awesome...is it possible that HE IS stackoverflow? :)...never seen so many points :) — Opiatefuchs, Jun 02 '14 at 08:36

score 3 · Answer 1 · answered Jun 02 '14 at 08:25

3

Comparison to null should be done using the == operator.

So use if (theuser==null || thepass == null).

answered Jun 02 '14 at 08:25

peter.petrov

38,363
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i forgot to write this is first that i have done :D but didnt work yet – user3694470 Jun 02 '14 at 08:37

Jens · Answer 2 · 2014-06-02T08:31:30.423

2

that if ((theuser.equals(null))||(thepass.equals(null))){

must be if ((theuser.equals(""))||(thepassequals(""))){

because getText() returns an empty string if there is no input. It not return null.

edited Jun 02 '14 at 08:31

answered Jun 02 '14 at 08:25

Jens

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score 0 · Answer 3 · answered Jun 02 '14 at 08:25

0

equals null is not applicable for the reference of your String object.

You need to use (mystring != null) to test the nullability.

answered Jun 02 '14 at 08:25

marshallino16

2,645
15
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score 0 · Answer 4 · answered Jun 02 '14 at 08:25

0

replace

if ((theuser.equals(null))||(thepass.equals(null)))

with

if (theuser==null||thepass==null)

answered Jun 02 '14 at 08:25

Macrosoft-Dev

2,195
1
12
15

score 0 · Accepted Answer · edited May 23 '17 at 11:50

Equals contract states that:

For any non-null reference value x, x.equals(null) should return false.

But when x is null this would cause a NullPointerException because you are trying to access a method of a null object.

In short use x == null rather than x.equals(null).

But in your case

You are testing the text value from a TextView. I would not expect this to be null, particulary as you call toString() on a CharSequence. So this will be just empty if anything, i.e. you can do this:

if ("".equals(theuser) || "".equals(thepass)) {

GovindRathod · Answer 6 · 2015-04-08T09:09:43.997

0

For checking the null in string android provide very good class over there

you just pass your string in

//check while for the null string. 
if(TextUtils.isEmpty("YOUR_STRING")){
 //perform operation. 
}

It will automatically handle NULL as well as EMPTY string.

edited Apr 08 '15 at 09:09

answered Jun 02 '14 at 08:37

GovindRathod

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Null checking not working

6 Answers6