String comparison not working in android

Question

I am trying to compare two string in my application but it fails to compare. I don't know why it fails.

    public void processFinish(String output) {
            // TODO Auto-generated method stub
            //Toast.makeText(getApplicationContext(), output,Toast.LENGTH_LONG).show();

            String check="false";
            if(output==check){
                     //doing something here
                }else{
                    //something here
                }
   }

the string object output has the value "false" but always the else block is executed why? I Tried by changing the output=="false" to

output.equals(check)
output.equalsIgnoreCase(check)
output.contentEquals(check)

nothings works...

try like this `output.trim().equals(check)` ... and see if it holds true — CRUSADER, Mar 13 '14 at 07:58
have you checked the spelling of `false` in variable `output`? — DroidDev, Mar 13 '14 at 07:59
Add this `Log.d("MYAPP", "X" + output + ": X" + check + "X");` without the trim(), your mistake will be clear. — Simon, Mar 13 '14 at 08:11
@Simon the question that already has an answer doesn't explain me about the trim() then why i have these down grades :@ — dharanbro, Mar 13 '14 at 08:30

Bhanu Sharma · Accepted Answer · 2014-03-13T08:04:25.100

12

public void processFinish(String output) {
            // TODO Auto-generated method stub
            //Toast.makeText(getApplicationContext(), output,Toast.LENGTH_LONG).show();

            String check="false";
            if(output.trim().equals(check.trim())){
                     //doing something here
                }else{
                    //something here
                }
}

your string getting some unwanted blank space from method trim() remove starting and end blank space :) and .equals is a object class method which compare two string :)

edited Mar 13 '14 at 08:04

answered Mar 13 '14 at 07:57

Bhanu Sharma

5,135
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thanks.working fine. but can you explain me what is actually happening there?? – dharanbro Mar 13 '14 at 08:01
your string getting some unwanted blank space from method trim() remove starting and end blank space :) and .equals is a object class method which compare two string :) – Bhanu Sharma Mar 13 '14 at 08:02
@DharanBro what is check. Is there any spaces?? – Raghunandan Mar 13 '14 at 08:02
1

@BhanuSharma add the explanation to your post. – Raghunandan Mar 13 '14 at 08:03
@Raghunandan see dude i already added – Bhanu Sharma Mar 13 '14 at 08:05
@DharanBro see i already added all explanation dude so have u clear what mistake u did – Bhanu Sharma Mar 13 '14 at 08:08
Nice ans @BhanuSharma... you really deserve an upvote. – Vineet Singh Jun 29 '14 at 06:05
no its very common @VineetSingh in thz no need to experience just some staring logic and that's it – Bhanu Sharma Jun 29 '14 at 07:57

Hamid Shatu · Answer 2 · 2014-03-13T08:05:03.373

1

Since instances of String are object, so you can't comparison two objects with ==. To comparison two String, you have to use equals() or equalIgnoreCase() method.

Replace this

if(output==check){
    //doing something here
}else{
    //something here
}

with...

if(output.equals(check)){
    //doing something here
}else{
    //something here
}

edited Mar 13 '14 at 08:05

answered Mar 13 '14 at 07:57

Hamid Shatu

9,664
4
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score 1 · Answer 3 · answered Mar 13 '14 at 07:58

1

try the following

         if(output.contains(check)== true{
                 //doing something here
            }else{
                //something here
            }

answered Mar 13 '14 at 07:58

WISHY

11,067
25
105
197

i even used trim(), it didnt work. contains() did the trick – M. Usman Khan May 03 '21 at 20:01

score 0 · Answer 4 · answered Mar 13 '14 at 07:57

0

I think output.equals(check) must works

Or your description maybe not correct.May it is not a string of "false" but "false "?

First ,check their length,then use output.trim().equals(check).

answered Mar 13 '14 at 07:57

tianwei

1,859
1
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String comparison not working in android

4 Answers4