if statement doesn't work for string

Question

In my project, i read the text in NFC Tag, and i save it to String value. And if string value == given string , do something.

here is my code :

btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            try {
                if(nfcTag==null){
                    Toast.makeText(context, "Lütfen NFC Etiketini Okutunuz", Toast.LENGTH_SHORT).show();
                }else{
                    nfcString = read(nfcTag);  // this is the part i get the text with read function. i already define nfcString as String.
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

            textViewName.setText(nfcString); // it is working fine !

            String salak = textViewName.getText().toString();
            // i created new String because, i tried to get textViewName.getText().toString() , i tought it should be work, but it didn't 

            try {
                // this is the if statement which doesn't work..
                if ( salak == getName(position) ) {
                    // i also tried 
                    // nfcString  == getName(position)
                    // nfcString.toString()  == getName(position).toString()
                    // position thing is about spinner. i use spinner, it works fine also..

                    btn.setText("Girdin!");
                    yoklamaSend(getDersid(position));

                } else
                    Toast.makeText(context, "DERS GİRDİSİ BAŞARISIZ", Toast.LENGTH_LONG).show();
            }
            catch (Exception ee) {
                ee.printStackTrace();

            }
        }
    });

I can't understand why it is not working. NFC Tag is working fine, but whatever i do, i couldn't run if statement.

I get the NFC Tag Read code from sample of different app (which is working fine), here it is :

    private String read(Tag tag) throws UnsupportedEncodingException {

    Ndef ndef = Ndef.get(tag);
    NdefMessage ndefMessage = ndef.getCachedNdefMessage();
    NdefRecord[] records = ndefMessage.getRecords();
    for (NdefRecord ndefRecord : records) {
        if (ndefRecord.getTnf() == NdefRecord.TNF_WELL_KNOWN && Arrays.equals(ndefRecord.getType(), NdefRecord.RTD_TEXT)) {
            try {
                byte[] payload = ndefRecord.getPayload();
                String textEncoding = ((payload[0] & 128) == 0) ? "UTF-8" : "UTF-16";
                int languageCodeLength = payload[0] & 0063;
                return new String(payload, languageCodeLength + 1, payload.length - languageCodeLength - 1, textEncoding);
            } catch (UnsupportedEncodingException e) {
                Log.e("TAG", "Unsupported Encoding", e);
            }
        }
    }
    return null;
}

score 3 · Accepted Answer · edited May 23 '17 at 12:31

3

The correct way to compare strings is with .Equals(String).

Using the == compares to see if they are the same object in memory

See these links:

https://docs.oracle.com/javase/tutorial/java/data/comparestrings.html

How do I compare strings in Java?

Java String.equals versus ==

edited May 23 '17 at 12:31

Community

1
1

answered May 02 '16 at 19:40

Jeremy Barnes

657
4
15

1

thanks bro, i solved it after asked the question. i've been trying to fix it more than 2 hours. it was my stupid ignorance.. – Ahmet Özdemir May 02 '16 at 19:45

score 1 · Answer 2 · answered May 02 '16 at 19:40

1

Use equals function instead of == operator to compare Strings. The == operator checks whether the two operands are same object or not.

For example, use salak.equals(getName(position)) instead of salak == getName(position)

answered May 02 '16 at 19:40

jaibatrik

6,770
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so easy.. having no experience is too bad for codding.. thanks by the way – Ahmet Özdemir May 02 '16 at 19:45

score 0 · Answer 3 · answered May 02 '16 at 19:41

0

Try using equals() method instead of == in your if statement.

answered May 02 '16 at 19:41

Mussa

1,463
21
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1

it is shame to not knowing that.. – Ahmet Özdemir May 02 '16 at 19:46

if statement doesn't work for string

3 Answers3