Question

I have a very specific problem here. I wrote an app to send messages to NFC chips, but it keeps crashing when I press the button. The editor I use, Eclipse, doesn’t give any errors or warnings, so it’s not an error in the code.

The thing that I find very, very strange is that it crashes despite the try/catch block containing all the code. The part where it launches and checks if NFC is enabled works just fine, but pressing “Write” just makes the app crash:

the application Tag Writer (process com.harold.tag.writer) has stopped unexpectedly.

Can you guys help me out here??

if you need any other information please ask.

package com.harold.tag.writer;

import java.util.Locale;

import android.app.Activity;
import android.content.Intent;
import android.nfc.NdefMessage;
import android.nfc.NdefRecord;
import android.nfc.NfcAdapter;
import android.nfc.Tag;
import android.nfc.tech.Ndef;
import android.nfc.tech.NdefFormatable;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import com.google.common.base.Charsets;
import com.google.common.primitives.Bytes;

public class Main extends Activity implements OnClickListener {

EditText etUser;
Button bWrite;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    initialise();
}

private void initialise(){

    nfcsettings();

    etUser = (EditText)findViewById(R.id.etTag);
    bWrite = (Button)findViewById(R.id.bWrite);

    bWrite.setOnClickListener(this);

}

public void onClick(View v) {
    try
    {
        //initialize nfc part
        nfcsettings();
        Intent intent = this.getIntent();
        Tag tag = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG);
        writeTag(tag);   
    }
    catch (Exception e){
        Toast.makeText(getBaseContext(), "Button clicking", Toast.LENGTH_SHORT).show();
    }
}

private void writeTag(Tag tag){
    try
    {
    nfcsettings();
    Locale locale = Locale.ROOT;
    final byte[] langBytes = locale.getLanguage().getBytes(Charsets.US_ASCII);
    final byte[] textBytes = etUser.toString().getBytes(Charsets.UTF_8);
    final int utfBit = 0;
    final char status = (char)(utfBit + langBytes.length);
    final byte[] data = Bytes.concat(new byte[] {(byte) status}, langBytes, textBytes);
    NdefRecord record = new NdefRecord(NdefRecord.TNF_WELL_KNOWN, NdefRecord.RTD_TEXT, new byte[0], data);


        NdefRecord[] records = {record};
        NdefMessage message = new NdefMessage(records);
        Ndef ndef = Ndef.get(tag);
        if (ndef != null) {
            ndef.connect();
            ndef.writeNdefMessage(message);
        } else {
            NdefFormatable format = NdefFormatable.get(tag);
            if (format != null) {
                format.connect();
                format.format(message);
            }           
        }
    }
    catch (Exception e)
    {
        //Display toast when there is a write error
        Toast.makeText(getBaseContext(), "Tag write unsuccessful.", Toast.LENGTH_SHORT).show();
    }
}

private void nfcsettings(){

    if(!NfcAdapter.getDefaultAdapter(this).isEnabled()){
        Toast.makeText(getApplicationContext(), "Please activate NFC and press Back to return to the application!", Toast.LENGTH_LONG).show();
        startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
    }
}
}

EDIT: i found that my problem lies in these lines:

import com.google.common.base.Charsets;
import com.google.common.primitives.Bytes;

The imports mentioned above are apparently not exported along with the rest of the app. I have Guava 9 included in my build path, but that doesn’t do the trick… How do i include the Charsets and Bytes imports in my app???

EDIT: SOLVED!!

Turns out, adding the guavalib.jar file from the default android-sdk to my project’s lib folder does the trick.

Answer 1

Turns out, adding the guavalib.jar file from the default android-sdk to my project’s lib folder does the trick.