MainActivity.kt

MainActivity.kt

package com.example.myapplication

import android.app.PendingIntent
import android.content.Intent
import android.content.IntentFilter
import android.nfc.NfcAdapter
import android.nfc.Tag
import android.os.Bundle
import android.util.Log
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.ui.Modifier
import androidx.compose.ui.tooling.preview.Preview
import com.example.myapplication.ui.theme.MyApplicationTheme

class MainActivity : ComponentActivity() {

    private var nfcAdapter: NfcAdapter? = null
    private lateinit var pendingIntent: PendingIntent
    private lateinit var intentFiltersArray: Array<IntentFilter>
    private lateinit var techListsArray: Array<Array<String>>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()

        // NFC setup
        nfcAdapter = NfcAdapter.getDefaultAdapter(this)
        if (nfcAdapter == null) {
            Log.e("NFC", "NFC not supported on this device")
        } else if (!nfcAdapter!!.isEnabled) {
            Log.e("NFC", "NFC is disabled")
        }

        // Create a PendingIntent to handle NFC tag discovery
        val intent = Intent(this, javaClass).apply {
            addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP)
        }
        pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_MUTABLE)

        // Create intent filters to handle NFC tag discovery
        // Change to ACTION_TAG_DISCOVERED to catch all tags
        val tagDetected = IntentFilter(NfcAdapter.ACTION_TAG_DISCOVERED)
        intentFiltersArray = arrayOf(tagDetected)

        // Setup tech lists to handle all tag technologies
        // We don't need to specify any tech lists for ACTION_TAG_DISCOVERED
        techListsArray = arrayOf()

        setContent {
            MyApplicationTheme {
                Scaffold(modifier = Modifier.fillMaxSize()) { innerPadding ->
                    Greeting(
                        name = "Android",
                        modifier = Modifier.padding(innerPadding)
                    )
                }
            }
        }
    }

    override fun onResume() {
        super.onResume()
        nfcAdapter?.enableForegroundDispatch(this, pendingIntent, intentFiltersArray, techListsArray)
    }

    override fun onPause() {
        super.onPause()
        nfcAdapter?.disableForegroundDispatch(this)
    }

    override fun onNewIntent(intent: Intent) {
        super.onNewIntent(intent)
        // Check for ACTION_TAG_DISCOVERED instead of ACTION_NDEF_DISCOVERED
        if (NfcAdapter.ACTION_TAG_DISCOVERED == intent.action) {
            val tag: Tag? = intent.getParcelableExtra(NfcAdapter.EXTRA_TAG)
            if (tag != null) {
                val tagId = tag.id
                val tagIdString = tagId.joinToString(":") { String.format("%02X", it) }
                Log.d("NFC", "Tag discovered with ID: $tagIdString")
            }
        }
    }
}

@Composable
fun Greeting(name: String, modifier: Modifier = Modifier) {
    Text(
        text = "Hello $name!",
        modifier = modifier
    )
}

@Preview(showBackground = true)
@Composable
fun GreetingPreview() {
    MyApplicationTheme {
        Greeting("Android")
    }
}