扫描 NFC 标签后出现 ArrayIndexOutOfBoundsException

Question

我正在尝试重建我的 NFC 标签阅读器

https://stackoverflow.com/questions/16071121/converting-existing-nfc-script-to-read-multiple-ndef-records

我收到以下错误：

 java.lang.ArrayIndexOutOfBoundsException: length=1; index=1

上线：

 NdefMessage msg2 = (NdefMessage) rawMsgs[1];

我了解该问题通常与尝试访问不存在的数组项有关，但是我真的不确定如何在以下实现中解决该问题。

附言

仅在扫描新的 NFC 标签时才会出现此问题。不过我注意到了一些非常有趣的事情......

如果我注释掉以下两行，应用程序不会崩溃并成功扫描标签！

// NdefMessage msg2 = (NdefMessage) rawMsgs[1];


 //  beamMsg2.setText(new String(msg.getRecords()[1].getPayload()));

来源：

public class Nfc extends Activity implements CreateNdefMessageCallback,
        OnNdefPushCompleteCallback {
    NfcAdapter mNfcAdapter;
    TextView beamMsg;
    TextView beamMsg2;
    private static final int MESSAGE_SENT = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.nfc);
        beamMsg = (TextView) findViewById(R.id.msg);
        beamMsg2 = (TextView) findViewById(R.id.msg_ID);
        beamMsg.setText("Peter Smith");
        beamMsg2.setText("123456");

        // Check for available NFC Adapter
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        if (mNfcAdapter == null) {
            beamMsg = (TextView) findViewById(R.id.msg);
            beamMsg2= (TextView) findViewById(R.id.msg_ID);

            beamMsg.setText("NFC is not available on this device.");
            beamMsg2.setText("NFC is not available on this device.");
        } else {
            // Register callback to set NDEF message
            mNfcAdapter.setNdefPushMessageCallback(this, this);
            // Register callback to listen for message-sent success
            mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
        }
    }

    public void submitClicked(View v)
    {
        Toast toast = Toast.makeText(getApplicationContext(), R.string.info,
                Toast.LENGTH_LONG);
        toast.show();
    }
    /**
     * Implementation for the CreateNdefMessageCallback interface
     */
    @Override
    public NdefMessage createNdefMessage(NfcEvent event) {
        NdefMessage msg = new NdefMessage(NdefRecord.createMime(
                beamMsg.getText()  .toString(), null));

        return msg;

    }

    public NdefMessage createNdefMessage_two(NfcEvent event) {
        NdefMessage msg2 = new NdefMessage(NdefRecord.createMime(
                beamMsg2.getText()  .toString(), null));

        return msg2;

    }




    /**
     * Implementation for the OnNdefPushCompleteCallback interface
     */
    @Override
    public void onNdefPushComplete(NfcEvent arg0) {
        // A handler is needed to send messages to the activity when this
        // callback occurs, because it happens from a binder thread
        mHandler.obtainMessage(MESSAGE_SENT).sendToTarget();
    }

    /** This handler receives a message from onNdefPushComplete */
    private final Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case MESSAGE_SENT:
                Toast.makeText(getApplicationContext(), "Message sent!", Toast.LENGTH_LONG).show();
                break;
            }
        }
    };

    @Override
    public void onResume() {
        super.onResume();
        // Check to see that the Activity started due to an Android Beam
        if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
            processIntent(getIntent());
        }
    }

    @Override
    public void onNewIntent(Intent intent) {
        // onResume gets called after this to handle the intent
        setIntent(intent);
    }

    /**
     * Parses the NDEF Message from the intent and prints to the TextView
     */
    void processIntent(Intent intent) {
        Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
                NfcAdapter.EXTRA_NDEF_MESSAGES);
        // only one message sent during the beam
        NdefMessage msg = (NdefMessage) rawMsgs[0];
        NdefMessage msg2 = (NdefMessage) rawMsgs[1];
        // record 0 contains the MIME type, record 1 is the AAR, if present
        beamMsg.setText(new String(msg.getRecords()[0].getPayload()));
        beamMsg2.setText(new String(msg.getRecords()[1].getPayload()));
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // If NFC is not available, we won't be needing this menu
        if (mNfcAdapter == null) {
            return super.onCreateOptionsMenu(menu);
        }
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
        return true;
    }

   // @Override
   // public boolean onOptionsItemSelected(MenuItem item) {
    //    switch (item.getItemId()) {
      //      case R.id.menu_settings:
        //        Intent intent = new Intent(Settings.ACTION_NFCSHARING_SETTINGS);
          //      startActivity(intent);
            //    return true;
         //   default:
           //     return super.onOptionsItemSelected(item);
       // }
    }
//}//}

回答后编辑：

public class Connect extends Activity implements CreateNdefMessageCallback,
        OnNdefPushCompleteCallback {
    NfcAdapter mNfcAdapter;
    TextView beamMsg;
    TextView beamMsg2;
    private static final int MESSAGE_SENT = 1;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.connect);
        beamMsg = (TextView) findViewById(R.id.msg);
        beamMsg2 = (TextView) findViewById(R.id.msg_ID);
        beamMsg.setText("Peter Smith");
        beamMsg2.setText("123456");

        // Check for available NFC Adapter
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        if (mNfcAdapter == null) {
            beamMsg = (TextView) findViewById(R.id.msg);
            beamMsg2= (TextView) findViewById(R.id.msg_ID);

            beamMsg.setText("NFC is not available on this device.");
            beamMsg2.setText("NFC is not available on this device.");
        } else {
            // Register callback to set NDEF message
            mNfcAdapter.setNdefPushMessageCallback(this, this);
            // Register callback to listen for message-sent success
            mNfcAdapter.setOnNdefPushCompleteCallback(this, this);
        }
    }

    public void submitClicked(View v)
    {
        Toast toast = Toast.makeText(getApplicationContext(), R.string.info,
                Toast.LENGTH_LONG);
        toast.show();
    }
    /**
     * Implementation for the CreateNdefMessageCallback interface
     */
    @Override
    public NdefMessage createNdefMessage(NfcEvent event) {
        NdefMessage msg = new NdefMessage(NdefRecord.createMime(
                beamMsg.getText()  .toString(), null));

        return msg;

    }

    public NdefMessage createNdefMessage_two(NfcEvent event) {
        NdefMessage msg2 = new NdefMessage(NdefRecord.createMime(
                beamMsg2.getText()  .toString(), null));

        return msg2;

    }




    /**
     * Implementation for the OnNdefPushCompleteCallback interface
     */
    @Override
    public void onNdefPushComplete(NfcEvent arg0) {
        // A handler is needed to send messages to the activity when this
        // callback occurs, because it happens from a binder thread
        mHandler.obtainMessage(MESSAGE_SENT).sendToTarget();
    }

    /** This handler receives a message from onNdefPushComplete */
    private final Handler mHandler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
            case MESSAGE_SENT:
                Toast.makeText(getApplicationContext(), "Message sent!", Toast.LENGTH_LONG).show();
                break;
            }
        }
    };

    @Override
    public void onResume() {
        super.onResume();
        // Check to see that the Activity started due to an Android Beam
        if (NfcAdapter.ACTION_NDEF_DISCOVERED.equals(getIntent().getAction())) {
            processIntent(getIntent());
        }
    }

    @Override
    public void onNewIntent(Intent intent) {
        // onResume gets called after this to handle the intent
        setIntent(intent);
    }

    /**
     * Parses the NDEF Message from the intent and prints to the TextView
     */
    void processIntent(Intent intent) {
        Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
                NfcAdapter.EXTRA_NDEF_MESSAGES);
    // only one message sent during the beam
    NdefMessage[] msg =  new NdefMessage[rawMsgs.length];
    for (int i = 0; i < msg.length; i++) {
        msg[i] = (NdefMessage) rawMsgs[i];
        // record 0 contains the MIME type, record 1 is the AAR, if present
        beamMsg[i].setText(new String(msg[i].getRecords()[1].getPayload()));
        beamMsg2[i].setText(new String(msg[i].getRecords()[1].getPayload()));
    }}

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // If NFC is not available, we won't be needing this menu
        if (mNfcAdapter == null) {
            return super.onCreateOptionsMenu(menu);
        }
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
        return true;
    }

   // @Override
   // public boolean onOptionsItemSelected(MenuItem item) {
    //    switch (item.getItemId()) {
      //      case R.id.menu_settings:
        //        Intent intent = new Intent(Settings.ACTION_NFCSHARING_SETTINGS);
          //      startActivity(intent);
            //    return true;
         //   default:
           //     return super.onOptionsItemSelected(item);
       // }
    }
//}//}

Answer 1

您的错误可能与您在此行发送给它的意图有关：

Parcelable[] rawMsgs = intent.getParcelableArrayExtra(NfcAdapter.EXTRA_NDEF_MESSAGES);

您用来创建意图的代码在哪里？

循环编辑：

要添加一个更像这样的循环：

Parcelable[] rawMsgs = intent.getParcelableArrayExtra(
            NfcAdapter.EXTRA_NDEF_MESSAGES);
// only one message sent during the beam
NdefMessage[] msg = = new NdefMessage[rawMsgs.length];
for (int i = 0; i < msg.length; i++) {
    msg[i] = (NdefMessage) rawMsgs[i];
    // record 0 contains the MIME type, record 1 is the AAR, if present
    beamMsg[i].setText(new String(msg[i].getRecords()[0].getPayload());
    beamMsg2[i].setText(new String(msg[i].getRecords()[1].getPayload()));
}

您还必须将 beamMsg 和 beamMsg2 初始化为 TextViews 数组。或者当然只是附加到文本字段并保持原样。

Answer 2

实际上，我不会使用 Java，但我会尝试。 我问你，你可以看看getParcelableArrayExtra()的实现。为什么他只返回一条消息而不是两条？