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情况

我正在尝试编写一个执行一项非常简单任务的应用程序：当使用适当的 AAR 和 URI 检测到NFC标签时，它会启动应用程序，使用标签中的数据连接到指定的蓝牙无线电（由 NFC 标签指定) 并等待接受数据流，然后将其转换为字符串并显示在屏幕上。

当我当前运行应用程序时，它会立即退出并出现三个运行时异常。我希望它被动等待而不是关闭，并且我不理解运行时异常。

例外情况

  1. 无法恢复活动；空指针异常
  2. 解析标记（）；异常行 127
  3. onResume(); 第 83 行异常

编码

public class BlueNF extends Activity {

    private BluetoothDevice mBluetoothDevice = null;
    private BluetoothAdapter mBluetoothAdapter = null;
    private BluetoothSocket mBluetoothSocket = null;

    private NfcAdapter mNfcAdapter = null;

    private NdefMessage dashTag = null;

    private static final int REQUEST_ENABLE_BT = 3;
    private static final UUID SerialPortServiceClass_UUID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

    private InputStream iStream = null;

    public static String iValue = null;
    public final static String EXTRA_MESSAGE = "com.yogafarts.hackpsuproject.BlueNF.iValue";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //Set the content view
        setContentView(R.layout.activity_blue_nf);
        //Check for NFC
        mNfcAdapter = NfcAdapter.getDefaultAdapter(this);
        if (mNfcAdapter == null) {
            Toast.makeText(this, "NFC is not available", Toast.LENGTH_LONG).show();
            finish();
            return;
        }

        //Check for Bluetooth
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        if (mBluetoothAdapter == null) {
            Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_LONG).show();
            finish();
            return;
        }
    }

    @Override
    public void onStart() {
        super.onStart();

        if (!mBluetoothAdapter.isEnabled()) {
            Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
        }
    }

    public void onResume() {
        super.onResume();
        //IntentFilter ndefTag = new IntentFilter(NfcAdapter.ACTION_NDEF_DISCOVERED);

        //Get the current intent
        Intent dashTagIntent = getIntent();

        //Read extra intent data into tag object (Really just reading the NdefMessage into the dashTag object
        dashTag = dashTagIntent.getParcelableExtra(NfcAdapter.EXTRA_TAG);

        //Create a byte array of bluetooth hardware ID using ParseTag
        byte[] mBluetoothInfo = ParseTag(dashTag);


        //Create a bluetooth adapter object
        mBluetoothDevice = mBluetoothAdapter.getRemoteDevice(mBluetoothInfo);//Should be 0013EF00061A

        try {
            mBluetoothSocket = mBluetoothDevice.createRfcommSocketToServiceRecord(SerialPortServiceClass_UUID);
        }
        catch ( IOException e ) {
            Log.e( "Bluetooth Socket", "Bluetooth not available, or insufficient permissions" );
        }

        //Cancel discovery because it's resource intensive (if it's active)
        mBluetoothAdapter.cancelDiscovery();

        //Connect to the device
        try {
            mBluetoothSocket.connect();
            iStream = mBluetoothSocket.getInputStream();

            //System.out.println(iStream);
            //OutputStream oStream = mBluetoothSocket.getOutputStream();
        }
        catch ( IOException e ) {

            try { mBluetoothSocket.close();

            }
            catch ( IOException e2 ) {
                Log.e( "Bluetooth Socket", "IO Exception" );
            }
        }
        iValue = iStream.toString();
        viewMessage();
    }

    public byte[] ParseTag(NdefMessage ndef) {

        NdefRecord[] mNdef = ndef.getRecords();
        return mNdef[2].getPayload();
    }

    public void viewMessage() {
        Intent intent = new Intent(this, DisplayMessage.class);
        //TextView text = (TextView) findViewById(R.id.tv);
        String message = iValue;//text.getText().toString();
        intent.putExtra(EXTRA_MESSAGE, message);
        startActivity(intent);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.blue_n, menu);
        return true;
    }

}

以及在读取流后显示文本的活动......

public class DisplayMessage extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_display_message);
        TextView text = (TextView) findViewById(R.id.tv);
            text.setText(com.yogafarts.hackpsuproject.BlueNF.iValue);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.display_message, menu);
        return true;
    }
}
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0 回答 0