java - 将蓝牙的 Mac 地址传递给其他 Activity

Question

debug image here 蓝牙Activity.Java [调试图像2][2]

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.bluetooth_main);
        //myLabel = (TextView)findViewById(R.id.label);
        toggleButton = (ToggleButton) findViewById(R.id.toggleButton);
        listview = (ListView) findViewById(R.id.listView);
        // ListView Item Click Listener
        listview.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                // ListView Clicked item value
                String  itemValue = (String) listview.getItemAtPosition(position);
                Toast.makeText(getApplicationContext(), "clicked", Toast.LENGTH_LONG).show();
                String MAC = itemValue.substring(itemValue.length() - 17);
                Intent intent = new Intent(getApplicationContext(),Bluetooth_dataDisplay.class);
                intent.putExtra("MAC",MAC);
                startActivity(intent);
                //BluetoothDevice bluetoothDevice = mBluetoothAdapter.getRemoteDevice(MAC);
                // Initiate a connection request in a separate thread
                //ConnectingThread t = new ConnectingThread(bluetoothDevice);
                //t.start();
            }
        });

        adapter = new ArrayAdapter
                (this,android.R.layout.simple_list_item_1);
        listview.setAdapter(adapter);

        //verify bluetooth is supported on the device
        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        // Device does not support Bluetooth
        if (mBluetoothAdapter == null) {
        }

    }//end oncreate

Bluetooth_datadisplay.Java bluetooth_datadisplay image

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.bluetooth_datadisplay);

        myLabel = (TextView)findViewById(R.id.label);

        String MAC = getIntent().getStringExtra("MAC");

        BluetoothDevice bluetoothDevice = mAdapter.getRemoteDevice(MAC);

        // Initiate a connection request in a separate thread
        ConnectingThread t = new ConnectingThread(bluetoothDevice);

        t.start();

    }//end oncreate

错误

尝试在空对象引用上调用虚拟方法“android.bluetooth.BluetoothDevice android.bluetooth.BluetoothAdapter.getRemoteDevice(java.lang.String)”

您好，我尝试将蓝牙的 Mac 地址传递给蓝牙数据显示器。但我得到了上面的错误。谁能向我解释一下出了什么问题吗？谢谢你!

Answer 1

您尚未定义mAdapter的对象。

BluetoothAdapter mAdapter = BluetoothAdapter.getDefaultAdapter();    
BluetoothDevice bluetoothDevice = mAdapter.getRemoteDevice(MAC);

希望这对您有帮助。