1
私はAndroidアプリの開発では初めてです。これは、AndroidデバイスをBLEデバイス（マイクロコントローラと通信する）に話しかける最初の試みです。目標は、マイクロコントローラにLEDを点灯させるために、この例では文字列「緑」または「青」をバイトに変換した値を送信することです。Android BLE NullPointerExceptionは、特性を書こうとしたとき
私はBluetoothに精通していないので、私はいくつかのコードをまとめるのに役立つさまざまな情報源をオンラインで探しています。私はデバイスに接続されている点に到達すると、信号を送信しようとすると、今、私はこのエラーコードを取得する：
のjava.lang.NullPointerException：仮想メソッドを呼び出すための試み「ブールのandroid.bluetooth com.example.andres.battle_bots.DeviceControlActivity.makeChange（DeviceControlActivity.java:366）com.example.andres.battle_bots.DeviceControlActivity.access $ 800（DeviceControlActivity。）でのヌルオブジェクト参照の.BluetoothGattCharacteristic.setValue（byte []） java：52）com.example.andres.battle_bots.DeviceControlActivity $ 3.onClick（DeviceControlActivity.java:151）
I私がそれらを使用する前に使用している変数をインスタンス化し、例外がスローされているので、私は何が欠けているのか分かりません。私が適応しているコードを誤解している可能性があります。私はこれまでに2つのアクティビティを持っていました。デバイスと接続をスキャンするDeviceScanActivityと、メインデバイスとの対話が発生してエラーが発生するDeviceControlActivityがあります。コードは次のとおりです。
import android.app.Activity;
import android.bluetooth.BluetoothGattCharacteristic;
import android.bluetooth.BluetoothGattService;
import android.content.BroadcastReceiver;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ExpandableListView;
import android.widget.ImageButton;
import android.widget.SeekBar;
import android.widget.SimpleExpandableListAdapter;
import android.widget.TextView;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.UUID;
public class DeviceControlActivity extends Activity {
private final static String TAG = DeviceControlActivity.class.getSimpleName();
public static final String EXTRAS_DEVICE_NAME = "DEVICE_NAME";
public static final String EXTRAS_DEVICE_ADDRESS = "DEVICE_ADDRESS";
private int[] RGBFrame = {0, 0, 0};
private TextView isSerial;
private TextView mConnectionState;
private TextView mDataField;
private String mDeviceName;
private String mDeviceAddress;
// private ExpandableListView mGattServicesList;
private BluetoothLeService mBluetoothLeService;
private boolean mConnected = false;
private BluetoothGattCharacteristic characteristicTX;
private BluetoothGattCharacteristic characteristicRX;
public final static UUID HM_RX_TX =
UUID.fromString(SampleGattAttributes.HM_RX_TX);
private final String LIST_NAME = "NAME";
private final String LIST_UUID = "UUID";
// Code to manage Service lifecycle.
private final ServiceConnection mServiceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder service) {
mBluetoothLeService = ((BluetoothLeService.LocalBinder) service).getService();
if (!mBluetoothLeService.initialize()) {
Log.e(TAG, "Unable to initialize Bluetooth");
finish();
}
// Automatically connects to the device upon successful start-up initialization.
mBluetoothLeService.connect(mDeviceAddress);
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
mBluetoothLeService = null;
}
};
// Handles various events fired by the Service.
// ACTION_GATT_CONNECTED: connected to a GATT server.
// ACTION_GATT_DISCONNECTED: disconnected from a GATT server.
// ACTION_GATT_SERVICES_DISCOVERED: discovered GATT services.
// ACTION_DATA_AVAILABLE: received data from the device. This can be a result of read
// or notification operations.
private final BroadcastReceiver mGattUpdateReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (BluetoothLeService.ACTION_GATT_CONNECTED.equals(action)) {
mConnected = true;
updateConnectionState(R.string.connected);
invalidateOptionsMenu();
} else if (BluetoothLeService.ACTION_GATT_DISCONNECTED.equals(action)) {
mConnected = false;
updateConnectionState(R.string.disconnected);
invalidateOptionsMenu();
clearUI();
} else if (BluetoothLeService.ACTION_GATT_SERVICES_DISCOVERED.equals(action)) {
// Show all the supported services and characteristics on the user interface.
displayGattServices(mBluetoothLeService.getSupportedGattServices());
} else if (BluetoothLeService.ACTION_DATA_AVAILABLE.equals(action)) {
displayData(intent.getStringExtra(mBluetoothLeService.EXTRA_DATA));
}
}
};
private void clearUI() {
// mDataField.setText(R.string.no_data);
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final Intent intent = getIntent();
mDeviceName = intent.getStringExtra(EXTRAS_DEVICE_NAME);
mDeviceAddress = intent.getStringExtra(EXTRAS_DEVICE_ADDRESS);
getActionBar().setTitle(mDeviceName);
getActionBar().setDisplayHomeAsUpEnabled(true);
Intent gattServiceIntent = new Intent(this, BluetoothLeService.class);
bindService(gattServiceIntent, mServiceConnection, BIND_AUTO_CREATE);
ImageButton U1 = (ImageButton) findViewById(R.id.up_btn1);
U1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
if(mBluetoothLeService != null) {
String codeGreen = "green";
makeChange(codeGreen);
}
}
});
ImageButton R1 = (ImageButton) findViewById(R.id.right_btn1);
R1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
ImageButton D1 = (ImageButton) findViewById(R.id.down_btn1);
D1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
ImageButton L1 = (ImageButton) findViewById(R.id.left_btn1);
L1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
ImageButton U2 = (ImageButton) findViewById(R.id.up_btn2);
U2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(mBluetoothLeService != null) {
String codeBlue = "blue";
makeChange(codeBlue);
}
}
});
ImageButton R2 = (ImageButton) findViewById(R.id.right_btn2);
R2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
ImageButton D2 = (ImageButton) findViewById(R.id.down_btn2);
D2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
ImageButton L2 = (ImageButton) findViewById(R.id.left_btn2);
L2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
ImageButton BLE = (ImageButton) findViewById(R.id.ble_btn);
BLE.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
Intent intent = new Intent(DeviceControlActivity.this, com.example.andres.battle_bots.DeviceScanActivity.class);
startActivity(intent);
}
});
ImageButton Options = (ImageButton) findViewById(R.id.options_btn);
Options.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Do something with Bluetooth
}
});
// Sets up UI references.
// ((TextView) findViewById(R.id.device_address)).setText(mDeviceAddress);
// mConnectionState = (TextView) findViewById(R.id.connection_state);
// is serial present?
// isSerial = (TextView) findViewById(R.id.isSerial);
/*
mDataField = (TextView) findViewById(R.id.data_value);
mRed = (SeekBar) findViewById(R.id.seekRed);
mGreen = (SeekBar) findViewById(R.id.seekGreen);
mBlue = (SeekBar) findViewById(R.id.seekBlue);
readSeek(mRed, 0);
readSeek(mGreen, 1);
readSeek(mBlue, 2);
*/
}
@Override
protected void onResume() {
super.onResume();
registerReceiver(mGattUpdateReceiver, makeGattUpdateIntentFilter());
if (mBluetoothLeService != null) {
final boolean result = mBluetoothLeService.connect(mDeviceAddress);
Log.d(TAG, "Connect request result=" + result);
}
}
@Override
protected void onPause() {
super.onPause();
unregisterReceiver(mGattUpdateReceiver);
}
@Override
protected void onDestroy() {
super.onDestroy();
unbindService(mServiceConnection);
mBluetoothLeService = null;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.gatt_services, menu);
if (mConnected) {
menu.findItem(R.id.menu_connect).setVisible(false);
menu.findItem(R.id.menu_disconnect).setVisible(true);
} else {
menu.findItem(R.id.menu_connect).setVisible(true);
menu.findItem(R.id.menu_disconnect).setVisible(false);
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.menu_connect:
mBluetoothLeService.connect(mDeviceAddress);
return true;
case R.id.menu_disconnect:
mBluetoothLeService.disconnect();
return true;
case android.R.id.home:
onBackPressed();
return true;
}
return super.onOptionsItemSelected(item);
}
private void updateConnectionState(final int resourceId) {
runOnUiThread(new Runnable() {
@Override
public void run() {
// mConnectionState.setText(resourceId);
}
});
}
private void displayData(String data) {
if (data != null) {
mDataField.setText(data);
}
}
// Demonstrates how to iterate through the supported GATT Services/Characteristics.
// In this sample, we populate the data structure that is bound to the ExpandableListView
// on the UI.
private void displayGattServices(List<BluetoothGattService> gattServices) {
if (gattServices == null) return;
String uuid = null;
String unknownServiceString = getResources().getString(R.string.unknown_service);
ArrayList<HashMap<String, String>> gattServiceData = new ArrayList<HashMap<String, String>>();
// Loops through available GATT Services.
for (BluetoothGattService gattService : gattServices) {
HashMap<String, String> currentServiceData = new HashMap<String, String>();
uuid = gattService.getUuid().toString();
currentServiceData.put(
LIST_NAME, SampleGattAttributes.lookup(uuid, unknownServiceString));
// If the service exists for HM 10 Serial, say so.
if (SampleGattAttributes.lookup(uuid, unknownServiceString) == "HM 10 Serial") {
// isSerial.setText("Yes, serial :-)");
} else {
// isSerial.setText("No, serial :-(");
}
currentServiceData.put(LIST_UUID, uuid);
gattServiceData.add(currentServiceData);
// get characteristic when UUID matches RX/TX UUID
characteristicTX = gattService.getCharacteristic(BluetoothLeService.UUID_HM_RX_TX);
characteristicRX = gattService.getCharacteristic(BluetoothLeService.UUID_HM_RX_TX);
}
}
private static IntentFilter makeGattUpdateIntentFilter() {
final IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(BluetoothLeService.ACTION_GATT_CONNECTED);
intentFilter.addAction(BluetoothLeService.ACTION_GATT_DISCONNECTED);
intentFilter.addAction(BluetoothLeService.ACTION_GATT_SERVICES_DISCOVERED);
intentFilter.addAction(BluetoothLeService.ACTION_DATA_AVAILABLE);
return intentFilter;
}
// on change of bars write char
private void makeChange(String str) {
Log.d(TAG, "Sending result=" + str);
final byte[] tx = str.getBytes();
if (mConnected) {
characteristicTX.setValue(tx);
mBluetoothLeService.writeCharacteristic(characteristicTX);
mBluetoothLeService.setCharacteristicNotification(characteristicRX, true);
Log.d(TAG,"Success");
}
else
{
Log.d(TAG,"Failed");
}
}
}
何か助けていただければ幸いです。あなたは確かに私の人生を楽にしてくれるでしょうし、Android/Bluetooth開発を始めている人たちを助けるかもしれません。 ありがとう！