我正在开发一个应用程序，我有一个按钮，它会显示一个对话框，它会找到蓝牙设备。
它工作正常，但是如果我在此活动中按下de back按钮，而不是返回主活动，则会销毁它。
对话框活动与BluetoothChat示例中的相同。这是主要活动的代码：
/*********************
*
* ONCREATE
*
********************/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final Button button1 = (Button) findViewById(R.id.button1);
final Button button2 = (Button) findViewById(R.id.button2);
/**Call to the Configuration activity*/
button2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
lanzarConfiguracion (null);
}
});
/**Call to the DeviceList activity*/
button1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
lanzarBusqueda (null);
}
});
GlobalVar.mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if (GlobalVar.mBluetoothAdapter == null) {
Toast.makeText(this, "Bluetooth is not available", Toast.LENGTH_LONG).show();
finish();
return;
}
}
/*********************
*
* ONSTART
*
********************/
@Override
public void onStart() {
super.onStart();
if (!GlobalVar.mBluetoothAdapter.isEnabled()) {
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, GlobalVar.REQUEST_ENABLE_BT);
}
else {
if (GlobalVar.mTransmission == null) setupCaller();
}
}
/*********************
*
* ONDESTROY
*
********************/
@Override
public void onDestroy() {
super.onDestroy();
/**Stop the Bluetooth chat services*/
if (GlobalVar.mTransmission != null) GlobalVar.mTransmission.stop();
}
/*********************
*
* OPTIONS
*
********************/
@Override
public boolean onCreateOptionsMenu(Menu menu) {
/**Inflate the menu; this adds items to the action bar if it is present.*/
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.info:
lanzarInfo(null);
break;
case R.id.config:
lanzarConfiguracion(null);
break;
}
return true; /** true -> consumimos el item, no se propaga*/
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case GlobalVar.REQUEST_CONNECT_DEVICE:
/**When DeviceListActivity returns with a device to connect*/
if (resultCode == Activity.RESULT_OK) {
connectDevice(data);
}
case GlobalVar.REQUEST_ENABLE_BT:
/**When the request to enable Bluetooth returns*/
if (resultCode == Activity.RESULT_OK) {
/**Bluetooth is now enabled, so set up a chat session*/
setupCaller();
} else {
/**User did not enable Bluetooth or an error occurred*/
Toast.makeText(this, R.string.bt_not_enabled_leaving, Toast.LENGTH_SHORT).show();
finish();
}
break;
}
}
private void connectDevice(Intent data) {
/**Get the device MAC address*/
String address = data.getExtras().getString(DeviceListDialog.EXTRA_DEVICE_ADDRESS);
/**Get the BluetoothDevice object*/
BluetoothDevice device = GlobalVar.mBluetoothAdapter.getRemoteDevice(address);
/**Attempt to connect to the device*/
try{
GlobalVar.mTransmission.connect(device);
}catch(Exception ex) {
}
}
private final void setStatus(int resId) {
final ActionBar actionBar = getActionBar();
actionBar.setSubtitle(resId);
}
private final void setStatus(CharSequence subTitle) {
final ActionBar actionBar = getActionBar();
actionBar.setSubtitle(subTitle);
}
/**
* The Handler that gets information back from the Transmission
*/
public final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case GlobalVar.MESSAGE_STATE_CHANGE:
switch (msg.arg1) {
case GlobalVar.STATE_CONNECTED:
setStatus(getString(R.string.title_connected_to, GlobalVar.mConnectedDeviceName));
GlobalVar.mCommunicationArrayAdapter.clear();
break;
case GlobalVar.STATE_CONNECTING:
setStatus(R.string.title_connecting);
break;
case GlobalVar.STATE_LISTEN:
case GlobalVar.STATE_NONE:
setStatus(R.string.title_not_connected);
break;
}
break;
case GlobalVar.MESSAGE_WRITE:
byte[] writeBuf = (byte[]) msg.obj;
/**construct a string from the buffer*/
String writeMessage = new String(writeBuf);
GlobalVar.mCommunicationArrayAdapter.add("Me: " + writeMessage);
break;
case GlobalVar.MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
/**construct a string from the valid bytes in the buffer*/
String readMessage = new String(readBuf, 0, msg.arg1);
GlobalVar.mCommunicationArrayAdapter.add(GlobalVar.mConnectedDeviceName+": " + readMessage);
break;
case GlobalVar.MESSAGE_DEVICE_NAME:
/**save the connected device's name*/
GlobalVar.mConnectedDeviceName = msg.getData().getString(GlobalVar.DEVICE_NAME);
Toast.makeText(getApplicationContext(), "Connected to " + GlobalVar.mConnectedDeviceName, Toast.LENGTH_SHORT).show();
break;
case GlobalVar.MESSAGE_TOAST:
Toast.makeText(getApplicationContext(), msg.getData().getString(GlobalVar.TOAST), Toast.LENGTH_SHORT).show();
break;
}
}
};
public void setupCaller() {
/**Initialize the Transmission to perform bluetooth connections*/
GlobalVar.mTransmission = new Transmission(this, mHandler);
/**Initialize the array adapter here for avoid errors with the Handler above*/
//GlobalVar.mCommunicationArrayAdapter = new ArrayAdapter<String>(this, R.layout.message);
}
/*********************
*
* INTENTS
*
********************/
public void lanzarConfiguracion (View view) {
Intent i = new Intent (this, Configuration.class);
startActivity(i);
}
public void lanzarInfo (View view) {
Intent i = new Intent(this, Info.class);
startActivity(i);
}
public void lanzarBusqueda (View view) {
Intent serverintent = new Intent(this, DeviceListDialog.class);
startActivityForResult(serverintent, GlobalVar.REQUEST_CONNECT_DEVICE);
}
}
答案 0 :(得分：1)
您在
之前忘记了break声明
case GlobalVar.REQUEST_ENABLE_BT:
在这种情况下继续执行，并且到达finish()语句，因为后退的默认RESULT_CODE为Activity.RESULT_CANCEL。