Java 发送按钮使应用程序崩溃

此应用程序通过

Wi-Fi

direct

Api

发送文本消息。为此，我使用了内置API。代码正在运行，发现设备也存在问题，但按下发送按钮时发送消息

我也尝试过这个解决方案： 但只要按下发送按钮，应用程序仍然会崩溃

main活动

：

public class MainActivity extends AppCompatActivity{
Switch switch1;
Button btnOnOff, btnSend, btnDiscover;
ListView listView;
TextView read_msg_box, connectionStatus;
EditText writeMsg;
WifiManager wifiManager;
WifiP2pManager.Channel mChannel;
WifiP2pManager mManager;
BroadcastReceiver mReceiver;
IntentFilter mIntentFilter;
List <WifiP2pDevice> peers = new ArrayList<WifiP2pDevice>();
String[] deviceNameArray;
WifiP2pDevice[] deviceArray;
static final int MESSAGE_READ = 1;
ServerClass serverClass;
ClientClass clientClass;
SendReceive sendReceive;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    initialWork();
    exqListner();
}

Handler handler = new Handler(new Handler.Callback() {
    @Override
    public boolean handleMessage(Message msg) {
        switch(msg.what){
            case MESSAGE_READ:
                byte[] readbuff = (byte[]) msg.obj;
                String tempMsg = new String(readbuff, 0, msg.arg1);
                read_msg_box.setText(tempMsg);
                break;
        }
        return true;
    }
});
private void exqListner() {
    btnOnOff.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(wifiManager.isWifiEnabled()){
                wifiManager.setWifiEnabled(false);
                btnOnOff.setText("ON");
            }else{
                wifiManager.setWifiEnabled(true);
                btnOnOff.setText("OFF");
            }
        }
    });

    btnDiscover.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {
                @Override
                public void onSuccess() {
                    connectionStatus.setText("Discovering started");
                }

                @Override
                public void onFailure(int reason) {
                    connectionStatus.setText("Discovering starting failed");
                }
            });
        }
    });

    btnSend.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String msg = writeMsg.getText().toString();
            byte[] bytes =msg.getBytes();
            btnSend.setVisibility(View.INVISIBLE);
            if(connectionStatus.equals("Host")) {
                serverClass.writeData(bytes);
            } else {
                clientClass.writeData(bytes);
            }

        }
    });

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int i, long l) {
            final WifiP2pDevice device = deviceArray[i];
            WifiP2pConfig config = new WifiP2pConfig();
            config.deviceAddress = device.deviceAddress;
            mManager.connect(mChannel, config, new WifiP2pManager.ActionListener() {
                @Override
                public void onSuccess() {
                    Toast.makeText(getApplicationContext(), "Connected to "+device.deviceName, Toast.LENGTH_SHORT).show();
                }

                @Override
                public void onFailure(int reason) {
                    Toast.makeText(getApplicationContext(), "Not Connected", Toast.LENGTH_SHORT).show();
                }
            });
        }
    });
}

private void initialWork() {
    btnDiscover = (Button) findViewById(R.id.discover);
    btnOnOff = (Button) findViewById(R.id.onOff);
    btnSend = (Button) findViewById(R.id.sendButton);
    listView = (ListView) findViewById(R.id.peerListView);
    read_msg_box = (TextView) findViewById(R.id.readmsg);
    connectionStatus = (TextView) findViewById(R.id.connectionStatus);
    writeMsg = (EditText) findViewById(R.id.writeMsg);

    wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);

    mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
    mChannel = mManager.initialize(this, getMainLooper(),null);

    mReceiver = new WifiDirectBroadcastReceiver(mManager, mChannel, this);
    mIntentFilter = new IntentFilter();
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
    mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
}
WifiP2pManager.PeerListListener peerListListener = new WifiP2pManager.PeerListListener() {
    @Override
    public void onPeersAvailable(WifiP2pDeviceList peerList) {
        if(!peerList.getDeviceList().equals(peers)){
            peers.clear();
            peers.addAll(peerList.getDeviceList());
            deviceNameArray = new String[peerList.getDeviceList().size()];
            deviceArray = new WifiP2pDevice[peerList.getDeviceList().size()];
            int index = 0;
            for(WifiP2pDevice device : peerList.getDeviceList()){
                deviceNameArray[index] = device.deviceName;
                deviceArray[index] = device;
                index++;
            }
            ArrayAdapter <String> adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, deviceNameArray);
            listView.setAdapter(adapter);
        }
        if (peers.size() == 0){
            Toast.makeText(getApplicationContext(), "No Device Found",Toast.LENGTH_SHORT).show();
            return;
        }
    }
};

WifiP2pManager.ConnectionInfoListener connectionInfoListener = new WifiP2pManager.ConnectionInfoListener() {
    @Override
    public void onConnectionInfoAvailable(WifiP2pInfo wifiP2pInfo) {
        final InetAddress groupOwnerAddress = wifiP2pInfo.groupOwnerAddress;
        if(wifiP2pInfo.groupFormed && wifiP2pInfo.isGroupOwner){
            connectionStatus.setText("Host");
        }
        else if (wifiP2pInfo.groupFormed){
            connectionStatus.setText("Client");
        }
    }
};

@Override
protected void onResume() {
    super.onResume();
    registerReceiver(mReceiver, mIntentFilter);
}

@Override
protected void onPause() {
    super.onPause();
    unregisterReceiver(mReceiver);
}

public class ServerClass extends AsyncTask<String, Integer, Boolean> {
    Socket socket;
    ServerSocket serverSocket;
    InputStream inputStream;
    OutputStream outputStream;
    @Override
    protected Boolean doInBackground(String... strings) {
        boolean result = true;
        try {
            serverSocket = new ServerSocket(8888);
            socket = serverSocket.accept();
        } catch (IOException e) {
            result = false;
            e.printStackTrace();
        }
        return result;
    }
    public void writeData(final byte[] bytes) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    outputStream.write(bytes);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        btnSend.setVisibility(View.VISIBLE);
    }

    @Override
    protected void onPostExecute(Boolean result) {
        if(result) {
            try {
                inputStream = socket.getInputStream();
                outputStream = socket.getOutputStream();
            } catch (IOException e) {
                e.printStackTrace();
            }
            new Thread(new Runnable(){
                public void run() {
                    byte[] buffer = new byte[1024];
                    int x;
                    while (socket!=null) {
                        try {
                            x = inputStream.read(buffer);
                            if(x>0) {
                                handler.obtainMessage(MESSAGE_READ,x,-1,buffer).sendToTarget();
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }).start();
            btnSend.setVisibility(View.VISIBLE);
        } else {
            Toast.makeText(getApplicationContext(),"could not create sockets",Toast.LENGTH_SHORT).show();
            //restart socket assignment process
        }
    }
}

private class SendReceive extends  Thread{
    private Socket socket;
    private InputStream inputStream;
    private OutputStream outputStream;

    public SendReceive(Socket skt){
        socket = skt;
        try {
            inputStream = socket.getInputStream();
            outputStream = socket.getOutputStream();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        byte[] buffer = new byte[1024];
        int bytes;
        while (socket != null){
            try {
                bytes = inputStream.read(buffer);
                if (bytes > 0){
                    handler.obtainMessage(MESSAGE_READ,bytes,-1,buffer).sendToTarget();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    public  void write(byte[] bytes){
        try {
            outputStream.write(bytes);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class ClientClass extends AsyncTask<String, Integer, Boolean>{
    Socket socket;
    String hostAdd;
    InputStream inputStream;
    OutputStream outputStream;

    public ClientClass(InetAddress hostAddress) {
        hostAdd = hostAddress.getHostAddress();
        socket = new Socket();
    }
    @Override
    protected Boolean doInBackground(String... strings) {
        boolean result = false;
        try {
            socket.connect(new InetSocketAddress(hostAdd, 8888), 5000);
            result = true;
            return result;
        } catch (IOException e) {
            e.printStackTrace();
            result = false;
            return result;
        }
    }
    public void writeData(final byte[] bytes) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    outputStream.write(bytes);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }).start();
        btnSend.setVisibility(View.VISIBLE);
    }

    @Override
    protected void onPostExecute(Boolean result) {
        if(result) {
            try {
                inputStream = socket.getInputStream();
                outputStream = socket.getOutputStream();
            } catch (IOException e) {
                e.printStackTrace();
            }
            new Thread(new Runnable(){
                public void run() {
                    byte[] buffer = new byte[1024];
                    int x;
                    while (socket!=null) {
                        try {
                            x = inputStream.read(buffer);
                            if(x>0) {
                                handler.obtainMessage(MESSAGE_READ,x,-1,buffer).sendToTarget();
                            }
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }).start();
            btnSend.setVisibility(View.VISIBLE);
        } else {
            Toast.makeText(getApplicationContext(),"could not create sockets",Toast.LENGTH_SHORT).show();
        }
    }
}
}

和xml文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"enter code here
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical">

<Button
    android:id="@+id/onOff"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginStart="25dp"
    android:layout_marginTop="55dp"
    android:text="Wifi On"/>

<Button
    android:id="@+id/discover"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/onOff"
    android:layout_alignBottom="@+id/onOff"
    android:layout_centerHorizontal="true"
    android:text="Discover" />

<ListView
    android:id="@+id/peerListView"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:layout_alignParentStart="true"
    android:layout_below="@+id/onOff"
    android:layout_marginTop="25dp"
    android:background="@android:color/holo_blue_light">
</ListView>

<TextView
    android:id="@+id/readmsg"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentEnd="true"
    android:layout_below="@+id/peerListView"
    android:layout_marginTop="31dp"
    android:text="Message"
    android:textAlignment="center"
    android:textSize="20dp"
    android:textStyle="italic"/>

<EditText
    android:id="@+id/writeMsg"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentBottom="true"
    android:ems="10"
    android:inputType="textPersonName"
    android:layout_toStartOf="@id/sendButton"/>

<Button
    android:id="@+id/sendButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:text="SEND"/>

<TextView
    android:id="@+id/connectionStatus"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="15dp"
    android:textAlignment="center"
    android:text="Connection Status"
    android:textColor="@color/design_default_color_primary_dark"
    android:textSize="15dp"
    android:textStyle="italic"/>

</RelativeLayout>

---

按下发送按钮后，应该发送消息，但它会使整个应用程序崩溃。请提供帮助。

在此处输入代码

请提供完整的问题。先生，我提供的上述代码是通过Wi-Fi direct p2p连接和共享短信。整个应用程序运行得非常完美，即打开/关闭Wifi，并使用设备进行查找和窥视，但当我向其他设备发送消息时，或者当我只是单击“发送”按钮时，应用程序崩溃。是的，我们从问题中的描述中了解到了这一点。我要求的，所以我们可以确定原因。但是，我要提到的是，您从未分配过

serverClass

或

clientClass

，因此当您单击发送

按钮时，这些值为空。
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"enter code here
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical">

<Button
    android:id="@+id/onOff"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginStart="25dp"
    android:layout_marginTop="55dp"
    android:text="Wifi On"/>

<Button
    android:id="@+id/discover"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignBaseline="@+id/onOff"
    android:layout_alignBottom="@+id/onOff"
    android:layout_centerHorizontal="true"
    android:text="Discover" />

<ListView
    android:id="@+id/peerListView"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:layout_alignParentStart="true"
    android:layout_below="@+id/onOff"
    android:layout_marginTop="25dp"
    android:background="@android:color/holo_blue_light">
</ListView>

<TextView
    android:id="@+id/readmsg"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentEnd="true"
    android:layout_below="@+id/peerListView"
    android:layout_marginTop="31dp"
    android:text="Message"
    android:textAlignment="center"
    android:textSize="20dp"
    android:textStyle="italic"/>

<EditText
    android:id="@+id/writeMsg"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentBottom="true"
    android:ems="10"
    android:inputType="textPersonName"
    android:layout_toStartOf="@id/sendButton"/>

<Button
    android:id="@+id/sendButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentEnd="true"
    android:text="SEND"/>

<TextView
    android:id="@+id/connectionStatus"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="15dp"
    android:textAlignment="center"
    android:text="Connection Status"
    android:textColor="@color/design_default_color_primary_dark"
    android:textSize="15dp"
    android:textStyle="italic"/>

</RelativeLayout>