【解決方法】Bluetooth使用時のアプリクラッシュ問題の解決方法(android studio)

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Bluetooth接続を使用してESP32から測定値を読み取る必要があるアプリ(端末)を作成する必要があるプロジェクトがあります。私はなんとか端末を構築し、いくつかの機能を備えたボタンを追加しました。問題は、[List devices]ボタンをクリックすると、使用可能なすべての Bluetooth デバイスが一覧表示され、ESP32 デバイスをクリックして接続するとクラッシュすることです。マニフェストにすべての権限がありますが、まだこの問題があります。

Java

package com.example.plavi_zub_2;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;

import android.Manifest;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;

public class MainActivity extends AppCompatActivity {

    Button listen, send, listDevices;
    ListView listView;
    TextView msg_box, status;
    EditText writeMsg;

    BluetoothAdapter bluetoothAdapter;
    BluetoothDevice[] btArray;

    SendReceive sendReceive;

    static final int STATE_LISTENING = 1;
    static final int STATE_CONNECTING = 2;
    static final int STATE_CONNECTED = 3;
    static final int STATE_CONNECTION_FAILED = 4;
    static final int STATE_MESSAGE_RECEIVED = 5;

    int REQUEST_ENABLE_BLUETOOTH = 1;

    private static final String APP_NAME = "BTChat";
    private static final UUID MY_UUID = UUID.fromString("8ce255c0-223a-11e0-ac64-0803450c9a66");

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

        findViewByIdes();
        bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

        if (!bluetoothAdapter.isEnabled()) {
            Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED) {
                startActivityForResult(enableIntent, REQUEST_ENABLE_BLUETOOTH);
                // TODO: Consider calling
                //    ActivityCompat#requestPermissions
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for ActivityCompat#requestPermissions for more details.
                return;
            } else {
                ActivityCompat.requestPermissions(MainActivity.this, new String[]{android.Manifest.permission.BLUETOOTH_CONNECT}, 44);
            }

        }

        implementListeners();

    }

    private void implementListeners() {

        listDevices.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if (ActivityCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED) {
                    Set<BluetoothDevice> bt = bluetoothAdapter.getBondedDevices();
                    String[] strings = new String[bt.size()];
                    btArray = new BluetoothDevice[bt.size()];
                    int index = 0;

                    if (bt.size() > 0) {
                        for (BluetoothDevice device : bt) {
                            btArray[index] = device;
                            strings[index] = device.getName();
                            index++;
                        }
                        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, strings);
                        listView.setAdapter(arrayAdapter);
                    }
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                } else {
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.BLUETOOTH_CONNECT}, 44);
                }
            }


//                String[] strings = new String[bt.size()];
//                btArray = new BluetoothDevice[bt.size()];
//                int index = 0;
//
//                if (bt.size() > 0) {
//                    for (BluetoothDevice device : bt) {
//                        btArray[index] = device;
//                        strings[index] = device.getName();
//                        index++;
//                    }
//                    ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, strings);
//                    listView.setAdapter(arrayAdapter);
//                }
//            }
        });

        listen.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                ServerClass serverClass = new ServerClass();
                serverClass.start();
            }
        });

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
                ClientClass clientClass = new ClientClass(btArray[i]);
                clientClass.start();

                status.setText("Connecting");
            }
        });

        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String string = String.valueOf(writeMsg.getText());
                sendReceive.write(string.getBytes());
            }
        });

    }

    Handler handler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message msg) {

            switch (msg.what) {
                case STATE_LISTENING:
                    status.setText("Listening");
                    break;
                case STATE_CONNECTING:
                    status.setText("Connecting");
                    break;
                case STATE_CONNECTED:
                    status.setText("Connected");
                    break;
                case STATE_CONNECTION_FAILED:
                    status.setText("Connection Failed");
                    break;
                case STATE_MESSAGE_RECEIVED:
                    byte[] readBuff = (byte[]) msg.obj;
                    String tempMsg = new String(readBuff, 0, msg.arg1);
                    msg_box.setText(tempMsg);
                    break;
            }
            return true;
        }
    });

    private void findViewByIdes() {
        listen = (Button) findViewById(R.id.listen);
        send = (Button) findViewById(R.id.send);
        listView = (ListView) findViewById(R.id.listview);
        msg_box = (TextView) findViewById(R.id.msg);
        status = (TextView) findViewById(R.id.status);
        writeMsg = (EditText) findViewById(R.id.writemsg);
        listDevices = (Button) findViewById(R.id.listDevices);
    }

    private class ServerClass extends Thread {
        private BluetoothServerSocket serverSocket;

        public ServerClass() {
            try {
                if (ActivityCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.BLUETOOTH_CONNECT) == PackageManager.PERMISSION_GRANTED) {
                    serverSocket = bluetoothAdapter.listenUsingRfcommWithServiceRecord(APP_NAME, MY_UUID);
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                } else
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.BLUETOOTH_CONNECT}, 44);
                //serverSocket = bluetoothAdapter.listenUsingRfcommWithServiceRecord(APP_NAME, MY_UUID);
                // serverSocket = bluetoothAdapter.listenUsingRfcommWithServiceRecord(APP_NAME, MY_UUID);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void run() {
            BluetoothSocket socket = null;

            while (socket == null) {
                try {
                    Message message = Message.obtain();
                    message.what = STATE_CONNECTING;
                    handler.sendMessage(message);

                    socket = serverSocket.accept();
                } catch (IOException e) {
                    e.printStackTrace();
                    Message message = Message.obtain();
                    message.what = STATE_CONNECTION_FAILED;
                    handler.sendMessage(message);
                }

                if (socket != null) {
                    Message message = Message.obtain();
                    message.what = STATE_CONNECTED;
                    handler.sendMessage(message);

                    sendReceive = new SendReceive(socket);
                    sendReceive.start();

                    break;
                }
            }
        }
    }

    private class ClientClass extends Thread {
        private BluetoothDevice device;
        private BluetoothSocket socket;

        public ClientClass(BluetoothDevice device1) {
            device = device1;

            try {
                if (ActivityCompat.checkSelfPermission(MainActivity.this, android.Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
                    socket = device.createInsecureRfcommSocketToServiceRecord(MY_UUID);
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                } else
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.BLUETOOTH_CONNECT}, 44);
                //socket = device.createInsecureRfcommSocketToServiceRecord(MY_UUID);

            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        public void run() {
            try {

                if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.BLUETOOTH_CONNECT) != PackageManager.PERMISSION_GRANTED) {
                    socket.connect();
                    Message message=Message.obtain();
                    message.what=STATE_CONNECTED;
                    handler.sendMessage(message);

                    sendReceive=new SendReceive(socket);
                    sendReceive.start();
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                }else
                    ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.BLUETOOTH_CONNECT}, 44);

                //socket.connect();
//                Message message=Message.obtain();
//                message.what=STATE_CONNECTED;
//                handler.sendMessage(message);

                sendReceive=new SendReceive(socket);
                sendReceive.start();

            } catch (IOException e) {
                e.printStackTrace();
                Message message=Message.obtain();
                message.what=STATE_CONNECTION_FAILED;
                handler.sendMessage(message);
            }
        }
    }
    private class SendReceive extends Thread
    {
        private final BluetoothSocket bluetoothSocket;
        private final InputStream inputStream;
        private final OutputStream outputStream;

        public SendReceive (BluetoothSocket socket)
        {
            bluetoothSocket=socket;
            InputStream tempIn=null;
            OutputStream tempOut=null;

            try {
                tempIn=bluetoothSocket.getInputStream();
                tempOut=bluetoothSocket.getOutputStream();
            } catch (IOException e) {
                e.printStackTrace();
            }

            inputStream=tempIn;
            outputStream=tempOut;
        }

        public void run()
        {
            byte[] buffer=new byte[1024];
            int bytes;

            while (true)
            {
                try {
                    bytes=inputStream.read(buffer);
                    handler.obtainMessage(STATE_MESSAGE_RECEIVED,bytes,-1,buffer).sendToTarget();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

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


}

そして、次のようなエラーがいくつかあります。

Java

Unable to open libpenguin.so: dlopen failed: library "libpenguin.so" not found.

Java

FATAL EXCEPTION: Thread-3
                                                                                                    Process: com.example.plavi_zub_2, PID: 18858
                                                                                                    java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.InputStream android.bluetooth.BluetoothSocket.getInputStream()' on a null object reference
                                                                                                    	at com.example.plavi_zub_2.MainActivity$SendReceive.<init>(MainActivity.java:331)
                                                                                                    	at com.example.plavi_zub_2.MainActivity$ClientClass.run(MainActivity.java:307)

私が試したこと：

公式の Android dev サイトで解決策を見つけようとしましたが、問題は解決しませんでした。

解決策 1

エラーメッセージによると、次の 2 つの明らかな問題があります。
1. penguin コードを実行しようとすると、ライブラリがシステムに存在しないか、システムに見つかりません。それがどこにあるかを調べるか、インストールする必要があります。
2. 他のエラーメッセージの行番号の前後のコードを調べます。 null オブジェクトでメソッドを呼び出しています。これは、使用している参照が初期化されていないことを意味します。

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