如何将 BLE 设备在片段中发送的数据发送到新的活动以在应用程序中显示和绘制图形？

Question

I am completely new to Android and just learned Object-oriented programming. My project requires me to build something on open-source code. I am really struggling with this special case. Two fragments are under activity_main, one of them is TerminalFragment. I added a menuItem (R.id.plot) in it and set if the user clicks this Item that will lead him from TerminalFragment to activity_main2. Due to receive(byte data) and TerminalFragment still on active, the data is still printing out by receiveText.append(TextUtil.toCaretString(msg, newline.length() != 0));in activity_main.

Now, I want to convert the data to String and send it to activity_main2 for display in recyclerview and plotting graph. I am trying to use putextra and getextra but not sure how to access data from getextra in activity_main2. In my testing, the recyclerview just showed "John". Is something missing in my method? Does anyone have a better idea? Much Appreciated.

TerminalFragment

package de.kai_morich.simple_bluetooth_le_terminal;

import android.app.Activity;
import android.app.AlertDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.text.Editable;
import android.text.Spannable;
import android.text.SpannableStringBuilder;
import android.text.method.ScrollingMovementMethod;
import android.text.style.ForegroundColorSpan;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import androidx.appcompat.app.AppCompatActivity;
import android.widget.EditText;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;

public class TerminalFragment extends Fragment implements ServiceConnection, SerialListener {

    private MenuItem menuItem;
    private enum Connected { False, Pending, True }

    private String deviceAddress;
    private SerialService service;

    private TextView receiveText;
    private TextView sendText;
    private TextUtil.HexWatcher hexWatcher;

    private Connected connected = Connected.False;
    private boolean initialStart = true;
    private boolean hexEnabled = false;
    private boolean pendingNewline = false;
    private String newline = TextUtil.newline_crlf;
    private String output;

    /*
     * Lifecycle
     */
    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setHasOptionsMenu(true);
        //Register with activity
        // You must inform the system that your app bar fragment is participating in the population of the options menu.
        // tells the system that your fragment would like to receive menu-related callbacks.

        setRetainInstance(true);
        deviceAddress = getArguments().getString("device");
    }

    @Override
    public void onDestroy() {
        if (connected != Connected.False)
            disconnect();
        getActivity().stopService(new Intent(getActivity(), SerialService.class));
        super.onDestroy();
    }

    @Override
    public void onStart() {
        super.onStart();
        if(service != null)
            service.attach(this);
        else
            getActivity().startService(new Intent(getActivity(), SerialService.class)); // prevents service destroy on unbind from recreated activity caused by orientation change
    }

    @Override
    public void onStop() {
        if(service != null && !getActivity().isChangingConfigurations())
            service.detach();
        super.onStop();
    }

    @SuppressWarnings("deprecation") // onAttach(context) was added with API 23. onAttach(activity) works for all API versions
    @Override
    public void onAttach(@NonNull Activity activity) {
        super.onAttach(activity);
        getActivity().bindService(new Intent(getActivity(), SerialService.class), this, Context.BIND_AUTO_CREATE);
    }

    @Override
    public void onDetach() {
        try { getActivity().unbindService(this); } catch(Exception ignored) {}
        super.onDetach();
    }

    @Override
    public void onResume() {
        super.onResume();
        if(initialStart && service != null) {
            initialStart = false;
            getActivity().runOnUiThread(this::connect);
        }
    }

    @Override
    public void onServiceConnected(ComponentName name, IBinder binder) {
        service = ((SerialService.SerialBinder) binder).getService();
        service.attach(this);
        if(initialStart && isResumed()) {
            initialStart = false;
            getActivity().runOnUiThread(this::connect);
        }
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
        service = null;
    }

    /*
     * UI
     */
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_terminal, container, false);
        receiveText = view.findViewById(R.id.receive_text);                          // TextView performance decreases with number of spans
        receiveText.setTextColor(getResources().getColor(R.color.colorRecieveText)); // set as default color to reduce number of spans
        receiveText.setMovementMethod(ScrollingMovementMethod.getInstance());

        sendText = view.findViewById(R.id.send_text);
        hexWatcher = new TextUtil.HexWatcher(sendText);
        hexWatcher.enable(hexEnabled);
        sendText.addTextChangedListener(hexWatcher);
        sendText.setHint(hexEnabled ? "HEX mode" : "");

        View sendBtn = view.findViewById(R.id.send_btn);
        sendBtn.setOnClickListener(v -> send(sendText.getText().toString()));
        return view;
    }

    @Override
    public void onCreateOptionsMenu(@NonNull Menu menu, MenuInflater inflater) {
        inflater.inflate(R.menu.menu_terminal, menu);
        menu.findItem(R.id.hex).setChecked(hexEnabled);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.clear) {
            receiveText.setText("");
            return true;
        } if (id == R.id.plot){
            Intent intent = new Intent(getActivity(), MainActivity2.class);
            startActivity(intent);
            //receive.;
            return true;
        }else if (id == R.id.newline) {
            String[] newlineNames = getResources().getStringArray(R.array.newline_names);
            String[] newlineValues = getResources().getStringArray(R.array.newline_values);
            int pos = java.util.Arrays.asList(newlineValues).indexOf(newline);
            AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
            builder.setTitle("Newline");
            builder.setSingleChoiceItems(newlineNames, pos, (dialog, item1) -> {
                newline = newlineValues[item1];
                dialog.dismiss();
            });
            builder.create().show();
            return true;
        } else if (id == R.id.hex) {
            hexEnabled = !hexEnabled;
            sendText.setText("");
            hexWatcher.enable(hexEnabled);
            sendText.setHint(hexEnabled ? "HEX mode" : "");
            item.setChecked(hexEnabled);
            return true;
        } else {
            return super.onOptionsItemSelected(item);
        }
    }

    /*
     * Serial + UI
     */
    private void connect() {
        try {
            BluetoothAdapter bluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
            BluetoothDevice device = bluetoothAdapter.getRemoteDevice(deviceAddress);
            status("connecting...");
            connected = Connected.Pending;
            SerialSocket socket = new SerialSocket(getActivity().getApplicationContext(), device);
            service.connect(socket);
        } catch (Exception e) {
            onSerialConnectError(e);
        }
    }

    private void disconnect() {
        connected = Connected.False;
        service.disconnect();
    }

    private void send(String str) {
        if(connected != Connected.True) {
            Toast.makeText(getActivity(), "not connected", Toast.LENGTH_SHORT).show();
            return;
        }
        try {
            String msg;
            byte[] data;
            if(hexEnabled) {
                StringBuilder sb = new StringBuilder();
                TextUtil.toHexString(sb, TextUtil.fromHexString(str));
                TextUtil.toHexString(sb, newline.getBytes());
                msg = sb.toString();
                data = TextUtil.fromHexString(msg);
            } else {
                msg = str;
                data = (str + newline).getBytes();
            }
            SpannableStringBuilder spn = new SpannableStringBuilder(msg + '\n');
            spn.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.colorSendText)), 0, spn.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
            receiveText.append(spn);
            service.write(data);
        } catch (Exception e) {
            onSerialIoError(e);
        }
    }

    private void receive(byte[] data) {
        if(hexEnabled) {
            receiveText.append("Hello" + TextUtil.toHexString(data) + '\n');
        } else {
            String msg = new String(data);
            if(newline.equals(TextUtil.newline_crlf) && msg.length() > 0) {
                // don't show CR as ^M if directly before LF
                msg = msg.replace(TextUtil.newline_crlf, TextUtil.newline_lf);
                // special handling if CR and LF come in separate fragments
                if (pendingNewline && msg.charAt(0) == '\n') {
                    Editable edt = receiveText.getEditableText();
                    if (edt != null && edt.length() > 1)
                        edt.replace(edt.length() - 2, edt.length(), "");
                }
                pendingNewline = msg.charAt(msg.length() - 1) == '\r';
            }
            receiveText.append(TextUtil.toCaretString(msg, newline.length() != 0)); //print out data
            output = receiveText.toString(); // CharSequence to String
            Intent intent = new Intent(getActivity(), MainActivity2.class);
            intent.putExtra("output",output); // send data to next activity, MainActivity2
        }
    }

    private void status(String str) {
        SpannableStringBuilder spn = new SpannableStringBuilder(str + '\n');
        spn.setSpan(new ForegroundColorSpan(getResources().getColor(R.color.colorStatusText)), 0, spn.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        receiveText.append(spn);
    }

    /*
     * SerialListener
     */
    @Override
    public void onSerialConnect() {
        status("connected");
        connected = Connected.True;
    }

    @Override
    public void onSerialConnectError(Exception e) {
        status("connection failed: " + e.getMessage());
        disconnect();
    }

    @Override
    public void onSerialRead(byte[] data) {// receive data
        receive(data); // send data to printout
    }

    @Override
    public void onSerialIoError(Exception e) {
        status("connection lost: " + e.getMessage());
        disconnect();
    }

}

MainActivity2.java (new activity)

package de.kai_morich.simple_bluetooth_le_terminal;

import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;
import androidx.recyclerview.widget.DefaultItemAnimator;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity2 extends AppCompatActivity {

    Fragment CustomFragment;
    private ArrayList<Data> dataList;
    private RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        Toolbar toolbar = findViewById(R.id.toolbar2);
        setSupportActionBar(toolbar);
        recyclerView = findViewById(R.id.dataflow);
        dataList = new ArrayList<>();
        String data;
        if (savedInstanceState == null) {
            Bundle extra = getIntent().getExtras();
            if (extra == null) {
                data = null;
                receiveData(data);
            } else {
                data = extra.getString("output");
                receiveData(data);
            }
        } else {
            data = (String) savedInstanceState.getSerializable("output");
            receiveData(data);
        }
        setAdapter();
    }

    private void receiveData(String data){
        String Data = data;
        dataList.add(new Data("John"));
        dataList.add(new Data(Data));
    }

    private void setAdapter() {
        recyclerAdapter adapter = new recyclerAdapter(dataList);
        RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(adapter);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.menu_plot, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.dataplot:
                Toast.makeText(this, "dataplot", Toast.LENGTH_SHORT).show();
                replaceFragment(new DataPlotFragment());
                return true;
            case R.id.fft:
                Toast.makeText(this, "FFT", Toast.LENGTH_SHORT).show();
                replaceFragment(new FftFragment());
                return true;
            case R.id.data:
                Toast.makeText(this, "DATA", Toast.LENGTH_SHORT).show();
                finish();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }
    private void replaceFragment(Fragment fragment){

        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.plotframelayout,fragment);
        fragmentTransaction.commit();
    }


}

Answer 1

I realized I also need to add getText() in receive(). However, the recycler view won't update itself, it just captures what it has in the recyclerview of activity_main with TerminalFragment when the user click the menuItem (id,plot). Either getextrastring() or using bundle able to pass the data to Mainactivity2. I think I need to add something else to keep adding data to the recyclerview of activity_main2 from activity_main.

onOptionsItemSelected of TerminalFragment

if (id == R.id.plot){
            Intent intent = new Intent(getActivity(), MainActivity2.class);
            intent.putExtra("output",output); //output
            startActivity(intent);
            return true;
        }

receive() of TerminalFragment

private void receive(byte[] data) {
        if(hexEnabled) {
            receiveText.append("Hello" + TextUtil.toHexString(data) + '\n');
        } else {
            String msg = new String(data);
            if(newline.equals(TextUtil.newline_crlf) && msg.length() > 0) {
                // don't show CR as ^M if directly before LF
                msg = msg.replace(TextUtil.newline_crlf, TextUtil.newline_lf);
                // special handling if CR and LF come in separate fragments
                if (pendingNewline && msg.charAt(0) == '\n') {
                    Editable edt = receiveText.getEditableText();
                    if (edt != null && edt.length() > 1)
                        edt.replace(edt.length() - 2, edt.length(), "");
                }
                pendingNewline = msg.charAt(msg.length() - 1) == '\r';
            }
            receiveText.append(TextUtil.toCaretString(msg, newline.length() != 0)); //print out data
            output = receiveText.getText().toString(); // CharSequence to String
        }
    }

OnCreate of mainActivity2

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        Toolbar toolbar = findViewById(R.id.toolbar2);
        setSupportActionBar(toolbar);
        recyclerView = findViewById(R.id.dataflow);
        dataList = new ArrayList<>();
        String data;
        Bundle extras = getIntent().getExtras();
        if (extras != null)
        {
            data = extras.getString("output");
            receiveData(data);
        }
        setAdapter();
    }