从 textview 获取值

Question

Hello guys I got a code that I do for my project, the code is to get the value of the heartbeat sensor from Arduino to my android phone using Bluetooth. So far it's going well it can send the value to my app without a problem. but the problem now is I want to get the value of it so I can use my algorithm with it, but seems like I got in a pickle now.

Here is the code :

package com.test.aplikasirevisi;

import java.io.IOException;
import java.io.InputStream;
import java.util.UUID;
import android.app.Activity;
import android.app.ProgressDialog;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.ScrollView;
import android.widget.TextView;
import android.widget.Toast;

public class MonitoringScreen extends Activity {
    private static final String TAG = "BlueTest5-MainActivity";
    private int mMaxChars = 50000;//Default
    private UUID mDeviceUUID;
    private BluetoothSocket mBTSocket;
    private ReadInput mReadThread = null;

    private boolean mIsUserInitiatedDisconnect = false;

    private TextView mTxtReceive;
    private Button mBtnClearInput;
    private ScrollView scrollView;
    private CheckBox chkScroll;
    private CheckBox chkReceiveText;


    private boolean mIsBluetoothConnected = false;

    private BluetoothDevice mDevice;

    private ProgressDialog progressDialog;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_monitoring_screen);
        ActivityHelper.initialize(this);

        Intent intent = getIntent();
        Bundle b = intent.getExtras();
        mDevice = b.getParcelable(MainActivity.DEVICE_EXTRA);
        mDeviceUUID = UUID.fromString(b.getString(MainActivity.DEVICE_UUID));
        mMaxChars = b.getInt(MainActivity.BUFFER_SIZE);
        Log.d(TAG, "Ready");
        mTxtReceive = (TextView) findViewById(R.id.txtReceive);
        chkScroll = (CheckBox) findViewById(R.id.chkScroll);
        chkReceiveText = (CheckBox) findViewById(R.id.chkReceiveText);
        scrollView = (ScrollView) findViewById(R.id.viewScroll);
        mBtnClearInput = (Button) findViewById(R.id.btnClearInput);
        mTxtReceive.setMovementMethod(new ScrollingMovementMethod());






        mBtnClearInput.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                mTxtReceive.setText("");
            }
        });
    }
    private class ReadInput implements  Runnable{
        private boolean bStop = false;
        private Thread t;

        public ReadInput() {
            t = new Thread(this, "Input Thread");
            t.start();
        }

        public boolean isRunning() {
            return t.isAlive();
        }

        @Override
        public void run() {
            InputStream inputStream;

            try {
                inputStream = mBTSocket.getInputStream();
                while (!bStop) {
                    byte[] buffer = new byte[256];
                    if (inputStream.available() > 0) {
                        inputStream.read(buffer);
                        int i;
                        /*
                         * This is needed because new String(buffer) is taking the entire buffer i.e. 256 chars on Android 2.3.4 http://stackoverflow.com/a/8843462/1287554
                         */
                        for (i = 0; i < buffer.length && buffer[i] != 0; i++) {
                        }
                        final String strInput = new String(buffer, 0, i);

                        /*
                         * If checked then receive text, better design would probably be to stop thread if unchecked and free resources, but this is a quick fix
                         */

                        if (chkReceiveText.isChecked()) {
                            mTxtReceive.post(new Runnable() {
                                @Override
                                public void run() {
                                    mTxtReceive.append(strInput);

                                    int txtLength = mTxtReceive.getEditableText().length();
                                    if(txtLength > mMaxChars){
                                        mTxtReceive.getEditableText().delete(0, txtLength - mMaxChars);
                                        System.out.println(mTxtReceive.getText().toString());
                                    }

                                    if (chkScroll.isChecked()) { // Scroll only if this is checked
                                        scrollView.post(new Runnable() { // Snippet from http://stackoverflow.com/a/4612082/1287554
                                            @Override
                                            public void run() {
                                                scrollView.fullScroll(View.FOCUS_DOWN);
                                            }
                                        });
                                    }
                                }
                            });
                        }

                    }
                    Thread.sleep(500);
                }
            } catch (IOException e) {
// TODO Auto-generated catch block
                e.printStackTrace();
            } catch (InterruptedException e) {
// TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        public void stop() {
            bStop = true;
        }

    }
    private class DisConnectBT extends AsyncTask<Void, Void, Void> {

        @Override
        protected void onPreExecute() {
        }

        @Override
        protected Void doInBackground(Void... params) {

            if (mReadThread != null) {
                mReadThread.stop();
                while (mReadThread.isRunning())
                    ; // Wait until it stops
                mReadThread = null;

            }

            try {
                mBTSocket.close();
            } catch (IOException e) {
// TODO Auto-generated catch block
                e.printStackTrace();
            }

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            mIsBluetoothConnected = false;
            if (mIsUserInitiatedDisconnect) {
                finish();
            }
        }

    }
    private void msg(String s) {
        Toast.makeText(getApplicationContext(), s, Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onPause() {
        if (mBTSocket != null && mIsBluetoothConnected) {
            new DisConnectBT().execute();
        }
        Log.d(TAG, "Paused");
        super.onPause();
    }

    @Override
    protected void onResume() {
        if (mBTSocket == null || !mIsBluetoothConnected) {
            new ConnectBT().execute();
        }
        Log.d(TAG, "Resumed");
        super.onResume();
    }

    @Override
    protected void onStop() {
        Log.d(TAG, "Stopped");
        super.onStop();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
// TODO Auto-generated method stub
        super.onSaveInstanceState(outState);
    }

    private class ConnectBT extends AsyncTask<Void, Void, Void> {
        private boolean mConnectSuccessful = true;

        @Override
        protected void onPreExecute() {
            progressDialog = ProgressDialog.show(MonitoringScreen.this, "Hold on", "Connecting");// http://stackoverflow.com/a/11130220/1287554
        }

        @Override
        protected Void doInBackground(Void... devices) {

            try {
                if (mBTSocket == null || !mIsBluetoothConnected) {
                    mBTSocket = mDevice.createInsecureRfcommSocketToServiceRecord(mDeviceUUID);
                    BluetoothAdapter.getDefaultAdapter().cancelDiscovery();
                    mBTSocket.connect();
                }
            } catch (IOException e) {
// Unable to connect to device
                e.printStackTrace();
                mConnectSuccessful = false;
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);

            if (!mConnectSuccessful) {
                Toast.makeText(getApplicationContext(), "Could not connect to device. Is it a Serial device? Also check if the UUID is correct in the settings", Toast.LENGTH_LONG).show();
                finish();
            } else {
                msg("Connected to device");
                mIsBluetoothConnected = true;
                mReadThread = new ReadInput(); // Kick off input reader
            }

            progressDialog.dismiss();
        }

    }
}

What i want is to get the value of mTxtReceive on this :

int txtLength = mTxtReceive.getEditableText().length();
                                    if(txtLength > mMaxChars){
                                        mTxtReceive.getEditableText().delete(0, txtLength - mMaxChars);
                                        System.out.println(mTxtReceive.getText().toString());
                                    }

I used System.out.println for seeing if i got the value but in the log it didn't show any thing. So i need you guys wisdom for this any help?

Answer 1

Your view mTextReceive seems to be a TextView and therefore not editable:

private TextView mTxtReceive;

If it's not an EditText (editable) mTxtReceive.getEditableText will return null see docs and getText should be called instead see docs .

Therefore your condition might always resolve from if(txtLength > mMaxChars) into if(null > 50000) which is always false (or actually it might even crash before) and therefore your code inside the if-block is never executed

Try:

// recommended for debugging. Check if this is even called and if text length is really longer than max chars
Log.d(TAG, "text length:" + mTxtReceive.getText().length()); 
int txtLength = mTxtReceive.getText().length();
if(txtLength > mMaxChars){
  // not sure what operation you want to do here but leave out for debugging                                
  Log.d(TAG, "text longer than allowed:" + mTxtReceive.getText().toString());
}

Also use Log.d instead of System.out.println since your log might otherwise not be forwarded to Logcat. Also are you sure this block is executed at all? I'd put a Log.d(TAG, "text length:" + mTxtReceive.getText().length()); outside of the condition for debugging purposes. And finally the obvious question would be if the txtLength is even longer than max chars (and that would be quite a long text with 50000 chars). But you can verify that simply with the recommended log outside the block as well.