从 textview 获取值

Question

大家好，我为我的项目编写了一个代码，该代码是使用蓝牙将心跳传感器的值从 Arduino 获取到我的 android 手机。 到目前为止一切顺利，它可以毫无问题地将值发送到我的应用程序。 但现在的问题是我想获得它的价值，以便我可以使用我的算法，但现在似乎我陷入了困境。

这是代码：

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();
        }

    }
}

我想要的是获得 mTxtReceive 的价值：

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

我使用 System.out.println 来查看我是否得到了值，但在日志中它没有显示任何内容。 所以我需要你们的智慧对此有什么帮助吗？

Answer 1

您的视图mTextReceive似乎是一个TextView ，因此不可编辑：

private TextView mTxtReceive;

如果它不是EditText （可编辑），则mTxtReceive.getEditableText将返回null 请参阅 docs并且应该调用getText而不是see docs 。

因此，您的条件可能总是从if(txtLength > mMaxChars)解析为if(null > 50000)始终为false （或者实际上它甚至可能之前崩溃），因此您在 if 块中的代码永远不会执行

尝试：

// 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());
}

还要使用Log.d而不是System.out.println因为否则您的日志可能不会转发到 Logcat。 另外你确定这个块被执行了吗？ 我会放一个Log.d(TAG, "text length:" + mTxtReceive.getText().length()); 出于调试目的而超出条件。 最后一个明显的问题是txtLength是否比 max chars 更长（这将是一个包含 50000 个字符的相当长的文本）。 但是您也可以简单地使用块外的推荐日志进行验证。