我正在尝试创建一个具有开始和停止按钮的应用程序，该按钮收集加速度计数据并在表格中显示x，y和z坐标。每次传感器检测到变化时，都应添加一组带有新坐标的行。最初，我没有包含按钮或onPause（）或onResume（）方法，并且动态添加行。但是，由于添加了很多行，应用程序会冻结并耗尽电池电量。因此，我添加了onPause和onResume方法，以及用于记录数据的开始和停止按钮。不幸的是，按钮工作但数据行在屏幕满了行后停止变化。我使用LogCat检查是否正在添加行，它们是。我只是不知道为什么他们不会全部出现。我的代码粘贴在下面。布局文件位于同一代码块中的java文件之后。任何帮助将不胜感激！
package com.explorer.extractor;
//import packages
import android.app.ActionBar;
import android.content.Context;
import android.graphics.Color;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Calendar;
public class MainActivity extends ActionBarActivity implements SensorEventListener,OnClickListener {
Button button1;
Button button2;
private SensorManager mSensorManager;
Sensor accelerometer;
private static final String TAG = MainActivity.class.getName();
private static final String FILENAME = "myFile.txt"; //file where data is written
//layout variables
TableLayout t1;
TextView dataReading; //declare data text object
Integer count = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//initialize sensor manager
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
//initialize accelerometer
accelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
//mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_FASTEST);
t1 = (TableLayout) findViewById(R.id.main_table);
button1 = (Button) findViewById(R.id.button1);
button2 = (Button) findViewById(R.id.button2);
button1.setOnClickListener(this);
button2.setOnClickListener(this);
}
public void onAccuracyChanged(Sensor sensor, int accuracy){}
/**onResume() registers the accelerometer for listening
* to the events
*/
protected void onResume(){
super.onResume();
mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_FASTEST);
}
protected void onPause(){
super.onPause();
mSensorManager.unregisterListener(this);
}
public void onSensorChanged(SensorEvent event){
//if sensor status result is unreliable return
if (event.accuracy == SensorManager.SENSOR_STATUS_UNRELIABLE){
return;
}
Sensor sensor = event.sensor;
//check sensor type
if (sensor.getType() == Sensor.TYPE_ACCELEROMETER){
//assign directions
float x = event.values[0];
float y = event.values[1];
float z = event.values[2];
try {
//write to text file the x, y, and z values each type a sensor detects change
writeToFile(Float.toString(x), Float.toString(y), Float.toString(z));
//return string of text file
String textFromFileString = readFromFile();
TableRow tr = new TableRow(this);
if(count%2!=0) {
tr.setBackgroundColor(Color.GRAY);
}
tr.setId(100 + count);
tr.setLayoutParams(new TableRow.LayoutParams(TableRow.LayoutParams.MATCH_PARENT, TableRow.LayoutParams.WRAP_CONTENT));
//show data read from file
dataReading = new TextView(this);
dataReading.setId(200 + count);
dataReading.setText(textFromFileString);
dataReading.setPadding(2, 0, 5, 0);
dataReading.setTextColor(Color.WHITE);
tr.addView(dataReading);
//finally add data to table row
t1.addView(tr, new TableLayout.LayoutParams(ActionBar.LayoutParams.MATCH_PARENT, ActionBar.LayoutParams.WRAP_CONTENT));
count++;
Log.i("LIMA","Add row. There are now " + t1.getChildCount()+"rows");
}catch (IOException e) {
e.printStackTrace();
}
}
}
public void onClick(View v) {
switch (v.getId()) {
case R.id.button1:
mSensorManager.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_FASTEST);
break;
case R.id.button2:
mSensorManager.unregisterListener(this);
}
}
/**
* writeToFile: writes data recordings of accelerometer to text file
* @param x
* @param y
* @param z
* @throws IOException
*/
void writeToFile(String x, String y, String z) throws IOException {
//get exact instance of time in which call to write is being made
Calendar c = Calendar.getInstance();
//create string to print to text using values in parameter
String s = c.get(Calendar.HOUR) + ":" + c.get(Calendar.MINUTE) + ":" + c.get(Calendar.SECOND) + ":" + c.get(Calendar.MILLISECOND) + " - " + "x: " + x + " y: " + y + " z: " + z + "\n";
try {
//append new string to file
OutputStreamWriter outputStreamWriter = new OutputStreamWriter(openFileOutput(FILENAME, Context.MODE_PRIVATE));
BufferedWriter bw = new BufferedWriter(outputStreamWriter);
bw.write(s);
bw.flush();
bw.close();
} catch(IOException e) {
Log.e(TAG, "File write failed: " + e.toString());
}
}
private String readFromFile(){
String ret = "";
try {
//open text file to read from
InputStream inputStream = openFileInput(FILENAME);
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
String receiveString = "";
StringBuilder stringBuilder = new StringBuilder();
while ((receiveString = bufferedReader.readLine()) != null) {
//continue appending to stringBuilder until you've reached the end of file
stringBuilder.append(receiveString);
}
inputStream.close();
ret = stringBuilder.toString();
}
} catch (FileNotFoundException e) {
Log.e(TAG, "File not found: " + e.toString());
} catch (IOException e) {
Log.e(TAG, "Can not read file: " + e.toString());
}
return ret;
}
}
Here is my layout file:
<?xml version="1.0" encoding="utf-8"?>
<TableLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/main_table"
android:layout_weight="1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:shrinkColumns="*"
android:stretchColumns="*">
<TableRow
android:id="@+id/tablerow"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button
android:id="@+id/button1"
android:layout_height="wrap_content"
android:text="Start"
android:layout_weight=".5"
android:layout_width="match_parent"
android:gravity="center_horizontal"/>
<Button
android:id="@+id/button2"
android:layout_height="wrap_content"
android:text="Stop"
android:layout_weight=".5"
android:layout_width="match_parent"
android:gravity="center_horizontal"/>
</TableRow>
</TableLayout>
答案 0 :(得分：0)
要回答您的问题：您需要将TableLayout包裹在ScrollView中：
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TableLayout
android:id="@+id/main_table"
...
但是，您的代码存在一些问题： - ）
可能最严重的是：不要在主线程上执行任何I / O.即不读/写主/ UI线程上的文件。在Android中创建线程有很多种方法，但有两个例子是AsyncTask和RxJava / RxAndroid。您可以在logcat日志中看到这是一个问题，例如：
I/Choreographer﹕ Skipped 34 frames! The application may be doing too much work on its main thread.
记录收到的每个事件并不是一个好主意，因为当您使用SensorManager.SENSOR_DELAY_FASTEST时，会非常频繁地收到accellerometer事件。即使您降低了频率，在UI列表中添加成千上万的条目仍然不是一个好主意。您可能只想显示最后x个条目，并且出于UI目的，即使您想要登录文件，您也不需要每秒1或2个条目或类似的东西。更频繁。
TextView dataReading不应该是成员字段 - 只需将其声明为需要的本地变量。始终声明变量尽可能接近它们的使用位置。TableLayout用作表格，常规ListView就足够了。AsyncTask或其他一些线程机制在后台线程中写入文件。@Override注释，例如适用于onResume和onPause。