如果文件不存在，则创建它并将字符串写入其中。如果确实如此，则将字符串附加到它。工作不正常
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【中文标题】如果文件不存在，则创建它并将字符串写入其中。如果确实如此，则将字符串附加到它。工作不正常【英文标题】：If file does not exist, create it and write string to it. If it does then append string to it. Isn't working right 【发布时间】：2013-04-07 14:41:52 【问题描述】：好的，我阅读了很多，并认为我已经解决了这个问题，但显然没有。我要做的是检查文件是否存在（在本例中为 heapFile.csv），如果不存在，则创建它，然后向其写入字符串。如果文件确实存在，那么我想将字符串附加到文件中。当我运行它时，我没有收到任何错误，尽管我确实收到警告说它无法创建文件，尽管它确实这样做了。但是，无论哪种情况，它都不会将字符串写入文件。我可能只是没有使用正确的语法或其他东西，但是在盯着这个看了几个星期之后，我看不到树木的森林并找到了问题。除了这个问题，我的程序运行良好，如果我能正常工作，我终于可以完成这个。非常感谢任何帮助。
这是 java 文件。我认为文件创建/写入位在哪里很清楚。
package com.loch.meaptracker;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import com.google.ads.*;
import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.DatePicker;
import android.widget.EditText;
import android.widget.RelativeLayout;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.TimePicker;
public class MainActivity extends Activity implements OnSeekBarChangeListener
private SeekBar happyBar, energyBar, anxietyBar, painBar;
private EditText noteField;
private DatePicker dPick;
private TimePicker tPick;
@SuppressWarnings("unused")
private Button enterButton;
private int happyValue = 4, energyValue = 4, anxietyValue = 4,
painValue = 4;
private static final String TAG = "heapApp";
private String Mood = "Blah";
private AdView adView;
final Context context = this;
@Override
protected void onCreate(Bundle savedInstanceState)
try
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Create the adView
adView = new AdView (this, AdSize.BANNER, "a15138b1a7adad2");
// Lookup your RelativeLayout assuming it's been given the attribute android:id="@+id/AdRelativeLayout
RelativeLayout layout = (RelativeLayout)findViewById(R.id.AdRelativeLayout);
// Add the AdView to it
layout.addView(adView);
// Initiate a generic request to load it with an ad
adView.loadAd(new AdRequest());
// bars
happyBar = (SeekBar) findViewById(R.id.happinessBarID);
happyBar.setOnSeekBarChangeListener(this);
energyBar = (SeekBar) findViewById(R.id.energyBarID);
energyBar.setOnSeekBarChangeListener(this);
anxietyBar = (SeekBar) findViewById(R.id.anxietyBarID);
anxietyBar.setOnSeekBarChangeListener(this);
painBar = (SeekBar) findViewById(R.id.painBarID);
painBar.setOnSeekBarChangeListener(this);
// end bars
dPick = (DatePicker) findViewById(R.id.datePicker1);
tPick = (TimePicker) findViewById(R.id.timePicker1);
noteField = (EditText) findViewById(R.id.noteTextFieldID);
enterButton = (Button) findViewById(R.id.enterButtonID);
catch (Exception onCreateException)
Log.e(TAG, "Exception received", onCreateException);
@Override
public boolean onCreateOptionsMenu(Menu menu)
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
// Bar listener methods
@Override
public void onProgressChanged(SeekBar arg0, int barValue, boolean hFromUser)
try
switch (arg0.getId())
case R.id.happinessBarID:
happyValue = barValue + 1;
break;
case R.id.energyBarID:
energyValue = barValue + 1;
break;
case R.id.anxietyBarID:
anxietyValue = barValue + 1;
break;
case R.id.painBarID:
painValue = barValue + 1;
break;
String debugBarValue = "Happy is " + happyValue + ", Energy is "
+ energyValue + ", Anxiety is " + anxietyValue
+ ", Pain is " + painValue + ".";
System.out.println(debugBarValue);
catch (Exception BarValueException)
Log.e(TAG, "Exception received", BarValueException);
@Override
public void onStartTrackingTouch(SeekBar happyBar)
// TODO Auto-generated method stub
@Override
public void onStopTrackingTouch(SeekBar happyBar)
// TODO Auto-generated method stub
// end Bar listener methods
// Enter Button listener Method
public void dialogPop(View v)
try
AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(
context);
// set Title
alertDialogBuilder.setTitle("title");
// set dialog message
alertDialogBuilder.setMessage("You entered: " + getMood())
.setCancelable(false).setPositiveButton("Okay",
// When Okay button clicked the write mood string to file
new DialogInterface.OnClickListener()
public void onClick(DialogInterface dialog,
int id)
try
// This is the string that should be
// written to file
String data = getMood();
// This is the file that should be
// written to
File heapFile = new File(Environment.getExternalStorageDirectory(), "heapFile.csv");
// if file doesn't exists, then create
// it
if (!heapFile.exists())
heapFile.createNewFile();
FileWriter heapFileWritter = new FileWriter(
heapFile.getName(), true);
BufferedWriter heapBufferWritter = new BufferedWriter(
heapFileWritter);
heapBufferWritter.write(data);
heapBufferWritter.close();
System.out.println("Done");
// true = append file
FileWriter heapFileWritter = new FileWriter(
heapFile.getName(), true);
BufferedWriter heapBufferWritter = new BufferedWriter(
heapFileWritter);
heapBufferWritter.write(data);
heapBufferWritter.close();
System.out.println("Done");
catch (IOException e)
e.printStackTrace();
)
// If they press either the cancel button or the back button
// on their device (Same thing) then close the dialog and
// give the user a chance to change what they've entered
.setNegativeButton("Cancel",
new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog,
int id)
// TODO Auto-generated method stub
dialog.cancel();
);
// create alert dialog
AlertDialog alertDialog = alertDialogBuilder.create();
// show it
alertDialog.show();
catch (Exception buttonListenerException)
Log.e(TAG, "Exception received", buttonListenerException);
return;
public String getMood()
try
int month = dPick.getMonth();
int day = dPick.getDayOfMonth();
int year = dPick.getYear();
int minute = tPick.getCurrentMinute();
String moodAntePost = "AM";
boolean hourType = tPick.is24HourView();
int moodHour = tPick.getCurrentHour();
if (hourType == false && moodHour > 12)
moodHour = (moodHour - 12);
moodAntePost = "PM";
else if (hourType == false && moodHour <= 0)
moodHour = 12;
else
String noteText = noteField.getText().toString();
Mood = "Happiness," + happyValue + ",Energy," + energyValue
+ ",Anxiety," + anxietyValue + ",Pain," + painValue
+ ",Date," + month + "/" + day + "/" + year + ",Time,"
+ moodHour + ":" + minute + "," + moodAntePost + ",Note,"
+ noteText;
System.out.println(Mood);
catch (Exception getMoodException)
Log.e(TAG, "Exception received", getMoodException);
return Mood;
编辑了我的问题以包含清单，以便您可以查看我拥有的权限。我认为它是正确的，但我不确定......
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.loch.meaptracker"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.loch.meaptracker.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="com.google.ads.AdActivity"
android:configChanges="keyboard|keyboardHidden|orientation|screenLayout|uiMode|screenSize|smallestScreenSize"/>
</application>
</manifest>
【问题讨论】：
快速提问，您是否添加了WRITE_EXTERNAL_STORAGE 和READ_EXTERNAL_STORAGE 的权限？
哦，对了！让我编辑并将我的清单包含在问题中。虽然我认为我做的没错。
我实际上不需要包含读取外部存储的权限，因为我实际上并不需要相关文件的内容。反正还没有。当我包含一些我计划的其他功能时，我将需要在该程序的更高版本中这样做。
【参考方案1】：
使用这个：
String file = heapFile.getAbsolutePath();
FileWriter heapFileWritter = new FileWriter(file, true);
getName() 只会给你文件的名称。但是您需要为 FileWriter 提供绝对路径。
【讨论】：
好吧，你的建议奏效了，但由于某种原因它写了两次字符串。 >_ facepalm 我是个白痴。我现在明白为什么它做了两次。非常感谢。我想这会完成它。 对于任何阅读本文的人来说，这仅仅是因为我忽略了将 if do this stuff 之后的代码包装在 else 中。一旦我这样做了，它就完美地工作了。以上是关于如果文件不存在，则创建它并将字符串写入其中。如果确实如此，则将字符串附加到它。工作不正常的主要内容，如果未能解决你的问题，请参考以下文章
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