用Java写入文本文件

Question

我有一个需要经验丰富的Java专业人士的应用程序。引擎工作得很完美，但我无法将数据保存到文本文件中;此外，每次调试文件操作时，我都必须拴好我的平板电脑，卸载旧的应用程序，复制apk并重新安装，因为我无法在模拟器中写入磁盘。

我补充说:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

到应用程序标记外部的清单中，并尝试了许多写入文件的方法。异常是(取决于当前的尝试)访问或文件不存在。我还在谷歌上搜索了一整天来寻找解决方案。有人知道吗?

// this is a canned method that should presumably work
 private void writeStringToTextFile(String s, String f){
File sdCard = Environment.getExternalStorageDirectory();
File dir = new File (sdCard.getAbsolutePath());
dir.mkdirs();
File file = new File(dir, f);
try{
    FileOutputStream f1 = new FileOutputStream(file,false); //True = Append to file, false = Overwrite
    PrintStream p = new PrintStream(f1);
    p.print(s);
    p.close();
    f1.close();
} catch (FileNotFoundException e) {
} catch (IOException e) {
}   }

// this is the save method
// it has been modified a little less than a million times today
// some lines may be unnecessary because I have tried several approaches
  public void saveSystem(View view){
          String s="";
          String FILENAME = "data/data/TopExpertAndroid/" + fileName;
          FileOutputStream f;
          File file = new File(FILENAME);
          if(!(file.exists())){
             try{
                 file.createNewFile();} 
             catch(Exception e){
                showSplash(e.getMessage() + e.getCause(), "OK");
                return;}}
          try{
              getFile();
              if(fileName.equals("")){}
              else{
                   f = openFileOutput(FILENAME, Context.MODE_PRIVATE);
                   for(int temp=0; temp<50; temp++){
                       for(int loop=0; loop<50; loop++){
                           s += topExpert.nodeBank[temp][loop].activationResponse + "n";
                           s += topExpert.nodeBank[temp][loop].display + "n";
                           s += topExpert.nodeBank[temp][loop].falseLink + "n";
                           s += topExpert.nodeBank[temp][loop].identifier + "n";
                           if(topExpert.nodeBank[temp][loop].isTop){
                              s += "true";}
                           else{
                                s += "false";}
                           s += "n" + topExpert.nodeBank[temp][loop].trueLink + "n";}}
                           writeStringToTextFile(s,FILENAME);
              }}
          catch(Exception e){
                showSplash(e.getMessage() + e.getCause(), "OK");}}

Answer 1

FILENAME变量可能在开始时缺少/:

String FILENAME = "/data/data/TopExpertAndroid/" + fileName;

你可能应该使用getDataDirectory或getExternalStorageDirectory来代替…

但是你说的不能写到模拟器的磁盘似乎很奇怪…?