使用InputStream和Scanner從.txt文件讀取數據android

Question

我無法從.txt文件讀取數據。當我運行應用程序時，出現錯誤消息，應用程序崩潰，我懷疑這是與讀取文本文件或將其從InputStream轉換爲掃描程序有關。我有以下代碼：

FileExaminer a = new FileExaminer(); 
FileExaminer b = new FileExaminer(); 
FileExaminer c = new FileExaminer(); 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     try{ 
      readFile.runMethods(); 
     } catch (Exception e) { 
      System.out.println("Error in Main"); 
     } 
    } 

---

public InputStream input; 
public Scanner file; 
AssetManager assetManager = getAssets(); 

public String a, b, c; 
public void runMethods() { 
    openFile(); 
    readFile(); 
    closeFile(); 
} 

public void openFile() { 
    try{ 
     input = getAssets().open("numbers.txt"); 
     file = new Scanner(input); 
    } catch(Exception e) { 
     System.out.println("error"); 
     } 
    } 

public void readFile() { 
    while (file.hasNext()) { 
     a = file.next(); 
     b = file.next(); 
     c = file.next(); 

     System.out.printf("%s %s %s/n", a,b,c); 
    } 
} 

public void closeFile() { 
    file.close(); 
} 

---

和我的錯誤日誌是這樣的：

07-01 02:10:05.113: D/AndroidRuntime(2174): Shutting down VM 
07-01 02:10:05.173: W/dalvikvm(2174): threadid=1: thread exiting with uncaught exception (group=0xb1cf6b20) 
07-01 02:10:05.213: E/AndroidRuntime(2174): FATAL EXCEPTION: main 
07-01 02:10:05.213: E/AndroidRuntime(2174): Process: com.aghgb.pokedex, PID: 2174 
07-01 02:10:05.213: E/AndroidRuntime(2174): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.aghgb.pokedex/com.aghgb.pokedex.Main}: java.lang.NullPointerException 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.ActivityThread.access$800(ActivityThread.java:135) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.os.Handler.dispatchMessage(Handler.java:102) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.os.Looper.loop(Looper.java:136) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at java.lang.reflect.Method.invokeNative(Native Method) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at java.lang.reflect.Method.invoke(Method.java:515) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at dalvik.system.NativeStart.main(Native Method) 
07-01 02:10:05.213: E/AndroidRuntime(2174): Caused by: java.lang.NullPointerException 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.content.ContextWrapper.getAssets(ContextWrapper.java:83) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at com.aghgb.pokedex.FileExaminer.<init>(FileExaminer.java:13) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at com.aghgb.pokedex.Main.<init>(Main.java:7) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at java.lang.Class.newInstanceImpl(Native Method) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at java.lang.Class.newInstance(Class.java:1208) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.Instrumentation.newActivity(Instrumentation.java:1061) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112) 
07-01 02:10:05.213: E/AndroidRuntime(2174):  ... 11 more 

在此先感謝。

Answer 1

用於讀取.txt文件，你可以使用這個方法：

try { 
    txtFileRead("filename.txt"); 
} catch (IOException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
} 


public List<String> txtFileRead(String filename) throws IOException { 
    List<String> readData = new ArrayList<String>(); 
    AssetManager assets = context.getAssets(); 
    BufferedReader reader = new BufferedReader(new InputStreamReader(assets.open(filename))); 
    while(true) { 
     String line = reader.readLine(); 
     if(line == null) { 
      break; 
     } 
     lines.add(line); 
    } 
    return lines; 
} 

在txtFileRead()我讀的文本文件，並添加讀取數據列出。

Answer 2

幾個小時的研究和反覆試驗後，我想出了這個：

try { 
     file = new Scanner(getResources().openRawResource(R.raw.pokemon_data)); 
     System.out.println("File Scanned"); 
     // do reading, usually loop until end of file reading 
     while (file.hasNext()) { 
      a = file.next(); 
      b = file.next(); 
      c = file.next(); 
      System.out.printf("%s %s %s\n", a, b, c); 
     } 
    } catch (Exception e) { 
     System.out.println("Error opening/reading file"); 
    } finally { 
     if (file != null) { 
      file.close(); 
     } 
    } 

此代碼用於打印出已存儲在列的文本文件中，只要工作的文件位於原始文件夾中。在while循環中添加更多變量將增加顯示的列數量。