ArrayList内の2つの連続する値の違い：Android

Question

私はArrayList()にリアルタイムで生成されたいくつかのデータを保存しています。 ----------------

：私は、私はこの

ArrayList<Long> difference = new ArrayList<>(); 
difference.add(durationInMs); 
//tried to store 
for (int d = 0; d < difference.size()-1; d++){ 
     time1 = difference.get(d); 
     time2 = difference.get(d + 1); 
     timeDifference = time2 - time1; 
} 

これを試してみましたArrayList

1. の連続した要素の違いを取得したいですまた

   ArrayList<Long> difference = new ArrayList<>(); 
   difference.add(durationInMs); 
   
   ArrayList<Long> tempArray = new ArrayList<>(); 
   tempArray.add(0, difference.get(0)); 
   
   for (int d = 0; d < difference.size()-1; d++){ 
        timeDifference = tempArray.get(d+1) - difference.get(d); 
   } 
   Log.d("time", String.valueOf(timeDifference)); 
   

2. この enter link description here

しかし、それらのうちの2つの連続した要素の間で減算された値が得られないようです。おそらく問題は、リアルタイムで値が生成されていることです。これを減算すると、次の値はまだ生成されていません。 どうすればいいですか？

UPDATE：方法（それが役立つ場合）

@Override 
public void onPreviewFrame(long startTime, int ySum, int uSum, int vSum, long endTime) { 
    begin = startTime; 
    img_Y_Avg = ySum; 
    img_U_Avg = uSum; 
    img_V_Avg = vSum; 
    end = endTime; 


    //set value of Y on the text view 
    TextView valueOfY = (TextView)findViewById(R.id.valueY); 
    //valueY = img_Y_Avg; 
    valueOfY.setText(Double.toString(img_Y_Avg)); 

    //set value of U on the text view 
    TextView valueOfU = (TextView)findViewById(R.id.valueU); 
    // valueU = img_U_Avg; 
    valueOfU.setText(Double.toString(img_U_Avg)); 

    //set value of V on the text view 
    TextView valueOfV = (TextView)findViewById(R.id.valueV); 
    //valueV = img_V_Avg; 
    valueOfV.setText(Double.toString(img_V_Avg)); 

    //start time in milliseconds 
    long StartDurationInMs = TimeUnit.MILLISECONDS.convert(begin, TimeUnit.MILLISECONDS); 
    ArrayList<Long> startOfTime = new ArrayList<>(); 
    startOfTime.add(StartDurationInMs); 
    Log.d("time", "start: "+String.valueOf(startOfTime)); 

    //store value to array list 
    ArrayList<Integer> yAverage = new ArrayList<>(); 
    yAverage.add(img_Y_Avg); 
    //Log.d("MyEntryData", String.valueOf(yAverage)); 

    //store u values to array 
    ArrayList<Integer> uAverage = new ArrayList<>(); 
    uAverage.add(img_U_Avg); 
    //Log.d("MyEntryData", String.valueOf(uAverage)); 

    //store u values to array 
    ArrayList<Integer> vAverage = new ArrayList<>(); 
    vAverage.add(img_V_Avg); 
    //Log.d("MyEntryData", String.valueOf(vAverage)); 
    //time between frames 

    //end time in milliseconds 
    long EndDurationInMs = TimeUnit.MILLISECONDS.convert(end, TimeUnit.MILLISECONDS); 
    ArrayList<Long> endOfTime = new ArrayList<>(); 
    endOfTime.add(EndDurationInMs); 


    Log.d("time", "end: "+String.valueOf(endOfTime)); 


    ArrayList<Long> getValues = new ArrayList<>(); 
    for(int i = 0; i < yAverage.size(); i++) { 
     getValues.add(startOfTime.get(i)); 
     getValues.add((long)(yAverage.get(i))); 
     getValues.add((long)(uAverage.get(i))); 
     getValues.add((long)(vAverage.get(i))); 
    } 


    String filename = new SimpleDateFormat("yyyyMMddHHmm'.csv'").format(new Date()); 

    File directoryDownload = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS); 
    File logDir = new File (directoryDownload, "bpReader"); //Creates a new folder in DOWNLOAD directory 
    logDir.mkdirs(); 
    File file = new File(logDir, filename); 

    FileOutputStream outputStream = null; 
    try { 
      outputStream = new FileOutputStream(file, true); 
      //outputStream = openFileOutput(filename, Context.MODE_PRIVATE); 
      for (int i = 0; i < yAverage.size(); i += 4) { 
       outputStream.write((getValues.get(i) + ",").getBytes()); 
       outputStream.write((getValues.get(i + 1) + ",").getBytes()); 
       outputStream.write((getValues.get(i + 2) + ",").getBytes()); 
       outputStream.write((getValues.get(i + 3) + "\n").getBytes()); 

      } 
      outputStream.close(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

    Log.d("MyEntryData", String.valueOf(getValues)); 


    handler = new Handler(); 
    final Runnable runnable = new Runnable() { 
     @Override 
     public void run() { 
      readingRemaining = readingRemaining -1; 

      if (readingRemaining > 0){ 
       plotGraph(img_Y_Avg); 
      } 
     } 
    }; 

    handler.postDelayed(runnable, 100); 

    //Log.d("MyEntryData", String.valueOf(img_Y_Avg +" "+ img_U_Avg+" "+img_V_Avg)); 

} 

Answer 1

長いデルタ= difference.get（D + 1）してみてください - difference.get（d）を、

ArrayList<Long> difference = new ArrayList<>(); 
    for (int i = 0; i<10; i++) 
     difference.add((long)(Math.random() * 1000)); 
    for (int d = 0; d < difference.size()-1; d++){ 
     Log.i("diff", String.format(
       "element %d,%d:%d - %d = %d", 
       d+1, d, difference.get(d+1), difference.get(d), 
       difference.get(d+1) - difference.get(d))); 
    } 
    Log.i(TAG, "hello"); 

出力：

... I/diff: element 1,0:197 - 425 = -228 
... I/diff: element 2,1:389 - 197 = 192 
... I/diff: element 3,2:947 - 389 = 558 
... I/diff: element 4,3:510 - 947 = -437 
... I/diff: element 5,4:399 - 510 = -111 
... I/diff: element 6,5:971 - 399 = 572 
... I/diff: element 7,6:537 - 971 = -434 
... I/diff: element 8,7:326 - 537 = -211 
... I/diff: element 9,8:897 - 326 = 571 

Answer 2

あなたがそれを処理しているように、アレイは、で、その後

提案1

をリアルタイムに変更されていることを懸念している場合新しいデータポイントが生成される時には、以前のデータポイントを見てデルタをオンザフライで計算し、デルタを別の配列に追加できますか？

long lastDatum = null; 
    ArrayList<long> diffArray = new ArrayList<>(); 

    void recordDataPoint(long datum) 
    { 
     if (lastDatum != null) { 
     diffArray.add(datum - lastDatum); 
     } 
     lastDatum = datum; 

     // ... do whatever else you need to do with datum.... 
    } 

提言2
配列が安定しているなら、私はあなただけでこれを実行する必要があると思う：

// existing data is in durationInMs[] 

    ArrayList<Long> difference = new ArrayList<>(); 

    for (int d = 0; d < durationInMs.size()-1; d++){ 
     time1 = durationInMs.get(d); 
     time2 = durationInMs.get(d + 1); 
     timeDifference = time2 - time1; 

     difference.add(timeDifference); 
}