UIスレッドからメソッドを呼び出す必要があります。現在推定されているスレッドはworkerです

Question

キャンバスに円を描こうとしています。現在、私はボタンクリックでそれを行うことができますが、Fragmentがロードされているときも同じことをする必要があります。以下は私のFragmentコードです。以下は

public class StepTwentyOneFragment extends Fragment { 

    private CanvasView customCanvas; 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View v = inflater.inflate(R.layout.step21_fragment, container, false); 
     customCanvas=(CanvasView)v.findViewById(R.id.signature_canvas); 

     final Button button1=(Button)v.findViewById(R.id.step18button1); 


     float radius=(customCanvas.getCanvasWidth()/2) - ((customCanvas.getCanvasWidth()/2)/100)*60; 
     new MyAsyncTask(customCanvas).execute(); 

     button1.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View v) { 

       if(v.getId()==R.id.step18button1){ 

        float radius=(customCanvas.getCanvasWidth()/2) - ((customCanvas.getCanvasWidth()/2)/100)*60; 
        customCanvas.drawCircle(radius); 
        Log.d("An_Width", "" + customCanvas.getCanvasWidth()); 
        Log.d("An_Height" ,""+ customCanvas.getCanvasHeight()); 

        v.setBackgroundResource(R.drawable.button_border_5); 
        button1.setTextColor(Color.WHITE); 


       } 
      } 
     }); 






     return v; 
    } 

    public static StepTwentyOneFragment newInstance() { 

     StepTwentyOneFragment f = new StepTwentyOneFragment(); 
     Bundle b = new Bundle(); 

     f.setArguments(b); 

     return f; 
    } 


    @Override 
    public void setUserVisibleHint(boolean isVisibleToUser) { 
     super.setUserVisibleHint(isVisibleToUser); 
     if(isVisibleToUser) { 
      Activity a = getActivity(); 
      if(a != null) a.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT); 
     } 
    } 

    public class MyAsyncTask extends AsyncTask<Void, Void, Void> { 

     CanvasView myTaskView; 

     MyAsyncTask(CanvasView v){ 
      myTaskView = v; 
     } 

     @Override 
     protected Void doInBackground(Void... arg0) { 

      myTaskView.drawCircle(150); 
      return null; 
     } 

    } 

} 

私Fragmentにしかし私Canvasコード

public class CanvasView extends View { 

    public int width; 
    public int height; 
    private Bitmap mBitmap; 
    private Canvas mCanvas; 
    private Path mPath; 
    Context context; 
    private Paint mPaint; 
    private float mX, mY; 
    private static final float TOLERANCE = 5; 
    private int canvasHeight, canvasWidth; 
    private float radius; 

    public CanvasView(Context c, AttributeSet attrs) { 
     super(c, attrs); 
     context = c; 

     mPath = new Path(); 

     mPaint = new Paint(); 
     mPaint.setStrokeWidth(3); 
     mPaint.setColor(Color.CYAN); 
    } 

    // override onDraw 
    @Override 
    protected void onDraw(Canvas canvas) { 

     super.onDraw(canvas); 

     mCanvas=canvas; 

     Drawable d = getResources().getDrawable(R.drawable.circle_1); 

     canvasHeight= canvas.getHeight(); 
     canvasWidth= canvas.getWidth(); 

     Log.d("Height - ","/"+canvas.getHeight()); 
     Log.d("Width - ","/"+canvas.getWidth()); 

//   DisplayMetrics displaymetrics = new DisplayMetrics(); 
//  ((Activity)context).getWindowManager().getDefaultDisplay().getMetrics(displaymetrics); 
//  int height = displaymetrics.heightPixels; 
//  int width = displaymetrics.widthPixels; 

     float h=canvasHeight/2; 
     float w=canvasWidth/2; 


     d.setBounds(0, 0, canvasWidth, canvasHeight); 
     d.draw(canvas); 

     canvas.drawCircle(w, h, radius, mPaint); 
    } 

    public void clear2(){ 
     radius=0; 
     //important. Refreshes the view by calling onDraw function 
     invalidate(); 

    } 

    public void drawCircle(float radius1) { 

     radius=radius1; 
     //important. Refreshes the view by calling onDraw function 
     invalidate(); 

    } 

    public int getCanvasHeight() 
    { 
     return canvasHeight; 
    } 

    public int getCanvasWidth() 
    { 
     return canvasWidth; 
    } 

} 

で、MyAsyncTaskの内側には、エラーコードの行のMethod drawCircle must be called from the UI thread, currently inferred thread is workermyTaskView.drawCircle(150);

は、私はこれをどのように修正することができます示して？

Answer 1

doInBackground（）で実装している場合は、UIスレッドに何も表示できません。それはバックグラウンドタスクです。 UIを更新するには、postexecute（）でメソッドを実装する必要があります。

AsyncTaskについて詳しく読む：https://developer.android.com/reference/android/os/AsyncTask.html

クリアあなたの概念は、AsynTaskを使用することが容易になります。

基本AsyncTaskの構造：

private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> { 
    protected Long doInBackground(URL... urls) { 
     int count = urls.length; 
     long totalSize = 0; 
     for (int i = 0; i < count; i++) { 
      totalSize += Downloader.downloadFile(urls[i]); 
      publishProgress((int) ((i/(float) count) * 100)); 
      // Escape early if cancel() is called 
      if (isCancelled()) break; 
     } 
     return totalSize; 
    } 

    protected void onProgressUpdate(Integer... progress) { 
     setProgressPercent(progress[0]); 
    } 

    protected void onPostExecute(Long result) { 
     showDialog("Downloaded " + result + " bytes"); 
    } 
}