全局變量值onActivityResult內部沒有改變Android上的方法

Question

我在Java代碼中遇到全局變量問題。這裏是一件事：我的屏幕有3個ImageButtons元素用於在按下時選擇3張圖像;這工作正常。我使用onActiviyResult來創建它，但是我爲這3個圖像實現了一個onActiviyResult方法，所以我在方法中使用了3個if（）{...}塊來知道按下的按鈕，我的意思是：

if(current_picture.equals("pic1"))}{ 
    imagebutton1.setImageBitmap(bitmap); 
} 

if(current_picture.equals("pic2"))}{ 
    imagebutton2.setImageBitmap(bitmap); 
} 

if(current_picture.equals("pic3"))}{ 
    imagebutton3.setImageBitmap(bitmap); 
} 

這裏，current_picture是一個字符串，它的聲明的onCreate方法外，它的默認值設置爲：字符串current_picture =「」;

我使用這個變量來保存這是在3個imagebuttons的setonclicklistener事件設置的值，我的意思是：

imagebutton1.setOnClickListener(new View.OnClickListener() { 

    @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      current_picture = "pic1";                 
      Intent intent = new Intent(); 
      intent.setType("image/*"); 
      intent.setAction(Intent.ACTION_GET_CONTENT); 
      startActivityForResult(Intent.createChooser(intent, "Choose a 
      picture"), SELECT_PICTURE); 


     } 
    }); 

爲imagebutton2（current_picture = 「PIC2」）

同樣的事情，imagebutton3（current_picture =「pic3」;）。所有這些事件都明顯在onCreate方法上。

因此，問題是當調用onActivityResult方法時，current_picture在setonclicklistener方法上丟失了其設置的值，我的意思是，current_user值仍然是「」而不是「pic1」，「pic2」或「pic3」，具體取決於按下圖像按鈕。我認爲它的價值在調用onActivityResult的新活動時被破壞，然後onActivityResul只是識別：String current_picture =「」;

我已經做了很多事情來解決這一點，但我能夠找到一個解決方案，我連着下面的一些代碼（不是全部，只是重要的部分）：

public class Publish_Event extends Activity{ 

    private ImageButton imagebutton1; 
    private ImageButton imagebutton2; 
    private ImageButton imagebutton3; 
    private Bitmap bitmap; 
    private String current_picture=""; 


    protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.publicar_eventos); 

    StrictMode.ThreadPolicy p = new 
    StrictMode.ThreadPolicy.Builder().permitAll().build(); 
    StrictMode.setThreadPolicy(p); 

    imagebutton1 = (ImageButton)findViewById(R.id.pic1); 
    imagebutton2 = (ImageButton)findViewById(R.id.pic2); 
    imagebutton3 = (ImageButton)findViewById(R.id.pic3); 


    imagebutton1.setOnClickListener(new View.OnClickListener() { 

    @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      current_picture = "pic1";                 
      Intent intent = new Intent(); 
      intent.setType("image/*"); 
      intent.setAction(Intent.ACTION_GET_CONTENT); 
      startActivityForResult(Intent.createChooser(intent, "Choose a 
      picture"), SELECT_PICTURE); 


     } 
    }); 


    imagebutton2.setOnClickListener(new View.OnClickListener() { 

    @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      current_picture = "pic2";                 
      Intent intent = new Intent(); 
      intent.setType("image/*"); 
      intent.setAction(Intent.ACTION_GET_CONTENT); 
      startActivityForResult(Intent.createChooser(intent, "Choose a 
      picture"), SELECT_PICTURE); 


     } 
    }); 

    imagebutton3.setOnClickListener(new View.OnClickListener() { 

    @Override 
     public void onClick(View v) { 
      // TODO Auto-generated method stub 
      current_picture = "pic3";                 
      Intent intent = new Intent(); 
      intent.setType("image/*"); 
      intent.setAction(Intent.ACTION_GET_CONTENT); 
      startActivityForResult(Intent.createChooser(intent, "Choose a 
      picture"), SELECT_PICTURE); 


     } 
    }); 


    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent 
    data) { 
      super.onActivityResult(requestCode, resultCode, data); 
      if (resultCode == Activity.RESULT_OK) { 
       if (requestCode == SELECT_PICTURE) { 
        Uri selectedImageUri = data.getData(); 
        imagen_path = getRealPathFromURI(selectedImageUri); 
        bitmap = BitmapFactory.decodeFile(imagen_path); 




        if(current_picture.equals("pic1")){ 

         imagebutton1.setImageBitmap(bitmap); 


        } 

        if(current_picture.equals("pic2")){ 

         imagebutton2.setImageBitmap(bitmap); 


        } 

        if(current_picture.equals("pic3")){ 

         imagebutton3.setImageBitmap(bitmap); 


        } 



       } 
      } 
     } 

    @TargetApi(Build.VERSION_CODES.KITKAT) 
    public String getRealPathFromURI(Uri contentUri) { 


     String[] projection = { MediaStore.Images.Media.DATA }; 
     Cursor cursor = null; 
     try { 
      if (Build.VERSION.SDK_INT > 19) { 
       // Will return "image:x*" 
       String wholeID = DocumentsContract.getDocumentId(contentUri); 
       // Split at colon, use second item in the array 
       String id = wholeID.split(":")[1]; 
       // where id is equal to 
       String sel = MediaStore.Images.Media._ID + "=?"; 

       cursor = Publish_Event.this.getContentResolver().query(
         MediaStore.Images.Media.EXTERNAL_CONTENT_URI, 
         projection, sel, new String[] { id }, null); 
      } else { 
       cursor = 

        Publish_Event.this.getContentResolver().query(contentUri, 
        projection, null, null, null); 
      } 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

     String path = null; 
     try { 
      int column_index = 
      cursor.getColumnIndex(MediaStore.Images.Media.DATA); 
      cursor.moveToFirst(); 
      path = cursor.getString(column_index).toString(); 
      cursor.close(); 
     } catch (NullPointerException e) { 
      e.printStackTrace(); 
     } 
     return path; 
    } 


} 

Answer 1

你可以用不同的請求代碼開始活動。

public class Publish_Event extends Activity{ 
    private static final int SELECT_PICTURE_1 = 1; 
    private static final int SELECT_PICTURE_2 = 2; 
    private static final int SELECT_PICTURE_3 = 3; 

    protected void onCreate(Bundle savedInstanceState) { 
     imagebutton1.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       Intent intent = new Intent(); 
       intent.setType("image/*"); 
       intent.setAction(Intent.ACTION_GET_CONTENT); 
       startActivityForResult(Intent.createChooser(intent, "Choose a picture"), SELECT_PICTURE_1); 
      } 
     }); 
     imagebutton2.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       Intent intent = new Intent(); 
       intent.setType("image/*"); 
       intent.setAction(Intent.ACTION_GET_CONTENT); 
       startActivityForResult(Intent.createChooser(intent, "Choose a picture"), SELECT_PICTURE_2); 
      } 
     }); 
    } 

    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) { 
     super.onActivityResult(requestCode, resultCode, data); 
     if (resultCode == Activity.RESULT_OK) { 
      if (requestCode == SELECT_PICTURE_1) { 
       //change imagebutton1 
      }else if(requestCode == SELECT_PICTURE_2){ 
      //change imagebutton2 
      }else if(requestCode == SELECT_PICTURE_3){ 
      //change imagebutton3 
      } 
     } 
    } 

}