java - Android 上的 onActivityResult 方法内的全局变量值未更改

Question

我的 Java 代码中的全局变量出现问题。事情是这样的:我的屏幕有 3 个 ImageButtons 元素，按下时可以选取 3 个图像；这很好用。我使用 onActiviyResult 来实现它，但我只为 3 个图像实现了一个 onActiviyResult 方法，因此我在方法中使用 3 个 if(){...} block 来了解按下的图像按钮，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);
}

这里，current_picture是一个String，它是在onCreate方法之外声明的，它的默认值设置为:String current_picture = "";

我使用此变量来保存在 3 个图像按钮的 setonclicklistener 事件上设置的值，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);


        }
    });

imagebutton2 (current_picture = "pic2";) 和 imagebutton3 (current_picture = "pic3";) 也是如此。显然，所有这些事件都在 onCreate 方法上。

所以，问题是，在调用 onActivityResult 方法时，current_picture 正在丢失其在 setonclicklistener 方法上设置的值，我的意思是，current_user 值仍然是“”，而不是“pic1”、“pic2”或“pic3”，具体取决于按下的按钮图像按钮。我认为它的值在调用新 Activity onActivityResult时被破坏，然后onActivityResul只识别:String current_picture = "";

我做了很多事情来解决这个问题，但我能够找到解决方案，我在下面附加了一些代码(不是全部，只是重要部分):

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

您可以使用不同的请求代码启动 Activity 。

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
          }
       }
   }

}