android - getStringExtra() 返回 null

Question

我尝试通过 Intent 向函数发送额外的字符串数据，但我收到的是空值。

这里是 intent.put:

 private void takePicFromGallery(String nameOfButton) {
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    **intent.putExtra(NAME_OF_BUTTON, nameOfButton.toString());**
    startActivityForResult(intent.createChooser(intent, "choose picture"), PICK_FROM_GALLERY);

这里是获取:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    String nameOfButton = data.getStringExtra(NAME_OF_BUTTON);
    switch (nameOfButton) {
        case "ibMainPicture": {
            ibMainPicture.setImageBitmap(bitmap);
            break;
        }
        case "imageButton1": {
            imageButton1.setImageBitmap(bitmap);
            break;
        }

Answer 1

在 onActivityResult 期间收到的 Intent 与您在 takePicFromGallery 方法中创建的 Intent 不同。您启动的 Intent 被打开的 Activity 使用，并将新的 Intent 发送回您的应用程序。

选项 1(首选选项):

private static final int IB_MAIN_PICTURE_REQUEST_CODE = 524;
private static final int IMAGE_BUTTON_1_REQUEST_CODE = 785;

private void takePicFromGallery(String nameOfButton) {
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    if(nameOfButton.equals("ibMainPicture")) {
        startActivityForResult(intent.createChooser(intent, "choose picture"), IB_MAIN_PICTURE_REQUEST_CODE);
    else if(nameOfButton.equals("imageButton1") {
        startActivityForResult(intent.createChooser(intent, "choose picture"), IMAGE_BUTTON_1_REQUEST_CODE);
    }

然后在得到结果时:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if(resultCode == Activity.RESULT_OK) {
        if(requestCode == IB_MAIN_PICTURE_REQUEST_CODE) {
            ibMainPicture.setImageBitmap(bitmap);
        } else if(requestCode == IMAGE_BUTTON_1_REQUEST_CODE) {
            imageButton1.setImageBitmap(bitmap);
        }
    }
}

选项 2:

private static String lastButtonClicked = null;

private void takePicFromGallery(String nameOfButton) {
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    lastButtonClicked = nameOfButton.toString();
    startActivityForResult(intent.createChooser(intent, "choose picture"), PICK_FROM_GALLERY);
}

然后在得到结果时:

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if(lastButtonClicked == null || resultCode != Activity.RESULT_OK || requestCode != PICK_FROM_GALLERY) {
        return;
    }
    switch (lastButtonClicked) {
        case "ibMainPicture": {
            ibMainPicture.setImageBitmap(bitmap);
            break;
        }
        case "imageButton1": {
            imageButton1.setImageBitmap(bitmap);
            break;
        }
        ...
}