我有DialogFragment，可以选择使用startActivityForResult选择文件。然后我使用onActivityResult来接收数据和请求代码。使用filemanager选择文件后，我从onActivityResult访问它。现在选择的实际文件没有做太多，因为主要的问题是当文件进来时我可以得到它的名字，其他的东西。现在我将其添加到HashMap<String, Object>中，然后将其添加到ArrayList<HashMap<String, Object>>。然后，我想使用带有自定义xml布局的SimpleAdapter来填充列表视图。问题是SimpleAdapter需要上下文作为参数。我怎样才能在onActivityResult（）中接收上下文？
一些代码可以更好地了解我正在做的事情：
public class MyFragment extends DialogFragment {
...
...
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
...
//here I want to get the context
SimpleAdapter simpleAdapter = new SimpleAdapter(thecontext, attachments_list, R.layout.mycustomlayout, keys, ids);
...
}
}
更新：
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.SimpleAdapter.notifyDataSetChanged()' on a null object reference
更新完整代码：
public class MyFragment extends DialogFragment {
//code for whole activity
public static final String NEW_NOTE_CARD_FRAGMENT_CODE = "1";
//codes for each menu button
public static final String PICK_FILE_REQ_CODE = "2";
public static final String PICK_NEW_IMAGE_CODE = "3";
//attachment keys
public static final String KEY_ATTACHMENT_NAME = "a_name";
public static final String KEY_ATTACHMENT_DATE_ADDED = "a_date_added";
public static final String KEY_ATTACHMENT_ICON = "a_icon";
ArrayList<HashMap<String, Object>> attachmentsListArray = new ArrayList<HashMap<String, Object>>();
//listview
ListView attachmentsListView;
SimpleAdapter simpleAdapter;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.newnotecard, container, false);
//dialog customizations
getDialog().getWindow().requestFeature(Window.FEATURE_NO_TITLE);
// set color transparent
getDialog().getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
final ImageButton addNewAttachment = (ImageButton) v.findViewById(R.id.addNewAttachment);
//addNewAttachment
addNewAttachment.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//this adds the an xml layout to a linearlayout which is the layout of this dialog
//new attachment window
LayoutInflater thismenulayoutinflater = (LayoutInflater) getActivity().getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View newnoteattachment_window = thismenulayoutinflater.inflate(R.layout.newnotenewattachment, newnotewindowextras, false);
newnotewindowextras.addView(newnoteattachment_window);
//listview for attachment files
attachmentsListView = (ListView) newnoteattachment_window.findViewById(R.id.attachmentsListView);
String attachmentName = "My test file ";
String attachmentDateAdded = "Added: Nov ";
//create random data
for (int i = 0; i < 3; i++) {
HashMap<String, Object> singleAttachment = new HashMap<String, Object>();
singleAttachment.put(KEY_ATTACHMENT_NAME, attachmentName + i);
singleAttachment.put(KEY_ATTACHMENT_DATE_ADDED, attachmentDateAdded + (i + 1));
attachmentsListArray.add(singleAttachment);
}
String[] keys = {KEY_ATTACHMENT_NAME, KEY_ATTACHMENT_DATE_ADDED};
int[] ids = {R.id.attachment_name, R.id.attachment_date_added};
simpleAdapter = new SimpleAdapter(getActivity().getApplicationContext(), attachmentsListArray, R.layout.individualattachmentlayout, keys, ids);
attachmentsListView.setAdapter(simpleAdapter);
//the actual action for this button
Intent openFileExplorerIntent = new Intent(Intent.ACTION_GET_CONTENT);
openFileExplorerIntent.setType("*/*");
getActivity().startActivityForResult(openFileExplorerIntent, Integer.parseInt(NEW_NOTE_CARD_FRAGMENT_CODE + PICK_FILE_REQ_CODE));
}
});
return v;
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
int reqCode_l = Character.getNumericValue(Integer.toString(requestCode).charAt(1));
if (reqCode_l == Integer.parseInt(PICK_FILE_REQ_CODE)) {//do file pick stuff
//new individual file window
Log.i("MENU ACTION", "FILE PICK: " + data.getData());
String attachmentName = "Title ";
String attachmentDateAdded = "Edited: Nov ";
for (int i = 0; i < 6; i++) {
HashMap<String, Object> singleAttachment = new HashMap<String, Object>();
singleAttachment.put(KEY_ATTACHMENT_NAME, attachmentName + (i+1));
singleAttachment.put(KEY_ATTACHMENT_DATE_ADDED, attachmentDateAdded + (i + 1));
//singleAttachment.put(KEY_ATTACHMENT_ICON, tmp_attachmentIcon);
attachmentsListArray.add(singleAttachment);
}
simpleAdapter.notifyDataSetChanged();
}
}
}
我在这里看到的一个大问题是在startActivityOnResult完成后我们回到对话框的活动中，变量设置为null，我初始化按钮点击。
NEW UPDATE
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
Log.i("LIFECYCLE", "onCreate");
}
@Override
public void onDestroyView() {
Log.i("LIFECYCLE", "Fragment onDestroyView");
if (getDialog() != null && getRetainInstance())
getDialog().setDismissMessage(null);
super.onDestroyView();
}
同样，当startActivtiyForResult被调用时onPause()和onStop()，但onDestroyView()永远不会被调用。
它仍然无法运作。
最终更新
我想为我正在做的愚蠢的高度道歉。在我Activity的托管MainActivity.java中，当Activity调用onActivityResult()时，我会创建一个对话框片段的新实例：new MyDialogFragment().onActivityResult()这就是为什么你们这些人的方法都没有工作的原因onCreateView这次没有被调用。我已将new MyDialogFragment()更改为我实际显示的先前初始化的对话框片段，现在一切正常。我将结束这个问题。
答案 0 :(得分：1)
<强>更新
如果DialogFragment没有添加到后台堆栈，那么您可以在第一次创建时尝试使用 setRetainInstance (boolean retain)。
原始回答
我认为您需要稍微修改一下程序流程。
简而言之，您应该为数据设置ListView，ArrayList，并在onActivityCreated设置Adapter。
这样，在您的用户可以从DialogFragment中选择一个文件之前，您将准备好ListView及其适配器以接收新数据。
然后在onActivityResult块中，只需将数据添加到ArrayList并在适配器上调用notifyDatasetChanged。
答案 1 :(得分：0)
ohkay试试这个，先生..假设你的活动课是Gurinderhans;
static Gurinderhans ellt; // lol
然后仍在您的活动课程中。
static Gurinderhans getGurinderhans(){
return ellt;
}
然后在你的活动onCreate（）
Gurinderhans.ellt = this; //or ellt = this;
然后在你的dialogfragment onActivityResult中执行此操作
Gurinderhans.getGurinderhans() // this is my class, activity and context..
所以看起来应该是这样的
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
...
//here I want to get the context
SimpleAdapter simpleAdapter = new SimpleAdapter(Gurinderhans.getGurinderhans(), attachments_list, R.layout.mycustomlayout, keys, ids);
...
}
如果有帮助，请告诉我..