从 Activity AlertDialog 添加到 Fragment ArrayAdapter
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【中文标题】从 Activity AlertDialog 添加到 Fragment ArrayAdapter【英文标题】：Adding to Fragment ArrayAdapter from Activity AlertDialog 【发布时间】：2017-03-31 13:16:13 【问题描述】：我正在学习在 android Studio 中制作原型，但遇到了一个我似乎找不到任何答案的问题。
我有一个将自定义 ArrayAdapter 显示为 ListView 的 Activity。我可以通过单击它们并在生成的 AlertDialog 中键入来编辑 ListView 中的项目。还有一个我可以按下的添加按钮，它会弹出一个类似的 AlertDialog，但是当我点击保存时，没有任何内容会添加到 ListView。如何获取 AlertDialog 文本输入以另存为新的 ArrayAdapter 项？
我发现的大多数示例都是直接在 Activity 中实例化 ArrayAdapter，而不是像我那样通过 Fragment 实例化。
MainActivity.java
public class MainActivity extends AppCompatActivity
private static final String TAG = "MainActivity";
@Override
protected void onCreate(Bundle savedInstanceState) //initialize the activity
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); //establish where the layout will come from
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); //creates a toolbar
setSupportActionBar(toolbar);
if (findViewById(R.id.fragment_container) != null)
if (savedInstanceState != null)
return;
//creates the first fragment dynamically, so it can be replaced
Fragment firstFragment = new MainActivityFragment();
firstFragment.setArguments(getIntent().getExtras());
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, firstFragment).commit();
//This creates the Floating Action Button
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
createDialog();
private void createDialog()
ArrayList<User> users = new ArrayList<User>();
// create an AlertDialog that'll come up when the add button is clicked
AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);
// set title
alertDialog.setTitle("Add item");
final EditText input = new EditText(MainActivity.this); //uses the EditText from dialog_set
input.setInputType(InputType.TYPE_CLASS_TEXT); //makes the dialog ask for plain text input
alertDialog.setView(input);
// set up buttons
alertDialog.setPositiveButton("Save", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
String textInput = input.getText().toString(); //saves user text as a string
Log.d(TAG, textInput); // records input as a log
CustomUsersAdapter.this.add(textInput);
);
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
dialog.cancel();
);
// show it
alertDialog.show();
);
MainActivityFragment.java
public class MainActivityFragment extends Fragment
@BindView(R.id.lvUsers) ListView listView;
public MainActivityFragment()
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View view = inflater.inflate(R.layout.fragment_main, container, false);
ButterKnife.bind(this, view);
ArrayList<User> arrayOfUsers = new ArrayList<User>();
arrayOfUsers.add(new User("Person 1", "Hometown 1"));
arrayOfUsers.add(new User("Person 2", "Hometown 2"));
arrayOfUsers.add(new User("Person 3", "Hometown 3"));
arrayOfUsers.add(new User("Person 4", "Hometown 4"));
arrayOfUsers.add(new User("Person 5", "Hometown 5"));
// Create the adapter to convert the array to views
CustomUsersAdapter adapter = new CustomUsersAdapter(getContext(), arrayOfUsers);
// Attach the adapter to a ListView
listView.setAdapter(adapter);
return view;
CustomUsersAdapter.java
public class CustomUsersAdapter extends ArrayAdapter<User>
private ArrayList<User> users;
public CustomUsersAdapter(Context context, ArrayList<User> users)
super(context, 0, users);
this.users = users;
@Override
public View getView(final int position, View convertView, ViewGroup parent)
// Get the data item for this position
User user = getItem(position);
// Check if an existing view is being reused, otherwise inflate the view
if (convertView == null)
convertView = LayoutInflater.from(getContext()).inflate(R.layout.item_user, parent, false);
// Lookup view for data population
TextView tvName = (TextView) convertView.findViewById(R.id.tvName);
TextView tvHome = (TextView) convertView.findViewById(R.id.tvHometown);
// Populate the data into the template view using the data object
tvName.setText(user.name);
tvHome.setText(user.hometown);
convertView.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
createDialog(position);
);
// Return the completed view to render on screen
return convertView;
protected void add(String textInput)
add(new User(textInput, "Incomplete"));
private void createDialog(final int position)
// create an AlertDialog that'll come up when text is clicked
AlertDialog.Builder alertDialog = new AlertDialog.Builder(
getContext());
// set title
alertDialog.setTitle("Edit item");
final EditText input = new EditText(getContext()); //uses the EditText from dialog_set
input.setInputType(InputType.TYPE_CLASS_TEXT); //makes the dialog ask for plain text input
alertDialog.setView(input);
// set up buttons
alertDialog.setPositiveButton("Save", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
String textInput = input.getText().toString(); //saves user text as a string
users.get(position).name = textInput;
notifyDataSetChanged();
);
alertDialog.setNeutralButton("Complete", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
users.get(position).hometown = "Complete";
notifyDataSetChanged();
);
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
dialog.cancel();
);
// show it
alertDialog.show();
ListView 布局（来自 fragment_main.xml）
<ListView
android:id="@+id/lvUsers"
android:layout_
android:layout_
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true" >
</ListView>
【问题讨论】：
I can edit the items in the ArrayAdapter by clicking on them。不可能的。数组适配器没有 gui 元素，没有视图，因此无法点击。请改写。
你有 FAB 在 Activity 和 Fragment 中的原因吗？
@greenapps，我稍微改变了措辞 - 现在更清楚了吗？
@BlackHatSamurai，不是吗？它已经在活动中（我使用了已经包含 FAB 的模板），就像我说的，我正在学习，所以我一直在使用我可用的东西。将 FAB 移动到片段是否有用？
that displays a custom ArrayAdapter as an ArrayList. I can edit the items in the ArrayList by clicking on them。也是不可能的。数组列表是不可见的。它不是gui元素。这是没有意见。所以你不能点击它。请重试。
【参考方案1】：
您有几个问题。首先，您尝试使用静态调用更新您的适配器，但您不能这样做。您还需要调整您的add 方法。它应该类似于：
protected void add(String textInput)
this.users.add(new User(textInput, "Incomplete"));
这只是问题的一部分。您需要将对象引用传递给onClickListener。您正在尝试进行静态调用。这行不通。我可能会考虑放置浮动操作按钮。如果你这样做了，那么你可以轻松地将引用传递给适配器：
public class MainActivityFragment extends Fragment
private final CustomUsersAdapter adapter;
@BindView(R.id.lvUsers) ListView listView;
public MainActivityFragment()
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View view = inflater.inflate(R.layout.fragment_main, container, false);
ButterKnife.bind(this, view);
ArrayList<User> arrayOfUsers = new ArrayList<User>();
arrayOfUsers.add(new User("Person 1", "Hometown 1"));
arrayOfUsers.add(new User("Person 2", "Hometown 2"));
arrayOfUsers.add(new User("Person 3", "Hometown 3"));
arrayOfUsers.add(new User("Person 4", "Hometown 4"));
arrayOfUsers.add(new User("Person 5", "Hometown 5"));
// Create the adapter to convert the array to views
adapter = new CustomUsersAdapter(getContext(), arrayOfUsers);
// Attach the adapter to a ListView
listView.setAdapter(adapter);
return view;
//This creates the Floating Action Button
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View view)
createDialog();
private void createDialog()
ArrayList<User> users = new ArrayList<User>();
// create an AlertDialog that'll come up when the add button is clicked
AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);
// set title
alertDialog.setTitle("Add item");
final EditText input = new EditText(MainActivity.this); //uses the EditText from dialog_set
input.setInputType(InputType.TYPE_CLASS_TEXT); //makes the dialog ask for plain text input
alertDialog.setView(input);
// set up buttons
alertDialog.setPositiveButton("Save", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
String textInput = input.getText().toString(); //saves user text as a string
Log.d(TAG, textInput); // records input as a log
adapter.add(textInput);
);
alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener()
@Override
public void onClick(DialogInterface dialog, int which)
dialog.cancel();
);
// show it
alertDialog.show();
);
通过执行这样的操作，您可以将对适配器的引用传递到您创建的内部类中，然后对其进行更新。希望这可以帮助。
【讨论】：
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