如何在Android MVVM架构中实现对话框选择选项 _如何在

壮心未与年俱老，死去犹能作鬼雄。这篇文章主要讲述如何在Android MVVM架构中实现对话框选择选项相关的知识，希望能为你提供帮助。
我正试图进入MVVM模式，我的问题是我不确定我是否正确使用它。 View负责所有UI操作（比如show stuff？）但是当我们需要在逻辑中改变某些东西时会发生什么。
所以我真正想做的是，显示一个包含某些选项的对话框，选择一个并重新加载应用程序。
我已经实现了MainActivity类中的函数，并且在需要操作时使用mCountrySelection.show（）。

public void createCountriesDialog() { AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(MainActivity.this); dialogBuilder.setTitle("Available Countries"); GridView gridView = new GridView(MainActivity.this); final String[] countries = getResources().getStringArray(R.array.countries); final String[] codes = getResources().getStringArray(R.array.codes); ArrayAdapter< String> arrayAdapter = new ArrayAdapter< > (getApplicationContext(), android.R.layout.simple_list_item_1, countries); gridView.setAdapter(arrayAdapter); dialogBuilder.setView(gridView); dialogBuilder.setNegativeButton("Close", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); } }); mCountrySelection = dialogBuilder.create(); gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView< ?> parent, View view, int position, long id) { PreferencesManager.setCountry(countries[position], codes[position]); getSupportActionBar().setTitle(PreferencesManager.getCountry()); FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); fragmentTransaction.replace(R.id.a_main_frame, new ArticlesFragment(), "ArticlesFragment"); fragmentTransaction.commit(); mCountrySelection.dismiss(); } }); }public void createAboutDialog() { AlertDialog.Builder aboutBuilder = new AlertDialog.Builder(MainActivity.this); aboutBuilder.setTitle("Top News v1.0"); aboutBuilder.setMessage("Simple application for displaying Top Headlines from newsapi.org.Icons made by Freepik from www.flaticon.com."); aboutBuilder.setNegativeButton("Close", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { dialog.dismiss(); } }); mAbout = aboutBuilder.create(); }

答案创建1个接口ItemClick并从您调用Dialog的位置实现此接口。

public interface ItemClick{ public void onClick(int position, String country); }

将此接口引用传递给对话框方法

public void createCountriesDialog(ItemClick listner) { AlertDialog.Builder dialogBuilder = new AlertDialog.Builder(MainActivity.this); dialogBuilder.setTitle("Available Countries"); GridView gridView = new GridView(MainActivity.this); final String[] countries = getResources().getStringArray(R.array.countries); final String[] codes = getResources().getStringArray(R.array.codes); ArrayAdapter< String> arrayAdapter = new ArrayAdapter< > (getApplicationContext(), android.R.layout.simple_list_item_1, countries); gridView.setAdapter(arrayAdapter); dialogBuilder.setView(gridView); dialogBuilder.setNegativeButton("Close", new DialogInterface.OnClickListener() { @Override public void onClick(DialogInterface dialog, int which) { dialog.dismiss(); listener = null; } }); mCountrySelection = dialogBuilder.create(); gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView< ?> parent, View view, int position, long id) { listener.onclick(position, countries[position]); PreferencesManager.setCountry(countries[position], codes[position]); getSupportActionBar().setTitle(PreferencesManager.getCountry()); FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); fragmentTransaction.replace(R.id.a_main_frame, new ArticlesFragment(), "ArticlesFragment"); fragmentTransaction.commit(); mCountrySelection.dismiss(); } }); }

然后，当您单击网格项时，使用接口引用调用onclick方法现在，当您将在onClick（int pos，String country）中收到回调时
使用您的视图模型进行api调用和重新加载屏幕。
在对话框关闭时设置listener = null以避免内存泄漏
另一答案1-在你的LiveData中暴露一个可变的Observer或ViewModel

public MutableLiveData< Pair< String, String> > countryInfo = new MutableLiveData< > ()

2-将用户选择传递给ViewModel

@Override public void onItemClick(AdapterView< ?> parent, View view, int position, long id) { viewModel.countryInfo.setValue(new Pair(countries[position], codes[position])) mCountrySelection.dismiss(); }

3-在ViewModel中运行用例（业务逻辑）（将信息上传到服务器，将其保存在数据库中等）
4-通过暴露另一个View更新Observable（在这种情况下相同的countryInfo将起作用）在MainActivity中观察countryInfo：

viewmodel.countryInfo.observe(this, new Observer< String> () { @Override public void onChanged(@Nullable final String newName) { // Update the UI PreferencesManager.setCountry(countries[position], codes[position]); getSupportActionBar().setTitle(PreferencesManager.getCountry()); getSupportFragmentManager().beginTransaction(); .replace(R.id.a_main_frame, new ArticlesFragment(), "ArticlesFragment"); .commit(); } });

【如何在Android MVVM架构中实现对话框选择选项】P.S：最好将此行移至ViewModel，因为它包含业务逻辑的一部分：