我在其中創建了一個菜單項 (Spinner).onCreateOptionsMenu并希望保留屏幕旋轉時的選擇。我知道使用 是常見的做法SharedPreferences，但是在這種情況下我有點困惑，因為我沒有在 中創建我的視圖.onCreate()，我通常會在那里加載我保存的首選項： @Overridepublic boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.action_bar_spinner, menu); MenuItem item = menu.findItem(R.id.spinner); mSpinner = (Spinner) item.getActionView(); int selectedPosition = mPrefs.getInt(SPINNER_SELECTION, 0); mSpinner.setSelection(selectedPosition); if (isOnline()) { ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(getApplicationContext(), R.array.spiner_list_item_array, R.layout.custom_spinner); adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); mSpinner.setAdapter(adapter); mSpinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { @Override public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) { mPrefsEditor.putInt(SPINNER_SELECTION, i); mPrefsEditor.commit(); switch (i) { case 0: mBaseURL = "https://api.themoviedb.org/3/movie/popular/"; calltoRetrofit(mBaseURL); break; case 1: mBaseURL = "https://api.themoviedb.org/3/movie/top_rated/"; calltoRetrofit(mBaseURL); break; case 2: mIsFavoriteSelected = true; mMovieURLS.clear(); retrieveMovies(); break; default: mBaseURL = "https://api.themoviedb.org/3/movie/popular/"; break; } }
1 回答
隔江千里
TA貢獻1906條經驗 獲得超10個贊
首先，以onCreate.以外的其他方法訪問 SharedPreferences 是完全有效的。如果您在這篇文章中遇到一些問題，請查看錯誤消息/問題。
其次，為了在屏幕旋轉時保留內容，您可以onSaveInstanceState在 Activity 中使用 來保存微調器選擇并onCreate在屏幕旋轉時獲得狀態。例如：
private int saved_selection = -1
@Override
protected void onCreate(Bundle savedInstanceState) {
//...
if (savedInstanceState != null) {
saved_selection = savedInstanceState.getInt("SPINNER_SELECTION");
}
//...
}
@Override
public void onSaveInstanceState(Bundle outState) {
outState.putInt("SPINNER_SELECTION", saved_selection);
// call superclass to save any view hierarchy
super.onSaveInstanceState(outState);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
//...
// set `saved_selection = i;` in your adapter
//...
if( saved_selection >= 0 ) {
mSpinner.setSelection(saved_selection);
}
}
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