[英]How to send arraylist from activity to another, without visiting that other activity
[英]Activity won't render arraylist before visiting other activity
我在ActivityPlayers中有Arraylist(mNamelist)。 它被聲明為public static,所以我可以在ActivityNewGame中訪問它。 我的問題是,當我啟動應用程序並直接轉到該ActivityNewGame時,在我訪問ActivityPlayers之前,它不會渲染該數組列表(必須從字面上打開它),之后,它會在ActivityNewGame中完美地渲染該列表。整個會話之前,我再次關閉該應用程序。 有任何想法為什么會這樣,或者我該怎么辦? 這個程序是我自己的項目,它沒有敏感數據,因此“丑陋”的解決方案也很好,只要它不會顯示給用戶即可。
這是我的ActivityPlayers,addItem()插入新名稱並將其保存到列表中
public class ActivityPlayers extends AppCompatActivity {
public static ArrayList<NameItem> mNameList;
private RecyclerView mRecyclerViewPlayers;
private NameAdapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private Button buttonAdd;
private EditText textAdd;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_players);
loadData();
buildRecyclerView();
setButtons();
}
private void saveData() {
/** save data to shared pref **/
SharedPreferences prefs = getSharedPreferences("shared preference", Context.MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
try {
editor.putString("SharedPrefKey", ObjectSerializer.serialize(mNameList));
} catch (IOException e) {
e.printStackTrace();
}
editor.commit();
}
private void loadData() {
if (mNameList == null) {
mNameList = new ArrayList<>();
}
SharedPreferences prefs = getSharedPreferences("shared preference", Context.MODE_PRIVATE);
try {
mNameList = (ArrayList<NameItem>) ObjectSerializer.deserialize(prefs.getString("SharedPrefKey", ObjectSerializer.serialize(new ArrayList<NameItem>())));
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
private void addItem(int position) {
/** Get user input (name) **/
textAdd = findViewById(R.id.name_input);
/** Add name to the list **/
mNameList.add(position, new NameItem(textAdd.getText().toString().trim()));
/** sort that list **/
sortArrayList();
/** Save to shared pref **/
saveData();
/** Show changed list to user **/
mAdapter.notifyItemInserted(position);
/** Clear the input field **/
textAdd.getText().clear();
}
這是我的ActivityNewGame,insertNames()從ActivityPlayers中獲取該Arraylist,並將其名稱插入recyclerview項中。
public class ActivityNewGame extends AppCompatActivity {
private ArrayList<NewGamePlayerItem> mPlayerList;
private RecyclerView mRecyclerView;
private NewGamePlayerAdapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_new_game);
insertNames();
buildRecyclerView();
}
private void insertNames() {
if (ActivityPlayers.mNameList == null) {
mPlayerList = new ArrayList<>();
} else {
mPlayerList = new ArrayList<>();
for (int i = 0; i < ActivityPlayers.mNameList.size(); i++) {
/** false here is for my checkbox, which is in the item **/
mPlayerList.add(new NewGamePlayerItem(false, ActivityPlayers.mNameList.get(i).getText1()));
}
}
}
這是由於ActivityPlayers中的mNamelist為空
mNamelist中的數據傳遞位於ActivityNewGame中,因此您必須傳遞ActivityNewGame中的數據以呈現arrayList
這是我的建議,沒有看到代碼。 但是我認為這對您有效,您可能會理解。
在打開ActivityPlayer
之前,您基本上不會初始化mNameList
。 您需要做的就是初始化ActivityNewGame
的值。
將您的loadData()
更改為靜態函數,然后在ActivityNewGame
onCreate()
中首先調用它。
編輯 -
public void loadData(Context context) {
if (mNameList == null) {
mNameList = new ArrayList<>();
}
//SharedPreferences prefs = getApplicationContext().getSharedPreferences("shared preference", Context.MODE_PRIVATE);
SharedPreferences prefs = context.getSharedPreferences("shared preference", Context.MODE_PRIVATE);
try {
mNameList = (ArrayList<NameItem>) ObjectSerializer.deserialize(prefs.getString("SharedPrefKey", ObjectSerializer.serialize(new ArrayList<NameItem>())));
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
只需根據需要在onCreate
調用loadData(this)
。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.