[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)。 它被声明为public static,所以我可以在ActivityNewGame中访问它。 我的问题是,当我启动应用程序并直接转到该ActivityNewGame时,在我访问ActivityPlayers之前,它不会渲染该数组列表(必须从字面上打开它),之后,它会在ActivityNewGame中完美地渲染该列表。整个会话之前,我再次关闭该应用程序。 有任何想法为什么会这样,或者我该怎么办? 这个程序是我自己的项目,它没有敏感数据,因此“丑陋”的解决方案也很好,只要它不会显示给用户即可。
这是我的ActivityPlayers,addItem()插入新名称并将其保存到列表中
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();
}
这是我的ActivityNewGame,insertNames()从ActivityPlayers中获取该Arraylist,并将其名称插入recyclerview项中。
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()));
}
}
}
这是由于ActivityPlayers中的mNamelist为空
mNamelist中的数据传递位于ActivityNewGame中,因此您必须传递ActivityNewGame中的数据以呈现arrayList
这是我的建议,没有看到代码。 但是我认为这对您有效,您可能会理解。
在打开ActivityPlayer
之前,您基本上不会初始化mNameList
。 您需要做的就是初始化ActivityNewGame
的值。
将您的loadData()
更改为静态函数,然后在ActivityNewGame
onCreate()
中首先调用它。
编辑 -
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();
}
}
只需根据需要在onCreate
调用loadData(this)
。
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