java - 在访问其他 Activity 之前， Activity 不会渲染数组列表

Question

我在 ActivityPlayers 中有 Arraylist(mNamelist)。它已被声明为公共(public)静态，因此我可以在 ActivityNewGame 中访问它。我的问题是，当我启动我的应用程序并直接进入 ActivityNewGame 时，在我访问 ActivityPlayers 之前(我必须打开它)，它不会渲染该数组列表，之后它会在 ActivityNewGame 中完美渲染该列表在我再次关闭应用程序之前的整个 session 。任何想法为什么会这样，或者我能做什么？这个应用程序是我自己的项目，它没有任何敏感数据，因此“丑陋”的解决方案也可以，只要它不会向用户显示即可。

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 获取该 Arraylist 并将其名称插入到 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()));
            }
        }
    }

Answer 1

在 ActivityPlayer 打开之前，您基本上不会初始化 mNameList。您所需要做的就是初始化 ActivityNewGame 中的值。

将您的 loadData() 更改为静态函数，并首先在 ActivityNewGame 的 onCreate() 中调用它。

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 中调用 loadData(this) 即可。