如何保存有用户添加和删除到RecyclerView的项目?Android

Question

我已经开始与材料设计工作，第一次见到它。我这里需要帮助。从RecyclerView中添加和删除项目正在工作，但我想保存该条件。谢谢你。

下面是我的代码:

public class MainActivity extends BaseActivity {
//int containing the duration of the animation run when items are added or removed from the RecyclerView
public static final int ANIMATION_DURATION = 2000;
//edit text letting the user type item name to be added to the recylcerview
private EditText mInput;
//recyclerview showing all items added by the user
private RecyclerView mRecyclerView;
private AdapterRecyclerAnimators mAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    initViews();

}
private void initViews(){
    mInput = (EditText) findViewById(R.id.text_input);
    mRecyclerView = (RecyclerView) findViewById(R.id.recyclerAnimatedItems);
    mAdapter = new AdapterRecyclerAnimators(this);
    //set an animator on the RecyclerView that works only when items are added or removed
    mRecyclerView.setItemAnimator(new SlideInLeftAnimator());
    mRecyclerView.getItemAnimator().setAddDuration(ANIMATION_DURATION);
    mRecyclerView.getItemAnimator().setRemoveDuration(ANIMATION_DURATION);
    mRecyclerView.setAdapter(mAdapter);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
}
public void addItem(View view) {
    //check if the EditText has valid contents
    if (Util.hasValidContents(mInput)) {
        mAdapter.addItem(mInput.getText().toString());
    }
}
@Override
protected int getLayoutResourceId() {
    return R.layout.activity_main;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();
    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }
    return super.onOptionsItemSelected(item);
}
}

这是一个适配器

    public class AdapterRecyclerAnimators extends RecyclerView.Adapter<AdapterRecyclerAnimators.Holder> {
    private ArrayList<String> mListData = new ArrayList<>();
    private LayoutInflater mLayoutInflater;

    public AdapterRecyclerAnimators(Context context) {
        mLayoutInflater = LayoutInflater.from(context);
    }

    @Override
    public Holder onCreateViewHolder(ViewGroup parent, int viewType) {
        View row = mLayoutInflater.inflate(R.layout.custom_row_item, parent, false);
        Holder holder = new Holder(row);
        return holder;
    }
    @Override
    public void onBindViewHolder(Holder holder, final int position) {
        String data = mListData.get(position);
        holder.textDataItem.setText(data);
        holder.buttonDelete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                removeItem(position);
            }
        });
    }
    public void addItem(String item) {
        mListData.add(item);
        notifyItemInserted(mListData.size());
    }
    public void removeItem(String item) {
        int position = mListData.indexOf(item);
        if (position != -1) {
            mListData.remove(item);
            notifyItemRemoved(position);
        }
    }
    public void removeItem(int position) {
        mListData.remove(position);
        notifyItemRemoved(position);
    }
    @Override
    public int getItemCount() {
        return mListData.size();
    }
    public static class Holder extends RecyclerView.ViewHolder {
        TextView textDataItem;
        ImageButton buttonDelete;
        public Holder(View itemView) {
            super(itemView);
            textDataItem = (TextView) itemView.findViewById(R.id.text_item);
            buttonDelete = (ImageButton) itemView.findViewById(R.id.button_delete);
        }
    }
}

Answer 1

要保存你的项目，在你的活动中使用:

@Override
public void onSaveInstanceState(Bundle outState) {
    outState.putStringArrayList("items", itemList);
}

在OnCreate:

if(savedInstanceState != null){
    ArrayList<String> items = savedInstanceState.getStringArrayList("items");
    itemList.addAll(items);
    adapter.notifyDataSetChanged();
}