Question

我有这个使用json api的工作代码，并在recyclerview中显示它们。我还添加了ItemTouchHelper以便滑动以删除操作。现在，我想显示有关新活动的已删除项目。我怎样才能做到这一点？谢谢...

我的MainActivity.java在下面：

public class MainActivity extends AppCompatActivity implements RecyclerItemTouchHelperListener {

private final String URL_API = "https://api.openbrewerydb.org/breweries";
private RecyclerView recyclerView;
private List<Item> list;
private CardListAdapter adapter;
private CoordinatorLayout rootLayout;

IMenuRequest mService;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mService = Common.getMenuRequest();

    Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setTitle("Breweries");
    getSupportActionBar().setDisplayHomeAsUpEnabled(false);

    recyclerView = (RecyclerView)findViewById(R.id.recycler_view);
    rootLayout = (CoordinatorLayout)findViewById(R.id.rootLayout);
    list = new ArrayList<>();
    adapter = new CardListAdapter(this,list);

    RecyclerView.LayoutManager layoutManager = new 
LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
    recyclerView.addItemDecoration(new DividerItemDecoration(this, 
DividerItemDecoration.VERTICAL));
    recyclerView.setAdapter(adapter);

    ItemTouchHelper.SimpleCallback itemTouchHelperCallBack
            =new RecyclerItemTouchHelper(0, ItemTouchHelper.LEFT, this);
    new 
ItemTouchHelper(itemTouchHelperCallBack).attachToRecyclerView(recyclerView);

    addItem();
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if(id == R.id.show_deleted) {
        Intent myintent = new Intent(MainActivity.this,
                NewActivity.class);
        startActivity(myintent);
        return false;
    }

    return super.onOptionsItemSelected(item);
}

private void addItem() {
    mService.getMenuList(URL_API)
            .enqueue(new Callback<List<Item>>() {
                @Override
                public void onResponse(Call<List<Item>> call, 
Response<List<Item>> response) {
                    list.clear();
                    list.addAll(response.body());
                    adapter.notifyDataSetChanged();
                }

                @Override
                public void onFailure(Call<List<Item>> call, Throwable t) {

                }
            });
}

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction, int 
position) {

    if(viewHolder instanceof CardListAdapter.MyViewHolder){
        String name = list.get(viewHolder.getAdapterPosition()).getName();

        final Item deletedItem = list.get(viewHolder.getAdapterPosition());
        final int deleteIndex = viewHolder.getAdapterPosition();

        adapter.removeItem(deleteIndex);

        Snackbar snackbar = Snackbar.make(rootLayout, name + " removed from 
list!", Snackbar.LENGTH_LONG);
        snackbar.setAction("UNDO", new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                adapter.restoreItem(deletedItem, deleteIndex);

            }
        });

        snackbar.setActionTextColor(Color.YELLOW);
        snackbar.show();
    }

}
}

Answer 1

您必须执行以下步骤：

1）首先，您必须像这样在Item类中实现Serializable

public class Item implements Serializable{
...
}

2）在onCreate方法上方定义一个像下面这样的数组列表。

private List<Item> removedItems;

3）在onCreate方法中，编写以下代码：

removedItems = new ArrayList<>();

3）在adapter.removeItem(deleteIndex)之后写下面的代码

removedItems.add(deletedItem);

4）在此代码adapter.restoreItem(deletedItem, deleteIndex)之后；写下面的代码

removedItems.remove(deletedItem);

5）在调用onOptionsItemSelected方法之前在startActivity方法中编写下面的代码

intent.putExtra("data", (ArrayList<Item>) removedItems);

6）在NewActivity中，您可以通过以下代码访问已删除列表：

ArrayList<Item> list =(ArrayList<Item>)getIntent().getSerializableExtra("data");

如何在新活动上显示已删除的项目？

1 个答案: