Question

我正在从主要活动中使用RecyclerView开始新活动。项目正确显示。但是在滚动上发生了一些奇怪的事情。项目未正确呈现。如果在主屏幕中，相同的RecyclerView可以正常工作。

主要活动：

public class MainActivity extends AppCompatActivity {

    ImageButton templatButton;

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

        templatButton = findViewById(R.id.template_button);
        templatButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                Intent myIntent = new Intent(getBaseContext(), NewActivity.class);
                startActivity(myIntent);
            }
        });
    }

}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageButton
        android:id="@+id/template_button"
        android:layout_width="180dp"
        android:layout_height="180dp"
        android:layout_marginStart="8dp"
        android:layout_marginBottom="28dp"
        android:background="@drawable/template_icon"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent" />

</android.support.constraint.ConstraintLayout>

新活动中的onCreate方法：

    public class NewActivity extends AppCompatActivity {
        RecyclerView recyclerView;

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

                // Initializing list view with the custom adapter
                ArrayList <Item> itemList = new ArrayList<Item>();

                ItemArrayAdapter itemArrayAdapter = new ItemArrayAdapter(R.layout.list_item, itemList);
                recyclerView = (RecyclerView) findViewById(R.id.item_list);
                recyclerView.setLayoutManager(new LinearLayoutManager(this));
                recyclerView.setItemAnimator(new DefaultItemAnimator());
                recyclerView.setAdapter(itemArrayAdapter);

                // Populating list items
                for(int i=0; i<100; i++) {
                    itemList.add(new Item("Item " + i));
                }

            }
}

项目阵列适配器：

public class ItemArrayAdapter extends RecyclerView.Adapter<ItemArrayAdapter.ViewHolder> {

    //All methods in this adapter are required for a bare minimum recyclerview adapter
    private int listItemLayout;
    private ArrayList<Item> itemList;
    // Constructor of the class
    public ItemArrayAdapter(int layoutId, ArrayList<Item> itemList) {
        listItemLayout = layoutId;
        this.itemList = itemList;
    }

    // get the size of the list
    @Override
    public int getItemCount() {
        return itemList == null ? 0 : itemList.size();
    }


    // specify the row layout file and click for each row
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(listItemLayout, parent, false);
        ViewHolder myViewHolder = new ViewHolder(view);
        return myViewHolder;
    }

    // load data in each row element
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
        TextView item = holder.item;
        item.setText(itemList.get(listPosition).getName());
    }

    // Static inner class to initialize the views of rows
    static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public TextView item;
        public ViewHolder(View itemView) {
            super(itemView);
            itemView.setOnClickListener(this);
            item = (TextView) itemView.findViewById(R.id.row_item);
        }
        @Override
        public void onClick(View view) {
            Log.d("onclick", "onClick " + getLayoutPosition() + " " + item.getText());
        }
    }
}

activitiy_list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
    <android.support.v7.widget.RecyclerView
        android:id="@+id/item_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical"
        />
</LinearLayout>

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/row_item"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:gravity="center"/>
</LinearLayout>

Answer 1

在填充列表项之后设置适配器

用以下代码粘贴将您 NewActivity.java 代码替换为该行之后 setContentView（R.layout.activity_list）;

        // Initializing list view with the custom adapter

            ArrayList <Item> itemList = new ArrayList<Item>();

            recyclerView = (RecyclerView) findViewById(R.id.item_list);
            recyclerView.setLayoutManager(new LinearLayoutManager(this));
            recyclerView.setItemAnimator(new DefaultItemAnimator());

            //Set Adapter Here
            ItemArrayAdapter itemArrayAdapter = new ItemArrayAdapter(R.layout.list_item, itemList);
            recyclerView.setAdapter(itemArrayAdapter);

            // Populating list items
            for(int i=0; i<100; i++) {
                itemList.add(new Item("Item " + i));
            }

快乐编码！

Answer 2

1）

之后通知您的适配器

  recyclerView.setAdapter(itemArrayAdapter);

  itemArrayAdapter.notifyDataSetChanged();

还要确保您的活动没有任何覆盖布局，请再次进行验证。 2）在活动开关上

 templatButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(getBaseContext(), NewActivity.class);
            startActivity(myIntent);
        }
    });

代替

 templatButton.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            Intent myIntent = new Intent(getApplicationContext(), NewActivity.class);
            startActivity(myIntent);
        }
    });

使用 getApplicationContext（） you can get more in detail here

RecyclerView绘图问题

2 个答案: