Question

有人可以编辑此代码吗？这不会显示任何带有recyclerview的项目哪里错了？可以给我编辑的例子吗？或指示我错在哪里。

MainActivity.java

package com.numetriclabz.recyclerviewwithsearch;

import android.content.Context;
import android.os.Handler;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.SearchView;

import org.json.JSONArray;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    public SearchView search;
    Adapter mAdapter;
    protected Handler handler;


    private List<Actors> list = new ArrayList<Actors>();



    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        RecyclerView mRecyclerView = (RecyclerView)   findViewById(R.id.recyclerview);

        List<Actors> data = createlist();  // in this method, Create a list of items.

        mRecyclerView.setHasFixedSize(true);

        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));


        mAdapter = new Adapter(data, getApplication(), mRecyclerView );

        mRecyclerView.setAdapter(mAdapter);

        handler = new Handler();


        mAdapter.setOnLoadMoreListener(new Adapter.OnLoadMoreListener() {

            @Override
            public void onLoadMore() {

                //add progress item
                list.add(null);

                mAdapter.notifyItemInserted(list.size() - 1);


                handler.postDelayed(new Runnable() {

                    @Override
                    public void run() {

                        //remove progress item
                        list.remove(list.size() - 1);

                        mAdapter.notifyItemRemoved(list.size());

                        //add items one by one
                        for (int i = 0; i < 15; i++) {

                            list.add(new Actors("b" + (list.size() + 1)));

                            mAdapter.notifyItemInserted(list.size());

                        }

                        mAdapter.setLoaded();
                        //or you can add all at once but do not forget to call mAdapter.notifyDataSetChanged();
                    }

                }, 2000);

                System.out.println("load");

            }

        });


   }

    // this method is used to create list of items.
    public List<Actors> createlist(){

        List<Actors> data = new ArrayList<>();

        for(int i=1; i<=12;i++) {

            list.add(new Actors("a"+i));
        }

        return data;
    }

}

Adapter.java

package com.numetriclabz.recyclerviewwithsearch;


import android.content.Context;
import android.provider.ContactsContract;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import java.util.Collections;
import java.util.List;


public class Adapter extends RecyclerView.Adapter<View_Holder> {



    private List<Actors> mDataset = Collections.emptyList();

    // The minimum amount of items to have below your current scroll position before loading more.
    private int visibleThreshold = 2;
    private int lastVisibleItem, totalItemCount;
    private boolean loading;
    private OnLoadMoreListener onLoadMoreListener;


    protected Context context;


    public Adapter(List<Actors> myDataSet, Context context, RecyclerView recyclerView) {
        this.mDataset = myDataSet;
        this.context = context;

        if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {

             final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();

             recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

                 @Override
                 public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

                     super.onScrolled(recyclerView, dx, dy);

                     totalItemCount = linearLayoutManager.getItemCount();
                     lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();

                    if (!loading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                        // End has been reached
                        // Do something

                        if (onLoadMoreListener != null) {
                            onLoadMoreListener.onLoadMore();
                        }

                        loading = true;

                    }

                }

            });

        }

    }




     @Override
     public View_Holder onCreateViewHolder(ViewGroup parent, int viewType) {

         View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.row_layout, parent, false);
         View_Holder holder = new View_Holder(v);

         return holder;
     }


    @Override
    public void onBindViewHolder(View_Holder holder, int position) {

        holder.title.setText(mDataset.get(position).name);

    }




    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
    }

    // Insert a new item to the RecyclerView
    public void insert(int position, Actors data) {
        mDataset.add(position, data);
        notifyItemInserted(position);
    }
    // Remove a RecyclerView item containing the Data object
    public void remove(Actors data) {
        int position = mDataset.indexOf(data);
        mDataset.remove(position);
        notifyItemRemoved(position);
    }




    public void setLoaded() {

       loading = false;

    }


    @Override
    public int getItemCount() {

        return mDataset.size();

    }

     public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {

        this.onLoadMoreListener = onLoadMoreListener;

    }

    public interface OnLoadMoreListener {

        void onLoadMore();

    }

    public static class TextViewHolder extends RecyclerView.ViewHolder {

        public TextView mTextView;

        public TextViewHolder(View v) {

            super(v);
            mTextView = (TextView) v.findViewById(android.R.id.text1);

        }
    }

    public static class ProgressViewHolder extends RecyclerView.ViewHolder {

        public ProgressBar progressBar;

        public ProgressViewHolder(View v) {

            super(v);
            progressBar = (ProgressBar) v.findViewById(R.id.progressBar);

        }
    }
}

Actors.java

package com.numetriclabz.recyclerviewwithsearch;

public class Actors {

    public String name;


    Actors(String name) {

        this.name = name;
    }


}

View_Holder.java

package com.numetriclabz.recyclerviewwithsearch;

import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.TextView;


public class View_Holder extends RecyclerView.ViewHolder {

    CardView cv;
    TextView title;

        View_Holder(View itemView) {
        super(itemView);

        cv = (CardView) itemView.findViewById(R.id.cardView);
        title = (TextView) itemView.findViewById(R.id.title);
    }

}

OnLoadMoreListener.java

package com.numetriclabz.recyclerviewwithsearch;


public interface OnLoadMoreListener {
    void onLoadMore();
}

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.numetriclabz.recyclerviewwithsearch.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="10dp"
        android:layout_marginTop="8dp"/>

</RelativeLayout>

row_layout.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">


    <android.support.v7.widget.CardView
        android:id="@+id/cardView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">


        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TextView
                android:id="@+id/title"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                />

        </RelativeLayout>


    </android.support.v7.widget.CardView>

</LinearLayout>

progressbar_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <ProgressBar
        android:id="@+id/progressBar"
        android:layout_width="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_height="wrap_content" />

</LinearLayout>

Answer 1

你在这里做错了

public List<Actors> createlist(){

    List<Actors> data = new ArrayList<>();

    for(int i=1; i<=12;i++) {

        list.add(new Actors("a"+i));
    }

    return data;
}

此处list.add(new Actors("a"+i));您要在list对象中添加数据，但在return语句中，return data;表示您的data列表为空。所以改变它

 for(int i=1; i<=12;i++) {

      data.add(new Actors("a"+i));
 }

或将return data;更改为return list;

Answer 2

在MainActivity

中使用新的LinearLayoutManager（this）进行简单替换

new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false);

怎么编辑？此recyclerview不显示项目

2 个答案: