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android - 回收站视图不显示项目

问题描述

我一直在制作一个使用 RecyclerView 但它没有显示任何东西的应用程序。为什么没有显示回收器视图的内容。我的代码如下

activity_history.xml

<LinearLayout
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=".HistoryActivity"
android:fitsSystemWindows="true"
android:orientation="vertical"
android:id="@+id/layout">

<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v7.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/historyRecyclerView"
        android:scrollbars="vertical">
    </android.support.v7.widget.RecyclerView>

</android.support.v4.widget.NestedScrollView>

HistoryActivity.java

public class HistoryActivity extends AppCompatActivity {
private RecyclerView mHistoryRecyclerView;
private RecyclerView.Adapter mHistoryAdapter;
private RecyclerView.LayoutManager mHistoryLayoutManager;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_history);

    Toast.makeText(this, "dddd", Toast.LENGTH_SHORT).show();
    mHistoryRecyclerView = (RecyclerView) findViewById(R.id.historyRecyclerView);
    mHistoryRecyclerView.setNestedScrollingEnabled(false);
    mHistoryRecyclerView.setHasFixedSize(true);
    mHistoryLayoutManager = new LinearLayoutManager(HistoryActivity.this);
    mHistoryRecyclerView.setLayoutManager(mHistoryLayoutManager);
    mHistoryAdapter = new HistoryAdapter(getDataSetHistory(), HistoryActivity.this);
    mHistoryRecyclerView.setAdapter(mHistoryAdapter);

       HistoryObject obj=new HistoryObject("12345");
       resultsHistory.add(obj);

    mHistoryAdapter.notifyDataSetChanged();

}
private ArrayList resultsHistory = new ArrayList<HistoryObject>();
private List<HistoryObject> getDataSetHistory() {
    return resultsHistory;

}

}

HistoryAdapter.java

public class HistoryAdapter extends RecyclerView.Adapter<HistoryViewHolders> {
private List<HistoryObject> itemList;
private Context context;

public HistoryAdapter(List<HistoryObject> itemList, Context context) {

    this.itemList = itemList;
    this.context = context;
    Toast.makeText(context,itemList.size()+"" , Toast.LENGTH_SHORT).show();
}

@NonNull
@Override
public HistoryViewHolders onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View layoutView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_history, null, false);

    HistoryViewHolders rcv = new HistoryViewHolders(layoutView);
    return rcv;

}

@Override
public void onBindViewHolder(@NonNull HistoryViewHolders holder, int position) {
    holder.rideId.setText(itemList.get(position).getRideId());
    Toast.makeText(context, holder.rideId.getText().toString(), Toast.LENGTH_SHORT).show();

}

@Override
public int getItemCount() {
    return 0;
}

}

历史对象

    package com.example.ikramkhan.insta.historyRecyclerView;

public class HistoryObject {
    private String rideId;

    public HistoryObject(String rideId) {
        this.rideId = rideId;
    }

    public String getRideId() {
        return rideId;
    }
    public void setRideId(String rideId) {
        this.rideId = rideId;
    }
}

HistoryViewHolders.java

    public class HistoryViewHolders extends RecyclerView.ViewHolder implements View.OnClickListener{

    public TextView rideId;

    public HistoryViewHolders(View itemView) {
        super(itemView);
        itemView.setOnClickListener(this);
        rideId = (TextView) itemView.findViewById( R.id.rideId);
    }

    @Override
    public void onClick(View v) {

    }
}

标签： androidandroid-recyclerview

解决方案

您为 itemCount 返回零，因此您的适配器认为您没有任何项目。在你的适配器中试试这个：

@Override
public int getItemCount() {
    return itemList.size();
}

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