RecyclerViewAdapter 的 onBindViewHolder() 方法出错

Question

伙计们，它可能看起来与您类似，就像其他 NullPionterException 问题一样，在将其标记为重复之前，请阅读它并尝试先理解我的问题并指出我错的地方。

实际上我的应用程序正在访问一些 JOSN 数据然后解析它并创建一个 POJO 对象并将该对象放入一些 ArrayList<SchemesHitsPojoModel> schemesListHitsWise 然后我将这个 ArrayList 发送到我的 RecyclerViewAdapter Class 然后将它显示在回收视图。

但是在我的 onBindViewHolder 方法中，当我尝试在 schemeName 上设置一些文本时，它给了我以下错误。帮助我，我最近几天试图解决这个问题并阅读了很多答案，但仍然存在这个错误。

LogCat

 java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
            at com.dovezeal.gapp.adapters.HitsOnSchemesDataDisplayAdapter.onBindViewHolder(HitsOnSchemesDataDisplayAdapter.java:71)
            at com.dovezeal.gapp.adapters.HitsOnSchemesDataDisplayAdapter.onBindViewHolder(HitsOnSchemesDataDisplayAdapter.java:21)
            at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5277)
            at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5310)
            at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4568)
            at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4461)
            at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1962)
            at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1371)
            at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1334)
            at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:563)
            at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2847)
            at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3145)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
            at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
            at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:579)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:514)
            at android.view.View.layout(View.java:15671)
            at android.view.ViewGroup.layout(ViewGroup.java:5038)
            at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2086)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1843)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1061)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5885)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
            at android.view.Choreographer.doCallbacks(Choreographer.java:580)
            at android.view.Choreographer.doFrame(Choreographer.java:550)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
            at android.os.Handler.handleCallback(Handler.java:739)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at c

MyAdapter 文件

 @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = null;
        MyViewHolder viewHolder;
        switch (success){
            case(0):
                view = layoutInflater.inflate(R.layout.custom_no_record_found_msg_screen, parent, false);
                break;
            case(1):
                view = layoutInflater.inflate(R.layout.custom_recyclerview_row_each_scheme_hits, parent,false);

        }
        viewHolder = new MyViewHolder(view);
        return viewHolder;
    }

@Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        SchemesHitsPojoModel firstObject = schemesListHitsWise.get(0);
        success = firstObject.getSuccess();
        if(success == 0 ){
            Log.d("SORRY!, "," We don't have any records to show you.");
        }
        else{
            SchemesHitsPojoModel currentSchemeRow =  schemesListHitsWise.get(position);
            holder.schemeName.setText(currentSchemeRow.getSchemeName());
            int langId = currentSchemeRow.getLanguage_id();
            switch(langId){
                case(1):
                    holder.languageName.setText("Punjabi");
                    break;
                case(2):
                    holder.languageName.setText("English");
            }

            holder.schemeViewDate.setText(currentSchemeRow.getSchemeViewDate());
            holder.schemeHits.setText(String.valueOf(currentSchemeRow.getSchemeHits()));
            holder.viewIcon.setImageResource(R.drawable.ic_remove_red_eye_black_18dp);
            //holder.totalHitsOnThisScheme.setText(currentSchemeRow.getSchemeTotalHitsCount());
        }
    }

// MyViewHolder
    public class MyViewHolder extends RecyclerView.ViewHolder{
        TextView schemeName, schemeViewDate, languageName, schemeHits,totalHitsOnThisScheme;
        ImageView viewIcon;

        public MyViewHolder(View itemView) {
            super(itemView);
            schemeName = (TextView) itemView.findViewById(R.id.hitsOnSchemeName);
            languageName = (TextView) itemView.findViewById(R.id.hitsOnLangName);
            viewIcon = (ImageView) itemView.findViewById(R.id.hitsOnViewIcon);
            schemeViewDate = (TextView) itemView.findViewById(R.id.hitsOnSchemeViewDate);
            schemeHits = (TextView) itemView.findViewById(R.id.hitsOnSchemeHits);
            //totalHitsOnThisScheme = (TextView) itemView.findViewById(R.id.totalHitsOnThisScheme);
        }
    }

XML RecyclerView自定义行文件

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp">


    <GridLayout
        android:id="@+id/gridLayout4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="10dp">

        <TextView
            android:id="@+id/hitsOnSchemeName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="0"
            android:layout_row="0"
            android:width="270dp"
            android:text="Name of the Scheme"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:textColor="#000"
            android:textSize="14dp" />

        <ImageView
            android:id="@+id/hitsOnViewIcon"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="1"
            android:layout_row="0"
            android:src="@drawable/ic_remove_red_eye_black_18dp" />

        <TextView
            android:id="@+id/hitsOnSchemeHits"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="2"
            android:layout_gravity="left|center"
            android:layout_marginLeft="3dp"
            android:layout_row="0"
            android:text="5"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:textSize="12dp" />

        <TextView
            android:id="@+id/hitsOnLangName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="0"
            android:layout_row="1"
            android:width="270dp"
            android:text="Language of scheme"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:textSize="10dp" />

        <TextView
            android:id="@+id/hitsOnSchemeViewDate"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_column="1"
            android:layout_columnSpan="2"
            android:layout_row="1"
            android:text="1989-12-09"
            android:textAppearance="?android:attr/textAppearanceSmall"
            android:textSize="12dp" />
    </GridLayout>

</RelativeLayout>

Answer 1

我想你的问题就在这里

holder.schemeName.setText(currentSchemeRow.getSchemeName());

将此更改为

holder.schemeName.setText(currentSchemeRow.get(position).getSchemeName());

移动

SchemesHitsPojoModel currentSchemeRow =  schemesListHitsWise.get(position);

出于else方法

Answer 2

你需要改变，

有两次机会得到这个错误。

1.Change 你的

holder.schemeViewDate.setText(currentSchemeRow.getSchemeViewDate());
holder.schemeHits.setText(String.valueOf(currentSchemeRow.getSchemeHits()));

到

   holder.schemeViewDate.setText(currentSchemeRow.get(position).getSchemeViewDate());
   holder.schemeHits.setText("" + currentSchemeRow..get(position).getSchemeHits());

currentSchemeRow 应该是您已获取和设置数据的模型的 Arraylist， 并且您必须从 get(position) 那是你选择的位置。

可能使用了错误的 ID，或者没有从两个布局文件中声明任何 custom_recyclerview_row_each_scheme_hits 或 custom_no_record_found_msg_screen

schemeName = (TextView) itemView.findViewById(R.id.hitsOnSchemeName);    
 languageName = (TextView) itemView.findViewById(R.id.hitsOnLangName);    
 viewIcon = (ImageView) itemView.findViewById(R.id.hitsOnViewIcon);    
 schemeViewDate=(TextView)itemView.findViewById(R.id.hitsOnSchemeViewDate); 
 schemeHits = (TextView) itemView.findViewById(R.id.hitsOnSchemeHits);

Answer 3

你的问题在 onCreateViewHolder

    switch (success){
        case(0):
            view = layoutInflater.inflate(R.layout.custom_no_record_found_msg_screen, parent, false);
            break;
        case(1):
            view = layoutInflater.inflate(R.layout.custom_recyclerview_row_each_scheme_hits, parent,false);

在这里你膨胀了两个不同的布局，所以你的所有 TexViews 必须存在于两个布局中。

或

在 onBindViewHolder 中放置一个 if 条件来处理空指针异常，因为在这两种情况下都必须调用 onBindViewHolder。

Answer 4

首先谢谢你们，我非常感谢你们的帮助。其实是我不好。

我将值存储到我的 onBindViewHolder() 中的 success 变量，这将用于两个方法（onCreateViewHolder(), onBindViewHolder() ），这是我的实际错误

因为我忘记了我在我的 onCreateViewHolder() 中使用这个 success 变量以及 select 我在特定情况下的特定布局，并且因为那个错误当我的 onCtreatViewHolder() 运行，当时 success=0 并且 returns 布局错误。

现在的底线是这样的，

我创建名为 success
和内部 onCreateViewHolder() 方法我存储 success
然后，我将这个 success 变量用于我的两种方法

这是我目前运行良好的解决方案。

 private int success;

    // Constructor
    public HitsOnSchemesDataDisplayAdapter(Context context){
        layoutInflater = LayoutInflater.from(context);
    }

    public void setSchemesListHitsWise(ArrayList<SchemesHitsPojoModel> schemesListHitsWise){
        this.schemesListHitsWise = schemesListHitsWise;
        notifyItemRangeChanged(0, schemesListHitsWise.size());
    }

onCreateViewHolder() 方法

@Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = null;
        MyViewHolder viewHolder;
        SchemesHitsPojoModel firstObject = schemesListHitsWise.get(0);
        success = firstObject.getSuccess();
        switch (success){
            case(0):
                view = layoutInflater.inflate(R.layout.custom_no_record_found_msg_screen, parent, false);
                Log.d("VIEW "," is runned....");
                break;
            case(1):
                view = layoutInflater.inflate(R.layout.custom_recyclerview_row_each_scheme_hits, parent,false);
                Log.d("VIEW_2, "," is run....");
                break;

            default:
                view = layoutInflater.inflate(R.layout.custom_no_record_found_msg_screen, parent, false);
                break;
        }
        viewHolder = new MyViewHolder(view);
        return viewHolder;
    }

onBindViewHolder() 方法

 @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        SchemesHitsPojoModel firstObject = schemesListHitsWise.get(0);
        //int success = firstObject.getSuccess();
        if(success == 0 ){
            Log.d("SORRY!, "," We don't have any records to show you.");
        }
        else if(success == 1){
            SchemesHitsPojoModel currentSchemeRow =  schemesListHitsWise.get(position);
            holder.schemeName.setText(currentSchemeRow.getSchemeName());
            int langId = currentSchemeRow.getLanguage_id();
            switch(langId){
                case(1):
                    holder.languageName.setText("Punjabi");
                    break;
                case(2):
                    holder.languageName.setText("English");
            }

            holder.schemeViewDate.setText(currentSchemeRow.getSchemeViewDate());
            holder.schemeHits.setText(String.valueOf(currentSchemeRow.getSchemeHits()));
            holder.viewIcon.setImageResource(R.drawable.ic_remove_red_eye_black_18dp);
            //holder.totalHitsOnThisScheme.setText(currentSchemeRow.getSchemeTotalHitsCount());
        }
    }

RecyclerViewAdapter 的 onBindViewHolder() 方法出错

Error in RecyclerViewAdapter's onBindViewHolder() Method

android

android-adapter

android-recyclerview