[英]Error in RecyclerViewAdapter's onBindViewHolder() Method
伙计们,您可能会像其他NullPionterException问题一样与您相似,在将其标记为重复之前,请先阅读并尝试先了解我的问题,然后指出我的问题所在。
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,然后将该对象放入某些ArrayList<SchemesHitsPojoModel> schemesListHitsWise
然后将该ArrayList发送到我的RecyclerViewAdapter类,然后在RecyclerView中显示它。
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。 帮帮我,我最近几天试图解决此问题,并阅读了很多答案,但仍然存在此错误。
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);
}
}
RecyclerView的自定义行的XML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>
我认为你的问题在这里
holder.schemeName.setText(currentSchemeRow.getSchemeName());
更改为
holder.schemeName.setText(currentSchemeRow.get(position).getSchemeName()
);
移动
SchemesHitsPojoModel currentSchemeRow = schemesListHitsWise.get(position);
别的方法
你需要改变
有两次机会得到此错误。
1.改变你的
holder.schemeViewDate.setText(currentSchemeRow.getSchemeViewDate());
holder.schemeHits.setText(String.valueOf(currentSchemeRow.getSchemeHits()));
至
holder.schemeViewDate.setText(currentSchemeRow.get(position).getSchemeViewDate());
holder.schemeHits.setText("" + currentSchemeRow..get(position).getSchemeHits());
currentSchemeRow应该是您的模型的Arraylist,您可以在其中获取和设置数据,并且必须从作为所选位置的get(position)获取值。
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);
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,您要膨胀两种不同的布局,因此所有TexViews必须同时出现在两种布局中。
要么
在onBindViewHolder中放置一个if条件来处理空指针异常,因为在两种情况下都必须调用onBindViewHolder。
首先,谢谢大家,我非常感谢您的帮助。 其实这是我的坏事。
我将success
变量的值存储在onBindViewHolder()
,这将用于两种方法(onCreateViewHolder(),onBindViewHolder()),这是我的实际错误
因为我忘记了我在onCreateViewHolder()
中也使用了此success
变量来为特定情况选择我的特定布局,并且因为在我的onCtreatViewHolder()
运行时出现此错误,所以success=0
并返回了错误的布局。
现在最重要的是,
我创建名为success
的全局变量
在onCreateViewHolder()
方法中,我存储success
的值
然后,我将这success
变量用于两种方法
这是我目前可以正常工作的解决方案。
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());
}
}
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