尝试在空对象引用上调用虚拟方法“int java.lang.String.length()”
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Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
提问by Personal Jesus
So I have Android app with Tabs and RecyclerView. When I run my app, it crashes.
所以我有带有 Tabs 和RecyclerView. 当我运行我的应用程序时，它崩溃了。
logcat:
日志猫：
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at java.io.StringReader.<init>(StringReader.java:47)
at android.text.HtmlToSpannedConverter.convert(Html.java:442)
at android.text.Html.fromHtml(Html.java:136)
at android.text.Html.fromHtml(Html.java:99)
at com.example.app.MyRecyclerViewAdapter2.onBindViewHolder(MyRecyclerViewAdapter2.java:80)
at com.example.app.MyRecyclerViewAdapter2.onBindViewHolder(MyRecyclerViewAdapter2.java:17)
...
at com.example.app.MyRecyclerViewAdapter2.onBindViewHolder(MyRecyclerViewAdapter2.java:80)
在 com.example.app.MyRecyclerViewAdapter2.onBindViewHolder(MyRecyclerViewAdapter2.java:80)
It points to this line of the code
它指向这行代码
listRowViewHolder.postId.setText(Html.fromHtml(listItems.getPostId())); // This line of code leads to crashing of app
If I delete this line, my app will work fine.
如果我删除这一行，我的应用程序将正常工作。
MyRecyclerViewAdapter2.java:
MyRecyclerViewAdapter2.java：
package com.example.app;
import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.RecyclerView;
import android.text.Html;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.android.volley.toolbox.ImageLoader;
import java.util.List;
public class MyRecyclerViewAdapter2 extends RecyclerView.Adapter<ListRowViewHolder> {
private List<ListItems> listItemsList;
private Context mContext;
private ImageLoader mImageLoader;
private int focusedItem = 0;
public MyRecyclerViewAdapter2(Context context, List<ListItems> listItemsList) {
this.mContext = context;
this.listItemsList = listItemsList;
}
@Override
public ListRowViewHolder onCreateViewHolder(final ViewGroup viewGroup, int position) {
View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.card_view_row2, null);
ListRowViewHolder holder = new ListRowViewHolder(v);
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
TextView postUrl = (TextView) v.findViewById(R.id.postId);
String post_Id = postUrl.getText().toString();
Intent intent = new Intent(mContext, ViewPostActivity.class);
intent.putExtra("id", post_Id);
mContext.startActivity(intent);
}
});
return holder;
}
@Override
public void onBindViewHolder(ListRowViewHolder listRowViewHolder, int position) {
ListItems listItems = listItemsList.get(position);
listRowViewHolder.itemView.setSelected(focusedItem == position);
listRowViewHolder.getLayoutPosition();
mImageLoader = MySingleton.getInstance(mContext).getImageLoader();
listRowViewHolder.thumbnail.setImageUrl(listItems.getThumbnail(), mImageLoader);
listRowViewHolder.thumbnail.setDefaultImageResId(R.drawable.website_placeholder);
listRowViewHolder.title.setText(Html.fromHtml(listItems.getTitle()));
listRowViewHolder.date.setText(Html.fromHtml(listItems.getDate()));
listRowViewHolder.content.setText(Html.fromHtml(listItems.getContent()));
listRowViewHolder.postId.setText(Html.fromHtml(listItems.getPostId())); // This line of code leads to crashing of app
}
public void clearAdapter () {
listItemsList.clear();
notifyDataSetChanged();
}
@Override
public int getItemCount() {
return (null != listItemsList ? listItemsList.size() : 0);
}}
回答by sonic
Your error because means that you call Html.fromHtmlon a null string.
You should test the value of listItems.getPostId()before calling Html.fromHtml.
你的错误因为意味着你调用Html.fromHtml了一个空字符串。您应该listItems.getPostId()在调用 之前测试 的值Html.fromHtml。
