java - ArrayAdapter 中 onCreateViewHolder 中的 NullPointerException

Question

我正在尝试制作 RecyclerView，但遇到了这个奇怪的错误。

消息如下:

android.view.InflateException: Binary XML file line #0: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
                  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
                      at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:761)
                      at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:727)
                      at android.view.LayoutInflater.rInflate(LayoutInflater.java:858)
                      at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:821)
                      at android.view.LayoutInflater.inflate(LayoutInflater.java:518)
                      at android.view.LayoutInflater.inflate(LayoutInflater.java:426)
                      at com.example.eddie.songs3.AdapterRegularItem.onCreateViewHolder(AdapterRegularItem.java:34)
                      at com.example.eddie.songs3.AdapterRegularItem.onCreateViewHolder(AdapterRegularItem.java:15)
                      at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6493)
                      at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5680)
                      at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5563)
                      at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5559)
                      at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2229)
                      at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1556)
                      at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1516)
                      at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:608)
                      at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3693)
                      at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3410)
                      at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3962)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
                      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
                      at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1172)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
                      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
                      at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
                      at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
                      at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
E/AndroidRuntime:     at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
                      at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
                      at com.android.internal.policy.DecorView.onLayout(DecorView.java:759)
                      at android.view.View.layout(View.java:17745)
                      at android.view.ViewGroup.layout(ViewGroup.java:5645)
                      at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2491)
                      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2206)
                      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1348)
                      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6858)
                      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:887)
                      at android.view.Choreographer.doCallbacks(Choreographer.java:699)
                      at android.view.Choreographer.doFrame(Choreographer.java:634)
                      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:873)
                      at android.os.Handler.handleCallback(Handler.java:751)
                      at android.os.Handler.dispatchMessage(Handler.java:95)
                      at android.os.Looper.loop(Looper.java:154)
                      at android.app.ActivityThread.main(ActivityThread.java:6351)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:896)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:786)
Application terminated.

这是我的 SearchActivity。这是显示 RecyclerView

的 activity

NavigationView navView;
    boolean startedBySplashAct = false;
    RecyclerView recyclerView;
    ArrayList<RegularItem> regularItemList;

    AdapterRegularItem arrayAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //see if this activity was started by splash activity
        Intent intent = getIntent();
        String intentStr = intent.getStringExtra("parent_activity");
        if(intentStr != null && intentStr.equals("splash"))
            startedBySplashAct = true;

        navView = findViewById(R.id.nav_view);
        regularItemList = new ArrayList<>();

        arrayAdapter = new AdapterRegularItem(R.layout.regular_item_layout, regularItemList, SearchActivityReg.this);

        //set the corresponding item checked
        navView.getMenu().getItem(0).setChecked(true);

        //set needed properties for recuclerView
        recyclerView = findViewById(R.id.RecyclerViewReg);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(arrayAdapter);



        String number = "67";
        String line = "I have decided, I am gonna fight it";

        RegularItem item = new RegularItem(number, line);
        regularItemList.add(item);

        arrayAdapter = new AdapterRegularItem(R.layout.regular_item_layout, regularItemList, SearchActivityReg.this);
        recyclerView.setAdapter(arrayAdapter);

    }

其余部分我没有展示，因为它与问题无关。

这里是 ArrayAdapter，这是错误所在。

package com.example.eddie.songs3;

import android.content.Context;
import android.speech.tts.TextToSpeech;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

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

public class AdapterRegularItem extends RecyclerView.Adapter<AdapterRegularItem.ViewHolder>
{
    int listItemLayout;

    ArrayList<RegularItem> itemsList;
    static Context c;

    public AdapterRegularItem(int layoutID, ArrayList<RegularItem> itemList,
                              Context c)
    {
        this.listItemLayout = layoutID;
        this.itemsList = itemList;
        this.c = c;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext())

                //this is where the error is
                .inflate(
                        R.layout.regular_item_layout,
                        parent,
                        false);

        ViewHolder myViewHolder = new ViewHolder(v);
        return  myViewHolder;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        TextView number = holder.number;
        TextView firstLine = holder.firstLine;

        number.setText(itemsList.get(position).getNumber());
        firstLine.setText(itemsList.get(position).getFirstLine());
    }

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

    static class ViewHolder extends RecyclerView.ViewHolder implements
            View.OnClickListener
    {
        public TextView number;
        public TextView firstLine;

        public ViewHolder(View itemView)
        {
            super(itemView);
            itemView.setOnClickListener(this);
            number = itemView.findViewById(R.id.txtNumber);
            firstLine = itemView.findViewById(R.id.txtFirstLine);
        }

        @Override
        public void onClick(View view)
        {

        }
    }
}

这里是 RegualrItem.java

package com.example.eddie.songs3;

public class RegularItem
{    String number;
    String firstLine;
    public RegularItem(String number, String firstLine)
    {
        this.firstLine = firstLine;
        this.number =  number;
    }

    public String getNumber()
    {
        return number;
    }

    public String getFirstLine()
    {
        return firstLine;
    }


}

regular_item_layout.xml 这是列表中每个项目的布局

<?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="wrap_content">

<TextView
    android:id="@+id/txtNumber"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="120"
    android:layout_marginStart="16dp"
    android:textColor="@color/textItemNumber"
    android:textSize="16sp"/>

    <TextView
        android:id="@+id/txtFirstLine"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:singleLine="true"
        android:layout_marginStart="72dp"
        android:text="Just testing to see"
        android:textSize="16sp"
        android:textColor="@color/textColorMain"
        android:layout_marginEnd="16dp"/>

    <view
        android:id="@+id/devider"
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:layout_below="@id/txtNumber"/>

</RelativeLayout>

我想我要展示的还不止这些，如果还有其他的，请告诉我。问题是我是从我以前制作的应用程序中复制它的，它在那里工作得很好，所以我什至不知道在代码中的什么地方寻找问题。

Answer 1

在你的布局中，你有这个标签:

<view
    android:id="@+id/devider"
    android:layout_width="match_parent"
    android:layout_height="1dp"
    android:layout_below="@id/txtNumber"/>

将 view 更改为 View(大写 V)。