java - 由于自定义 ArrayAdapter 类中的 NullPointerException，应用程序崩溃

Question

我正在参加关于多屏应用的免费 Udacity 课程。我已经学会了如何使用自定义 ArrayList 在 ListView 中显示个性化的“一组”视图。我正在练习，我找不到我的错误。

该项目由以下人员组成：

我要重复显示的视图集：

package com.example.administrator.learncolors;

import android.view.View;

// Creo l'oggetto che rappresenta il set di immagine e due TextView della lista

public class setTextViewCatalogue {

    // Inizializzo una variabile per ogni oggetto

    private String mColorImg;
    private String mNomeColore;
    private String mCodiceColore;

    // Inizializzo variabili pubbliche per richiamarle dall'esterno
    public setTextViewCatalogue(String colorImg, String nomeColore, String codiceColore) {
        mColorImg = colorImg;
        mNomeColore = nomeColore;
        mCodiceColore = codiceColore;
    }

    // Definisco i metodi in public
    public String getColorImg() {return mColorImg;}
    public String getNomeColore() {return mNomeColore;}
    public String getCodiceColore() {return mCodiceColore;}

}

使用这组视图的个性化 ArrayAdapter：

package com.example.administrator.learncolors;

import android.app.Activity;
import android.graphics.Color;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.ArrayList;

public class setTextViewCatalogueAdapter
        extends ArrayAdapter<setTextViewCatalogue> {

    public setTextViewCatalogueAdapter(Activity context, ArrayList<setTextViewCatalogue> fullSetColor) {
        super (context, 0, fullSetColor);
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        // Check if the existing view is being reused, otherwise inflate the view
        View listItemView = convertView;
        if(listItemView == null) {
            listItemView = LayoutInflater.from(getContext()).inflate(
                    R.layout.colors_list_item, parent, false);
        }

        setTextViewCatalogue currentSetTextViewCatalogue = getItem(position);

        View viewColorImg = listItemView.findViewById(R.id.viewImg);
        viewColorImg.setBackgroundColor(Color.parseColor(currentSetTextViewCatalogue.getColorImg()));

        TextView textViewNomeColore = listItemView.findViewById(R.id.textViewNomeColore);
        textViewNomeColore.setText(currentSetTextViewCatalogue.getNomeColore());

        TextView textViewCodiceColore = listItemView.findViewById(R.id.textViewCodiceColore);
        textViewCodiceColore.setText(currentSetTextViewCatalogue.getCodiceColore());

        return listItemView;

    }
}

以及我实现个性化 ArrayList 的活动（崩溃）：

package com.example.administrator.learncolors;

import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;

import java.util.ArrayList;

public class ColorsCatalogue extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_colors_catalogue);

        ArrayList<setTextViewCatalogue> arrayListCatalogo = new ArrayList<>();
        arrayListCatalogo.add(new setTextViewCatalogue("#ff80ff", "Rosso", "Codice Rosso"));

        setTextViewCatalogueAdapter adapter = new setTextViewCatalogueAdapter(this,arrayListCatalogo);
        ListView listView = findViewById(R.id.catalogueListView);
        listView.setAdapter(adapter);

    }
}

这些是 XML 布局。

崩溃的活动（列表视图）：

<?xml version="1.0" encoding="utf-8"?>
<ListView
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:id="@+id/catalogueListView"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ColorsCatalogue">
</ListView>

这是项目的布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:weightSum="100"
    android:padding="8dp">

        <view
            android:layout_width="wrap_content"
            android:id="@+id/viewImg"
            android:layout_weight="10"
            android:layout_height="48dp"
            android:layout_marginRight="8dp"/>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_weight="90"
            android:layout_height="48dp"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/textViewNomeColore" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:id="@+id/textViewCodiceColore" />

        </LinearLayout>

</LinearLayout>

Android Studio 没有显示错误，但是当我尝试启动 Activity 时应用程序崩溃。这些是日志细节：

07-31 10:07:08.197 5324-5324/com.example.administrator.learncolors E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.administrator.learncolors, PID: 5324
    android.view.InflateException: Binary XML file line #10: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
        at android.view.LayoutInflater.inflate(LayoutInflater.java:539)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:423)
        at com.example.administrator.learncolors.setTextViewCatalogueAdapter.getView(setTextViewCatalogueAdapter.java:28)
        at android.widget.AbsListView.obtainView(AbsListView.java:2346)
        at android.widget.ListView.makeAndAddView(ListView.java:1875)
        at android.widget.ListView.fillDown(ListView.java:702)
        at android.widget.ListView.fillFromTop(ListView.java:763)
        at android.widget.ListView.layoutChildren(ListView.java:1684)
        at android.widget.AbsListView.onLayout(AbsListView.java:2148)
        at android.view.View.layout(View.java:16630)
        at android.view.ViewGroup.layout(ViewGroup.java:5437)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
        at android.view.View.layout(View.java:16630)
        at android.view.ViewGroup.layout(ViewGroup.java:5437)
        at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:443)
        at android.view.View.layout(View.java:16630)
        at android.view.ViewGroup.layout(ViewGroup.java:5437)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
        at android.view.View.layout(View.java:16630)
        at android.view.ViewGroup.layout(ViewGroup.java:5437)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
        at android.view.View.layout(View.java:16630)
        at android.view.ViewGroup.layout(ViewGroup.java:5437)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
        at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2678)
        at android.view.View.layout(View.java:16630)
        at android.view.ViewGroup.layout(ViewGroup.java:5437)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2171)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1931)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858)
        at android.view.Choreographer.doCallbacks(Choreographer.java:670)
        at android.view.Choreographer.doFrame(Choreographer.java:606)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844)
        at android.os.Handler.handleCallback(Handler.java:739)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:148)
        at android.app.ActivityThread.main(ActivityThread.java:5417)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
     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:738)
        at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:704)
        at android.view.LayoutInflater.rInflate(LayoutInflater.java:835)
        at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:798)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:515)
        at android.view.LayoutInflater.inflate(LayoutInflater.java:423) 
        at com.example.administrator.learncolors.setTextViewCatalogueAdapter.getView(setTextViewCatalogueAdapter.java:28) 
        at android.widget.AbsListView.obtainView(AbsListView.java:2346) 
        at android.widget.ListView.makeAndAddView(ListView.java:1875) 
        at android.widget.ListView.fillDown(ListView.java:702) 
        at android.widget.ListView.fillFromTop(ListView.java:763) 
        at android.widget.ListView.layoutChildren(ListView.java:1684) 
        at android.widget.AbsListView.onLayout(AbsListView.java:2148) 
        at android.view.View.layout(View.java:16630) 
        at android.view.ViewGroup.layout(ViewGroup.java:5437) 
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336) 
        at android.widget.FrameLayout.onLayout(FrameLayout.java:273) 
        at android.view.View.layout(View.java:16630) 
        at android.view.ViewGroup.layout(ViewGroup.java:5437) 
        at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:443) 
        at android.view.View.layout(View.java:16630) 
        at android.view.ViewGroup.layout(ViewGroup.java:5437) 
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336) 
        at android.widget.FrameLayout.onLayout(FrameLayout.java:273) 
        at android.view.View.layout(View.java:16630) 
        at android.view.ViewGroup.layout(ViewGroup.java:5437) 
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743) 
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586) 
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1495) 
        at android.view.View.layout(View.java:16630) 
        at android.view.ViewGroup.layout(ViewGroup.java:5437) 
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336) 
        at android.widget.FrameLayout.onLayout(FrameLayout.java:273) 
        at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2678) 
        at android.view.View.layout(View.java:16630) 
        at android.view.ViewGroup.layout(ViewGroup.java:5437) 
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2171) 
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1931) 
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1107) 
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6013) 
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:858) 
        at android.view.Choreographer.doCallbacks(Choreographer.java:670) 
        at android.view.Choreographer.doFrame(Choreographer.java:606) 
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:844) 
        at android.os.Handler.handleCallback(Handler.java:739) 
        at android.os.Handler.dispatchMessage(Handler.java:95) 
        at android.os.Looper.loop(Looper.java:148) 
        at android.app.ActivityThread.main(ActivityThread.java:5417) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)