java - 单击 ListView 中的项目会使应用程序崩溃

Question

我有问题。当我单击 ExpandableListView 中的项目时，我的应用程序崩溃了。我不知道问题出在哪里。在 Manifest.xml 中，我添加了 ButelkaPlastikowa.java。有任何想法吗？SegregateWasteActivity.java

public class SegregateWasteActivity extends Activity implements SearchView.OnQueryTextListener, SearchView.OnCloseListener {
    private SearchView search;
    private MyListAdapter listAdapter;
    private ExpandableListView myList;
    private ArrayList<Alphabet> alphabetList = new ArrayList<Alphabet>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.segregate_waste_activity);


        SearchManager searchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
        search = (SearchView) findViewById(R.id.search);
        search.setSearchableInfo(searchManager.getSearchableInfo(getComponentName()));
        search.setIconifiedByDefault(false);
        search.setOnQueryTextListener(this);
        search.setOnCloseListener(this);

        displayList();
        expandAll();


        myList.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {

            @Override
            public boolean onChildClick(ExpandableListView elv, View view,
                    int groupPosition, int childPosition, long id) {
                // TODO Auto-generated method stub
                TextView tv = (TextView) view.findViewById(R.id.name);
                String name = (String) tv.getText();

                try{
                    if(name.contains("Akumulatory samochodowe")){

                        Intent intent1 = new Intent(SegregateWasteActivity.this, Akumulatory.class);
                        startActivity(intent1);
                    }
                    else if (name.contains("Armatura sanitarna")){

                        Intent intent1 = new Intent(SegregateWasteActivity.this, Armatura.class);
                        startActivity(intent1);
                    }
                    else if (name.contains("Artykuły higieniczne")){

                        Intent intent1 = new Intent(SegregateWasteActivity.this, Higiena.class);
                        startActivity(intent1);
                    }
                    else if (name.contains("Artykuły zawierające rtęć")){

                        Intent intent1 = new Intent(SegregateWasteActivity.this, Rtec.class);
                        startActivity(intent1);
                    }
                    else if (name.contains("Butelka plastikowa")){

                        Intent intent1 = new Intent(SegregateWasteActivity.this, ButelkaPlastikowa.class);
                        startActivity(intent1);
                    }
Class cls = Class.forName("com.odpad.odpadygdansk.waste." + name);

                    Intent intent = new Intent(SegregateWasteActivity.this, cls);
                    startActivity(intent);


                }
                catch(ClassNotFoundException e){
                    e.printStackTrace();
                }
                return false;
            }
        });

    }


    @Override
    public boolean onClose() {
        // TODO Auto-generated method stub
        listAdapter.filterData("");
        expandAll();
        return false;
    }

    @Override
    public boolean onQueryTextSubmit(String query) {
        // TODO Auto-generated method stub
        listAdapter.filterData(query);
        expandAll();
        return false;
    }

    @Override
    public boolean onQueryTextChange(String newText) {
        // TODO Auto-generated method stub
        listAdapter.filterData(newText);
        expandAll();
        return false;
    }

    private void expandAll()
    {
        int count = listAdapter.getGroupCount();
        for(int i = 0; i < count; i++)
        {
            myList.expandGroup(i);
        }
    }

    private void displayList()
    {
        loadSomeData();

        myList = (ExpandableListView) findViewById(R.id.expandableList);

        listAdapter = new MyListAdapter(SegregateWasteActivity.this, alphabetList);

        myList.setAdapter(listAdapter);
    }

    private void loadSomeData()
    {
        ArrayList<Waste> wasteList = new ArrayList<Waste>();
        Waste waste = new Waste("Aerozol");
        wasteList.add(waste);
        waste = new Waste("Akumulatory samochodowe");
        wasteList.add(waste);
        waste = new Waste("Armatura sanitarna");
        wasteList.add(waste);
        waste = new Waste("Artykuły higieniczne");
        wasteList.add(waste);
        waste = new Waste("Artykuły zawierające rtęć");
        wasteList.add(waste);

        Alphabet alphabet = new Alphabet("A", wasteList);
        alphabetList.add(alphabet);

        wasteList = new ArrayList<Waste>();
        waste = new Waste("Bateria");
        wasteList.add(waste);
        waste = new Waste("Butelka plastikowa");
        wasteList.add(waste);
alphabet = new Alphabet("B", wasteList);
        alphabetList.add(alphabet);
}
}

我的代码:ButelkaPlastikowa.java

public class ButelkaPlastikowa extends Activity{
    ImageView mapOfWaste;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // you have to create game.xml 
        setContentView(R.layout.plastic_bottle);

        TextView plastic_bottle = (TextView) findViewById(R.id.TextViewPlasticBottle);
        plastic_bottle.setText(Html.fromHtml(getString(R.string.plastic_bottle)));

        mapOfWasteActivity();
    }
    /** Called when the user clicks the ImageView */
    public void mapOfWasteActivity() {
        mapOfWaste = (ImageView)findViewById(R.id.imageViewMap);
        mapOfWaste.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(isNetworkConnected()){
                    Intent intent = new Intent(ButelkaPlastikowa.this, MapOfWasteActivity.class);
                    startActivity(intent);
                }else{
                    Intent intent = new Intent(ButelkaPlastikowa.this,NoInternet.class);
                    startActivity(intent);
                }
            }
        });

    }
    public boolean isNetworkConnected(){
        boolean isConnected = false;
        try{
            ConnectivityManager cm = (ConnectivityManager) this.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
            isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
            return isConnected;
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return isConnected;

    }

}

日志

 11-22 20:24:19.513: E/AndroidRuntime(32357): FATAL EXCEPTION: main
    11-22 20:24:19.513: E/AndroidRuntime(32357): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.odpad.odpadygdansk/com.odpad.odpadygdansk.waste.ButelkaPlastikowa}: java.lang.NullPointerException
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2062)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2087)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.ActivityThread.access$600(ActivityThread.java:133)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1198)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.os.Handler.dispatchMessage(Handler.java:99)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.os.Looper.loop(Looper.java:137)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.ActivityThread.main(ActivityThread.java:4803)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at java.lang.reflect.Method.invokeNative(Native Method)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at java.lang.reflect.Method.invoke(Method.java:511)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at dalvik.system.NativeStart.main(Native Method)
    11-22 20:24:19.513: E/AndroidRuntime(32357): Caused by: java.lang.NullPointerException
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at com.odpad.odpadygdansk.waste.ButelkaPlastikowa.mapOfWasteActivity(ButelkaPlastikowa.java:35)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at com.odpad.odpadygdansk.waste.ButelkaPlastikowa.onCreate(ButelkaPlastikowa.java:30)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.Activity.performCreate(Activity.java:5008)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
    11-22 20:24:19.513: E/AndroidRuntime(32357):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2026)

<小时/>

我的 Plastic_bottle.xml

<?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="vertical" >

    <ImageView
        android:id="@+id/dangerous_waste"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:src="@drawable/odpady_niebezpieczne" />

<ScrollView
    android:layout_width="fill_parent"
    android:layout_height="300dp">

    <LinearLayout 
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

    <ImageView
        android:id="@+id/obraz_aerozol2"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:src="@drawable/aerozol2" />

    <TextView
        android:id="@+id/TextViewPlasticBottle"
        android:layout_width="match_parent"
        android:layout_height="800dp"
        android:text="@string/plastic_bottle" />

    </LinearLayout>
</ScrollView>
    <ImageView
        android:id="@+id/imageViewPinezka"
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:onClick="mapOfWasteActivity"
        android:src="@drawable/pinezka" />

</LinearLayout>

Answer 1

您遇到的问题是您的 xml 文件中没有 id 为“imageViewMap”的 View 。

这会导致 findViewById(R.id.imageViewMap); 返回 null，然后您尝试在 null 对象上调用函数。

我不确定您要在哪个 View 上设置 OnClickListener，但您需要添加 android:id="@+id/imageViewMap"到 xml 中的该 View 。