我尝试创建一个 XML 文件,该文件采用一个简单的 listeView 设置,个人适配器如下所示:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<ListView
android:id="@+id/listpromo"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>
</LinearLayout>
和我的活动:
public class ListSample_category3 extends Activity
{
public final static String ITEM_TITLE = "title";
public final static String ITEM_COMPANY= "company";
public final static String ITEM_DATE = "availabledate";
private ListView list;
public Map<String,?> createItem(String title, String company, String date)
{
Map<String,String> item = new HashMap<String,String>();
item.put(ITEM_TITLE, title);
item.put(ITEM_COMPANY, company);
item.put(ITEM_DATE, date);
return item;
}
@Override
public void onCreate(Bundle bundle)
{
super.onCreate(bundle);
List<Map<String,?>> security = new LinkedList<Map<String,?>>();
security.add(createItem("Remember passwords", "Cisco", "2012-02-10"));
security.add(createItem("Clear passwords", "Microsoft", "2012-02-10"));
security.add(createItem("Show security warnings", "Apple", "2012-02-10"));
// create our list and custom adapter
SeparatedListAdapter adapter = new SeparatedListAdapter(this);
adapter.addSection("Categorie 1", new ArrayAdapter<String>(this,
R.layout.list_item_category3, new String[] { "First item", "Item two" }));
adapter.addSection("Categorie 2", new SimpleAdapter(this, security, R.layout.list_complex_category3,
new String[] { ITEM_TITLE, ITEM_COMPANY, ITEM_DATE }, new int[] { R.id.list_complex_title, R.id.list_complex_company, R.id.list_complex_date }));
// create ListView
//ListView list = new ListView(this);
list = (ListView) findViewById(R.id.listpromo);
// OnItemClickListener on all items
OnItemClickListener listener = new OnItemClickListener()
{
public void onItemClick(AdapterView<?> parent, View view, int position, long id)
{
}
};
list.setOnItemClickListener(listener);
list.setItemsCanFocus(true);
list.setAdapter(adapter);
this.setContentView(list);
}
}
但我有一个 NullPointerException :
08-05 17:00:26.304: E/AndroidRuntime(3226): FATAL EXCEPTION: main
08-05 17:00:26.304: E/AndroidRuntime(3226): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dev.prixo/com.dev.prixo.OngletsActivity}: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dev.prixo/com.dev.prixo.ListSample_category3}: java.lang.NullPointerException
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.os.Handler.dispatchMessage(Handler.java:99)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.os.Looper.loop(Looper.java:130)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.main(ActivityThread.java:3687)
08-05 17:00:26.304: E/AndroidRuntime(3226): at java.lang.reflect.Method.invokeNative(Native Method)
08-05 17:00:26.304: E/AndroidRuntime(3226): at java.lang.reflect.Method.invoke(Method.java:507)
08-05 17:00:26.304: E/AndroidRuntime(3226): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
08-05 17:00:26.304: E/AndroidRuntime(3226): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
08-05 17:00:26.304: E/AndroidRuntime(3226): at dalvik.system.NativeStart.main(Native Method)
08-05 17:00:26.304: E/AndroidRuntime(3226): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dev.prixo/com.dev.prixo.ListSample_category3}: java.lang.NullPointerException
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.startActivityNow(ActivityThread.java:1491)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:676)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.widget.TabHost.setCurrentTab(TabHost.java:348)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.widget.TabHost.addTab(TabHost.java:227)
08-05 17:00:26.304: E/AndroidRuntime(3226): at com.dev.prixo.OngletsActivity.onCreate(OngletsActivity.java:34)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
08-05 17:00:26.304: E/AndroidRuntime(3226): ... 11 more
08-05 17:00:26.304: E/AndroidRuntime(3226): Caused by: java.lang.NullPointerException
08-05 17:00:26.304: E/AndroidRuntime(3226): at com.dev.prixo.ListSample_category3.onCreate(ListSample_category3.java:77)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
08-05 17:00:26.304: E/AndroidRuntime(3226): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
08-05 17:00:26.304: E/AndroidRuntime(3226): ... 20 more
请告诉我该怎么做,请..
这是我的 SeperatedListAdapter:
public class SeparatedListAdapter extends BaseAdapter
{
public final Map<String,Adapter> sections = new LinkedHashMap<String,Adapter>();
public final ArrayAdapter<String> headers;
public final static int TYPE_SECTION_HEADER = 0;
public SeparatedListAdapter(Context context)
{
headers = new ArrayAdapter<String>(context, R.layout.list_header_category3);
}
public void addSection(String section, Adapter adapter)
{
this.headers.add(section);
this.sections.put(section, adapter);
}
public Object getItem(int position)
{
for(Object section : this.sections.keySet())
{
Adapter adapter = sections.get(section);
int size = adapter.getCount() + 1;
// check if position inside this section
if(position == 0) return section;
if(position < size) return adapter.getItem(position - 1);
// otherwise jump into next section
position -= size;
}
return null;
}
public int getCount()
{
// total together all sections, plus one for each section header
int total = 0;
for(Adapter adapter : this.sections.values())
total += adapter.getCount() + 1;
return total;
}
public int getViewTypeCount()
{
// assume that headers count as one, then total all sections
int total = 1;
for(Adapter adapter : this.sections.values())
total += adapter.getViewTypeCount();
return total;
}
public int getItemViewType(int position)
{
int type = 1;
for(Object section : this.sections.keySet())
{
Adapter adapter = sections.get(section);
int size = adapter.getCount() + 1;
// check if position inside this section
if(position == 0) return TYPE_SECTION_HEADER;
if(position < size) return type + adapter.getItemViewType(position - 1);
// otherwise jump into next section
position -= size;
type += adapter.getViewTypeCount();
}
return -1;
}
public boolean areAllItemsSelectable()
{
return false;
}
public boolean isEnabled(int position)
{
return (getItemViewType(position) != TYPE_SECTION_HEADER);
}
public View getView(int position, View convertView, ViewGroup parent)
{
int sectionnum = 0;
for(Object section : this.sections.keySet()) {
Adapter adapter = sections.get(section);
int size = adapter.getCount() + 1;
// check if position inside this section
if(position == 0) return headers.getView(sectionnum, convertView, parent);
if(position < size) return adapter.getView(position - 1, convertView, parent);
// otherwise jump into next section
position -= size;
sectionnum++;
}
return null;
}
public long getItemId(int position)
{
return position;
}
}