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我想在我的项目顶部添加一个按钮，但我真的不知道如何使用我的基本适配器实现它。

我有两个以文本视图为首的列表，我遇到的问题是在我的两个列表之上实现一个简单的按钮以创建一个刷新按钮，但我真的不知道在哪里插入这个静态按钮。

这是我的活动：

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";

    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 }));

        ListView list = new ListView(this);
        list.setAdapter(adapter);
        this.setContentView(list);

    }
}

我的基本适配器

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;
    }
}

我的 3 个 xml 文件：

<!-- list_header.xml -->
<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/list_header_title"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"
    android:paddingTop="2dip"
    android:paddingBottom="2dip"
    android:paddingLeft="5dip"
    style="?android:attr/listSeparatorTextViewStyle" />


<!-- list_item.xml -->
<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/list_item_title"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"
    android:paddingTop="10dip"
    android:paddingBottom="10dip"
    android:paddingLeft="15dip"
    android:textAppearance="?android:attr/textAppearanceLarge"
    />

<!-- list_complex.xml -->
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:paddingTop="10dip"
    android:paddingBottom="10dip"
    android:paddingLeft="15dip"
    >
    <TextView
        android:id="@+id/list_complex_title"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        />
    <TextView
        android:id="@+id/list_complex_caption"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceSmall"
        />
</LinearLayout>

从这段代码中，我有 2 个以 textview 为首的列表，我遇到的问题是在我的 2 个列表顶部实现一个简单按钮以进行刷新（按钮），但是在使用这种方式时，我真的不知道在哪里插入这个静态按钮

编辑 ：

我试图制作一个像这样的其他 xml 文件：

<?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>

我将我的活动更改为：

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 14:49:24.875: E/AndroidRuntime(2558): 致命异常: main 08-05 14:49:24.875: E/AndroidRuntime(2558): java.lang.RuntimeException: 无法启动活动 ComponentInfo{com. dev.prixo/com.dev.prixo.OngletsActivity}：java.lang.RuntimeException：无法启动活动 ComponentInfo{com.dev.prixo/com.dev.prixo.ListSample_category3}：java.lang.NullPointerException 08-05 14： 49:24.875: E/AndroidRuntime(2558): 在 android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651) 08-05 14:49:24.875: E/AndroidRuntime(2558): 在 android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:1667) 08-05 14:49:24.875: E/AndroidRuntime(2558): 在 android.app.ActivityThread.access$1500(ActivityThread.java:117) 08-05 14:49:24.875: E/ AndroidRuntime(2558): 在 android.app.ActivityThread$H.handleMessage(ActivityThread.java:935) 08-05 14:49:24.875: E/AndroidRuntime(2558): 在 android.os.Handler.dispatchMessage(Handler.java:99) 08-05 14:49:24.875: E/AndroidRuntime(2558): 在android.os.Looper.loop(Looper.java:130) 08-05 14:49:24.875: E/AndroidRuntime(2558): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.dev.prixo /com.dev.prixo.ListSample_category3}：java.lang.NullPointerException

请告诉我该怎么做，请..

4

2 回答 2

2

根据您的设计，您的问题是您正在根据 ListView 对象设置 contentView：

ListView list = new ListView(this);
list.setAdapter(adapter);
this.setContentView(list);

这是一个单一的对象，如果您想修改它并更改该特定活动的内容，显然会导致问题。

我的建议

您需要创建一个可以在 contentView 中设置的布局 xml 文件。具体来说，这个 xml 将包括：

Linearlayout<- orientation:veritcal
 <Button>
 <Listview>
 <Listview>
->

然后，此布局将在您的 setContentView 中使用，然后您可以检索该按钮，然后配置其代码以允许刷新您的 ListView。或者您可以将其添加到您的选项菜单中。

于 2012-08-04T14:34:38.813 回答
0 
enter code here
<?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">
<Button 
    android:id="@+id/refresh"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"/>
<ListView
    android:id="@+id/listpromo"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"/>

 </LinearLayout>

开始在您的活动中实施刷新代码。

enter code here
Button refresh= (Button)findviewById(R.id.refresh);
refresh.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

                       //Implement the List Adapter Code here to refresh the Content.
        }
    } );
于 2012-09-20T10:45:46.630 回答