android - 我们如何在 android 的弹出窗口中添加一个 ExpandableListView？

Question

我正在创建一个示例 android 应用程序，其中当应用程序处于横向模式时，ExpandableListView 会显示在左侧。但是，当应用程序以纵向模式运行时，ExpandableListView 必须在单击 showpopup 按钮时显示为 PopupWindow。我们如何在 Android 的 PopupWindow 中添加一个 ExpandableListView？

我对 popupwindow 和 ExpandableListView 做了一些初步研究。这是我试过的代码(人像模式)

public class LoginActivity extends Activity
{

private Button                     btnShowPopUp;
private PopupWindow                mpopup;

ExpandableListAdapter              adapter;

private ExpandListAdapter          ExpAdapter;
private ArrayList<ExpandListGroup>  ExpListItems;
private ExpandableListView         ExpandList;

@Override
public void onCreate (Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    try
    {
        btnShowPopUp = (Button) findViewById(R.id.btnShowPopUp);

        btnShowPopUp.setOnClickListener(new OnClickListener()
        {
            public void onClick (View arg0)
            {
                    PopupwithExpndLst();
                //PopupwithBtn();

            }
        });
    }
    catch (Exception ex)
    {
        Log.i("Test", "Error is " + ex.getMessage());
    }

}

public void PopupwithExpndLst ()
{
    try
    {
         View popUpView = getLayoutInflater().inflate(R.layout.explist, null); // inflating popup layout

        mpopup = new PopupWindow(popUpView, LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT, true); // Creation of popup
        mpopup.setAnimationStyle(android.R.style.Animation_Dialog);
        mpopup.showAtLocation(popUpView, Gravity.BOTTOM, 0, 0); // Displaying popup

        ExpandList = (ExpandableListView) findViewById(R.id.lstExpList);
        adapter = new MyExpandableListAdapter(this);
        ExpandList.setAdapter(adapter);


    }
    catch (Exception ex)
    {
        Log.i("Test", "Error is " + ex.getMessage());
    }
}


public void PopupwithBtn ()
{
    View popUpView = getLayoutInflater().inflate(R.layout.popup, null); // inflating popup layout
    mpopup = new PopupWindow(popUpView, LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT, true); // Creation of popup
    mpopup.setAnimationStyle(android.R.style.Animation_Dialog);
    mpopup.showAtLocation(popUpView, Gravity.BOTTOM, 0, 0); // Displaying popup

    ExpandList = (ExpandableListView) findViewById(R.id.lstExpList);
    adapter = new MyExpandableListAdapter(this);
    ExpandList.setAdapter(adapter);

    Button btnOk = (Button) popUpView.findViewById(R.id.btnOk);
    btnOk.setOnClickListener(new OnClickListener()
    {
        public void onClick (View v)
        {
            mpopup.dismiss(); // dismissing the popup
        }
    });

    Button btnCancel = (Button) popUpView.findViewById(R.id.btnCancel);
    btnCancel.setOnClickListener(new OnClickListener()
    {
        public void onClick (View v)
        {
            mpopup.dismiss(); // dismissing the popup
        }
    });
}

public ArrayList<ExpandListGroup> SetStandardGroups ()
{
    ArrayList<ExpandListGroup> list = new ArrayList<ExpandListGroup>();
    ArrayList<ExpandListChild> list2 = new ArrayList<ExpandListChild>();
    ExpandListGroup gru1 = new ExpandListGroup();
    gru1.setName("Comedy");
    ExpandListChild ch1_1 = new ExpandListChild();
    ch1_1.setName("A movie");
    ch1_1.setTag(null);
    list2.add(ch1_1);
    ExpandListChild ch1_2 = new ExpandListChild();
    ch1_2.setName("An other movie");
    ch1_2.setTag(null);
    list2.add(ch1_2);
    ExpandListChild ch1_3 = new ExpandListChild();
    ch1_3.setName("And an other movie");
    ch1_3.setTag(null);
    list2.add(ch1_3);
    gru1.setItems(list2);
    list2 = new ArrayList<ExpandListChild>();

    ExpandListGroup gru2 = new ExpandListGroup();
    gru2.setName("Action");
    ExpandListChild ch2_1 = new ExpandListChild();
    ch2_1.setName("A movie");
    ch2_1.setTag(null);
    list2.add(ch2_1);
    ExpandListChild ch2_2 = new ExpandListChild();
    ch2_2.setName("An other movie");
    ch2_2.setTag(null);
    list2.add(ch2_2);
    ExpandListChild ch2_3 = new ExpandListChild();
    ch2_3.setName("And an other movie");
    ch2_3.setTag(null);
    list2.add(ch2_3);
    gru2.setItems(list2);
    list.add(gru1);
    list.add(gru2);

    return list;
}

@Override
public boolean onCreateOptionsMenu (Menu menu)
{
    getMenuInflater().inflate(R.menu.activity_login, menu);
    return true;
}

我的ActivityLogin.xml是

    <?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/btnShowPopUp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="ShowPopUp" >
</Button>

</LinearLayout>

我的explist.xml是

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#90FFFFFF"
android:orientation="vertical" >

<TextView
    android:id="@+id/txtEmpty"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:text="No items" />

<ExpandableListView
    android:id="@+id/lstExpList"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:groupIndicator="@null" />

popup.xml 是

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#90FFFFFF"
android:orientation="vertical" >

<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:gravity="center"
    android:text="PopUp Window"
    android:textColor="#000000"
    android:textStyle="bold" >
</TextView>

<Button
    android:id="@+id/btnOk"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Ok" >
</Button>

<Button
    android:id="@+id/btnCancel"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Cancel" >
</Button>

我的 ExpendableListAdapter.java 是

    public class ExpandListAdapter extends BaseExpandableListAdapter
    {

private Context                    context;
private ArrayList<ExpandListGroup>  groups;

public ExpandListAdapter(Context context, ArrayList<ExpandListGroup> groups)
{
    try
    {

        this.context = context;
        this.groups = groups;

    }
    catch (Exception ex)
    {
        Log.i("Test", "Error is " + ex.getMessage());
    }
}

public void addItem (ExpandListChild item, ExpandListGroup group)
{
    if (!groups.contains(group))
    {
        groups.add(group);
    }
    int index = groups.indexOf(group);
    ArrayList<ExpandListChild> ch = groups.get(index).getItems();
    ch.add(item);
    groups.get(index).setItems(ch);
}

public Object getChild (int groupPosition, int childPosition)
{
    ArrayList<ExpandListChild> chList = groups.get(groupPosition).getItems();
    return chList.get(childPosition);
}

public long getChildId (int groupPosition, int childPosition)
{

    return childPosition;
}

public View getChildView (int groupPosition, int childPosition, boolean isLastChild, View view, ViewGroup parent)
{
    ExpandListChild child = (ExpandListChild) getChild(groupPosition, childPosition);
    if (view == null)
    {
        LayoutInflater inflater = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);

        view = inflater.inflate(R.layout.expandlist_child_item, null);
    }
    TextView tv = (TextView) view.findViewById(R.id.tvChild);
    tv.setText(child.getName().toString());
    tv.setTag(child.getTag());

    return view;
}

public int getChildrenCount (int groupPosition)
{
    // TODO Auto-generated method stub
    ArrayList<ExpandListChild> chList = groups.get(groupPosition).getItems();
    return chList.size();
}

public Object getGroup (int groupPosition)
{
    // TODO Auto-generated method stub

    return groups.get(groupPosition);
}

public int getGroupCount ()
{
    // TODO Auto-generated method stub
    return groups.size();
}

public long getGroupId (int groupPosition)
{
    // TODO Auto-generated method stub
    return groupPosition;
}

public View getGroupView (int groupPosition, boolean isLastChild, View view, ViewGroup parent)
{
    // TODO Auto-generated method stub
    ExpandListGroup group = (ExpandListGroup) getGroup(groupPosition);
    if (view == null)
    {
        LayoutInflater inf = (LayoutInflater) context.getSystemService(context.LAYOUT_INFLATER_SERVICE);
        view = inf.inflate(R.layout.expamdlist_group_item, null);

    }
    TextView tv = (TextView) view.findViewById(R.id.tvGroup);
    tv.setText(group.getName());
    return view;
}

public boolean hasStableIds ()
{
    // TODO Auto-generated method stub
    return true;
}

public boolean isChildSelectable (int groupPosition, int childPosition)
{
    // TODO Auto-generated method stub
    return true;
}

在 LoginActivity 类中，如果我在 btnShowpopup 的 onclick 方法中使用 PopupwithBtn() 函数，弹出窗口会按预期工作，但是当我使用 PopupwithExpndLst() 时。

在 PopupwithExpndLst() 方法中，当我尝试为可扩展列表设置适配器时，它显示空指针异常。请帮助我解决问题。

提前致谢宾泽

Answer 1

好的，我刚弄清楚问题

我一定用过

    (ExpandableListView) mpopup.getContentView().findViewById(R.id.lstExpList)

代替

    (ExpandableListView)findViewById(R.id.lstExpList)

在 PopupwithExpndLst() 方法中

希望对大家有所帮助

谢谢