Question

我试图从Android developer开始运行示例。我正在使用第二个示例类。

从行：

       TextView textView = new TextView(ExpandableList1.this);

我在eclipse中收到以下错误：

       ExpandableList01 cannot be resolved to a type

我真的是一个初学者，并且已经很难设法制作一个超级简单的可扩展列表视图，但我没有得到任何地方。任何人吗？

导致错误的代码块：

   public TextView getGenericView() {
        // Layout parameters for the ExpandableListView
        AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT, 64);

        TextView textView = new TextView(ExpandableList1.this);
        textView.setLayoutParams(lp);
        // Center the text vertically
        textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
        // Set the text starting position
        textView.setPadding(36, 0, 0, 0);
        return textView;
    }

编辑，更多代码..

ExpandableList1.java：

package com.test.exlist;

import android.app.ExpandableListActivity;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.BaseExpandableListAdapter;
import android.widget.ExpandableListAdapter;
import android.widget.ExpandableListView;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.ExpandableListView.ExpandableListContextMenuInfo;

//import com.example.android.apis.R;


public class ExpandableList1 extends ExpandableListActivity {

    ExpandableListAdapter mAdapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Set up our adapter
        mAdapter = new MyExpandableListAdapter();
        setListAdapter(mAdapter);
        registerForContextMenu(getExpandableListView());
    }

    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
        menu.setHeaderTitle("Sample menu");
        menu.add(0, 0, 0, R.string.expandable_list_sample_action);
    }

    @Override
    public boolean onContextItemSelected(MenuItem item) {
        ExpandableListContextMenuInfo info = (ExpandableListContextMenuInfo) item.getMenuInfo();

        String title = ((TextView) info.targetView).getText().toString();

        int type = ExpandableListView.getPackedPositionType(info.packedPosition);
        if (type == ExpandableListView.PACKED_POSITION_TYPE_CHILD) {
            int groupPos = ExpandableListView.getPackedPositionGroup(info.packedPosition); 
            int childPos = ExpandableListView.getPackedPositionChild(info.packedPosition); 
            Toast.makeText(this, title + ": Child " + childPos + " clicked in group " + groupPos,
                    Toast.LENGTH_SHORT).show();
            return true;
        } else if (type == ExpandableListView.PACKED_POSITION_TYPE_GROUP) {
            int groupPos = ExpandableListView.getPackedPositionGroup(info.packedPosition); 
            Toast.makeText(this, title + ": Group " + groupPos + " clicked", Toast.LENGTH_SHORT).show();
            return true;
        }

        return false;
    }
}

MyExpandableListAdapter.java：

package com.test.exlist;    

import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

import com.test.exlist.ExpandableList1;


public class MyExpandableListAdapter extends BaseExpandableListAdapter {
        // Sample data set.  children[i] contains the children (String[]) for groups[i].
        private String[] groups = { "People Names", "Dog Names", "Cat Names", "Fish Names" };
        private String[][] children = {
                { "Arnold", "Barry", "Chuck", "David" },
                { "Ace", "Bandit", "Cha-Cha", "Deuce" },
                { "Fluffy", "Snuggles" },
                { "Goldy", "Bubbles" }
        };

        public Object getChild(int groupPosition, int childPosition) {
            return children[groupPosition][childPosition];
        }

        public long getChildId(int groupPosition, int childPosition) {
            return childPosition;
        }

        public int getChildrenCount(int groupPosition) {
            return children[groupPosition].length;
        }

        public TextView getGenericView() {
            // Layout parameters for the ExpandableListView
            AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
                    ViewGroup.LayoutParams.MATCH_PARENT, 64);

            TextView textView = new TextView(ExpandableList1.this);
            textView.setLayoutParams(lp);
            // Center the text vertically
            textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
            // Set the text starting position
            textView.setPadding(36, 0, 0, 0);
            return textView;
        }

        public View getChildView(int groupPosition, int childPosition, boolean isLastChild,
                View convertView, ViewGroup parent) {
            TextView textView = getGenericView();
            textView.setText(getChild(groupPosition, childPosition).toString());
            return textView;
        }

        public Object getGroup(int groupPosition) {
            return groups[groupPosition];
        }

        public int getGroupCount() {
            return groups.length;
        }

        public long getGroupId(int groupPosition) {
            return groupPosition;
        }

        public View getGroupView(int groupPosition, boolean isExpanded, View convertView,
                ViewGroup parent) {
            TextView textView = getGenericView();
            textView.setText(getGroup(groupPosition).toString());
            return textView;
        }

        public boolean isChildSelectable(int groupPosition, int childPosition) {
            return true;
        }

        public boolean hasStableIds() {
            return true;
        }

}

Answer 1

好的，你所做的是从示例文档中获取getGenericView（）方法，在该场景中使用“this”关键字将起作用，因为“this”指的是Activity的上下文（例）。

绑定到适配器的最佳方法是膨胀视图（在xml中定义）。这样，Android就会为您处理。

以下是我的一个适配器的getView方法示例：

@Override
public View getView(int position, View convertview, ViewGroup parent) {
    View v = convertview;
    final NoteInformationItemEntity e = (NoteInformationItemEntity) getItem(position);

    if (v == null) {
        LayoutInflater vi = (LayoutInflater) mContext
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        v = vi.inflate(R.layout.reminder_item, null);
    }

    ImageView img = (ImageView)v.findViewById(R.id.reminder_item_imgIcon);
    TextView txtTitle = (TextView)v.findViewById(R.id.reminder_item_txtTitle);
    TextView txtMainDescription = (TextView)v.findViewById(R.id.reminder_item_txtMainDescription);
    TextView txtSubDescription = (TextView)v.findViewById(R.id.reminder_item_txtSubDescription);

    img.setImageDrawable(mContext.getResources().getDrawable(e.getImageResourceID()));
    txtTitle.setText(e.getTitle());
    txtMainDescription.setText(Html.fromHtml(e.getMainDescription()));
    txtSubDescription.setText(Html.fromHtml(e.getSubDescription()));

    return v;
}

R.layout.reminder_item是布局目录中的xml文件。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content" android:background="@drawable/list_item_styled_9"
android:layout_width="fill_parent">
<ImageView android:layout_width="wrap_content"
    android:layout_height="wrap_content" android:layout_margin="5dip"
    android:id="@+id/reminder_item_imgIcon"></ImageView>
<LinearLayout android:layout_height="wrap_content"
    android:orientation="vertical" android:layout_width="fill_parent">
    <LinearLayout android:layout_height="wrap_content"
        android:layout_width="fill_parent" android:layout_weight="1"
        android:orientation="horizontal">
        <TextView android:layout_height="wrap_content"
            android:id="@+id/reminder_item_txtTitle" style="@style/ReminderListTitle"
            android:layout_width="wrap_content" android:layout_weight="1"></TextView>
    </LinearLayout>
    <LinearLayout android:layout_height="wrap_content"
        android:layout_width="fill_parent" android:layout_weight="1"
        android:orientation="vertical">
        <TextView android:layout_height="wrap_content"
            android:layout_width="fill_parent" android:layout_weight="1"
            android:id="@+id/reminder_item_txtMainDescription" style="@style/ReminderListText"></TextView>
        <TextView android:layout_height="wrap_content"
            android:layout_width="fill_parent" android:layout_weight="1"
            android:id="@+id/reminder_item_txtSubDescription" style="@style/ReminderListText"></TextView>
    </LinearLayout>
</LinearLayout>

我将上下文和我的数据传递给构造函数中的适配器：

Context mContext;
ArrayList<NoteInformationItemEntity> data;

public NoteListViewItemAdapter(Context context, ArrayList<NoteInformationItemEntity> _data)
{
    mContext = context;
    data = _data;
}

如果您不想像上面的示例那样夸大视图，可以使用该上下文来创建TextView

public TextView getGenericView() {
    // Layout parameters for the ExpandableListView
    AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
            ViewGroup.LayoutParams.MATCH_PARENT, 64);

    TextView textView = new TextView(mContext);
    textView.setLayoutParams(lp);
    // Center the text vertically
    textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
    // Set the text starting position
}

Answer 2

如果TextView位于Activity上，您可以使用以下代码：

TextView textView = new TextView(this);

如果您在活动之外创建它，则需要为其提供一个上下文，可能类似于：

public class UIHelper
{
    private Context mContext;

    public UIHelper(Context context)
    {
        mContext = context;
    }

    public TextView getGenericView() {

            TextView textView = new TextView(mContext);
            //Do your other stuff here
            return textView;
    }
}

您将从以下活动中调用它：

UIHelper u = new UIHelper(this);
TextView txt = u.getGenericView();

Android expandablelist，例如，错误

2 个答案: