java - 使用CompoundDrawable的ExpandableListView的CustomAdapter

Question

要有耐心，因为我刚刚学习，而且我是新手。我无法弄清楚如何在以下代码中为每个子项设置不同的 CompoundDrawable 。

这是我的Activity和CustomAdapter

import android.graphics.drawable.Drawable;
import android.os.DropBoxManager;
import android.support.annotation.DrawableRes;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ExpandableListView;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class MainActivity extends AppCompatActivity {

private ExpandableListAdapter listAdapter;
private ExpandableListView expListView;
private List<String> listDataHeader;
private HashMap<String, List<String>> listDataChild;



@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


    // get the listview
    expListView = (ExpandableListView) findViewById(R.id.lvExp);


    // preparing list data
    prepareListData();

    listAdapter = new ExpandableListAdapter(this, listDataHeader, listDataChild);

    // setting list adapter
    expListView.setAdapter(listAdapter);
}



/*
     * Preparing the list data
     */
private void prepareListData() {
    listDataHeader = new ArrayList<String>();
    listDataChild = new HashMap<String, List<String>>();


    // Adding child data
    listDataHeader.add("NATIONS");



    // Adding child data
    List<String> NATIONS = new ArrayList<String>();
    NATIONS.add("AUSTRALIA");
    NATIONS.add("AUSTRIA");
    NATIONS.add("BELGIO");
    NATIONS.add("BRASILE");
    NATIONS.add("BULGARIA");
    NATIONS.add("CANADA");
    NATIONS.add("CILE");
    NATIONS.add("CINA");
    NATIONS.add("COLOMBIA");
    NATIONS.add("CUBA");
    NATIONS.add("ITALIA");


    listDataChild.put(listDataHeader.get(0), NATIONS);// Header, Child data


    }

}

现在我应该初始化一个CompoundDrawable数组吗？我做到了，但我不知道如何将其添加到创建的 HashMap

和适配器

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import android.content.Context;
import android.graphics.Typeface;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.InsetDrawable;
import android.media.Image;
import android.support.annotation.DrawableRes;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

import org.w3c.dom.NodeList;

public class ExpandableListAdapter extends BaseExpandableListAdapter {


private Context _context;
private List<String> _listDataHeader; // header titles


// child data in format of header title, child title
private HashMap<String, List<String>> _listDataChild;

public ExpandableListAdapter(Context context, List<String> listDataHeader,
                             HashMap<String, List<String>> listChildData) {
    this._context = context;
    this._listDataHeader = listDataHeader;
    this._listDataChild = listChildData;

}

@Override
public Object getChild(int groupPosition, int childPosititon) {
    return this._listDataChild.get(this._listDataHeader.get(groupPosition))
            .get(childPosititon);
}

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


@Override
public View getChildView(int groupPosition, final int childPosition,
                         boolean isLastChild, View convertView, ViewGroup   parent) {

    final String childText = (String) getChild(groupPosition, childPosition);

    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_item, null);
    }


    TextView txtListChild = (TextView) convertView.findViewById(R.id.lblListItem);
    txtListChild.setText(childText);

// From this point i would like to set the Compound Drawable DIFFERENT for each childText.

    return convertView;
}



@Override
public int getChildrenCount(int groupPosition) {
    return this._listDataChild.get(this._listDataHeader.get(groupPosition))
            .size();

}

@Override
public Object getGroup(int groupPosition) {
    return this._listDataHeader.get(groupPosition);
}

@Override
public int getGroupCount() {
    return this._listDataHeader.size();
}

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

@Override
public View getGroupView(int groupPosition, boolean isExpanded,
                         View convertView, ViewGroup parent) {
    String headerTitle = (String) getGroup(groupPosition);
    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_group, null);
    }

    TextView lblListHeader = (TextView) convertView.findViewById(R.id.lblListHeader);
    lblListHeader.setTypeface(null, Typeface.BOLD);
    lblListHeader.setText(headerTitle);
    return convertView;
}

@Override
public boolean hasStableIds() {
    return false;
}

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

Answer 1

您可以添加 ListDataChild 列表，而不是将字符串列表添加到 map 中，其中 ListDataChild 是您必须创建的类，如下所示:

public class ListDataChild {
    public String text;
    public Drawable drawable;

    public ListDataChild() {}

    public ListDataChild(String text, Drawable drawable) {
        this.text = text;
        this.drawable = drawable;
    } 
}

然后在你的“prepareListData()”方法中

private void prepareListData() {
    listDataHeader = new ArrayList<String>();
    listDataChild = new HashMap<String, List<ListDataChild>>();

    // Adding child data
    listDataHeader.add("NATIONS");

    // Adding child data
    Drawable[] drawables = ... //An array of preloaded Drawables
    List<ListDataChild> NATIONS = new ArrayList<ListDataChild>();
    NATIONS.add(new ListDataChild("AUSTRALIA", drawables[0]));
    NATIONS.add(new ListDataChild("AUSTRIA", drawables[1]));
    NATIONS.add(new ListDataChild("BELGIO", drawables[2]));
    NATIONS.add(new ListDataChild("BRASILE", drawables[3]));
    NATIONS.add(new ListDataChild("BULGARIA", drawables[4]));
    NATIONS.add(new ListDataChild("CANADA", drawables[5]));
    NATIONS.add(new ListDataChild("CILE", drawables[6]));
    NATIONS.add(new ListDataChild("CINA", drawables[7]));
    NATIONS.add(new ListDataChild("COLOMBIA", drawables[8]));
    NATIONS.add(new ListDataChild("CUBA", drawables[9]));
    NATIONS.add(new ListDataChild("ITALIA", drawables[10]));


    listDataChild.put(listDataHeader.get(0), NATIONS);// Header, Child data

}

然后更改 Adapter 类中的一些代码行

// child data in format of header title, child title
private HashMap<String, List<ListDataChild>> _listDataChild;

public ExpandableListAdapter(Context context, List<String> listDataHeader,
                         HashMap<String, List<ListDataChild>> listChildData) {
    this._context = context;
    this._listDataHeader = listDataHeader;
    this._listDataChild = listChildData;

}

最后，当您设置 subview 时，您可以执行类似的操作

@Override
public View getChildView(int groupPosition, final int childPosition,
                         boolean isLastChild, View convertView, ViewGroup   parent) {

    final ListDataChild child = (ListDataChild) getChild(groupPosition, childPosition);

    if (convertView == null) {
        LayoutInflater infalInflater = (LayoutInflater) this._context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = infalInflater.inflate(R.layout.list_item, null);
    }


    TextView txtListChild = (TextView) convertView.findViewById(R.id.lblListItem);

    //Set The TextView text
    txtListChild.setText(child.text);

    //Set left drawable
    txtListChild.setCompoundDrawables(child.drawable, null, null, null); 

    return convertView;
}

无论如何，我认为将 Drawable 保存到 Map 中并不是最好的选择(因为内存使用)。您可以保存可绘制对象的 id，然后在需要时加载可绘制对象。所以ListDataChild就变成这样了

public class ListDataChild {
    public String text;
    public int drawableId;

    public ListDataChild() {}

    public ListDataChild(String text, int drawableId) {
        this.text = text;
        this.drawableId = drawableId;
    }
}

当您需要 Drawable 时，您可以加载它:

ListDataChild child = ... //Your data child object
Drawable drawable = ContextCompat.getDrawable(context, child.drawableId);