Android组件学习之ExpandableListView

一个简单的小例子：

可以展开的ListView，和Listview差不多，只是设置的Adapter不同。常用的Adapter有BaseExpandableListAdapter、SimpleExpandableListAdapter、SimpleCursorTreeAdapter

布局如下：(布局中我设置了android:groupIndicator，不知道为什么不起作用。另外，android:dividerHeight这个属性是组对象和子节点共用的。如果要定义比较复杂的组视图及子节点视图，还是单独设置一个layout文件，再在Adapter中设置相应的返回View视图)

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.testandroid.ui.MainActivity" >

    <ExpandableListView
        android:id="@+id/main_elv1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:childDivider="@color/white"
        android:divider="@color/gray"
        android:dividerHeight="1px"
        android:groupIndicator="@drawable/arrow_triangle_down"
        android:indicatorLeft="4dp"
        android:indicatorRight="4dp" >
    </ExpandableListView>

</RelativeLayout>

主Activity如下：

package com.example.testandroid.ui;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ExpandableListView;

import com.example.testandroid.R;
import com.example.testandroid.adapter.MainActivityExLVAdapter;

public class MainActivity extends ActionBarActivity {

    private ExpandableListView mExpandableListView = null;
    private MainActivityExLVAdapter mMainActivityExLVAdapter = null;

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

    private void init() {
        mExpandableListView = (ExpandableListView) findViewById(R.id.main_elv1);
        mMainActivityExLVAdapter = new MainActivityExLVAdapter(this);
        mExpandableListView.setAdapter(mMainActivityExLVAdapter);
    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

Adapter我写到另外一个类文件中：

package com.example.testandroid.adapter;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseExpandableListAdapter;
import android.widget.TextView;

public class MainActivityExLVAdapter extends BaseExpandableListAdapter {

    private Context mContext = null;

    private String[] mGroup = { "FirstOne", "SecondTwo", "ThirdThress" };
    private String[][] mChildren = {
            { "2014-year-01-month-01", "2014-year-01-month-02",
                    "2014-year-01-month-03", "2014-year-01-month-04",
                    "2014-year-01-month-05" },
            { "2014-year-02-month-01", "2014-year-02-month-02",
                    "2014-year-02-month-03", "2014-year-02-month-04" },
            { "2014-year-03-month-01", "2014-year-03-month-02", } };

    public MainActivityExLVAdapter(Context mContext) {
        this.mContext = mContext;
    }

    /**
     * 获取组的数量
     */
    @Override
    public int getGroupCount() {
        return mGroup.length;
    }

    /**
     * 获取组下的节点数量
     */
    @Override
    public int getChildrenCount(int groupPosition) {
        return mChildren[groupPosition].length;
    }

    /**
     * 获取组对象(这个方法可以返回任意对象，或者null都行，给自己调用的)
     */
    @Override
    public Object getGroup(int groupPosition) {
        return mGroup[groupPosition];
    }

    /**
     * 获取子节点对象(这个方法可以返回任意对象，或者null都行，给自己调用的)
     */
    @Override
    public Object getChild(int groupPosition, int childPosition) {
        return mChildren[groupPosition][childPosition];
    }

    /**
     * 给自己调用的
     */
    @Override
    public long getGroupId(int groupPosition) {
        return groupPosition;
    }

    /**
     * 给自己调用的
     */
    @Override
    public long getChildId(int groupPosition, int childPosition) {
        return childPosition;
    }

    /**
     * TODO 不知道有什么用
     */
    @Override
    public boolean hasStableIds() {
        return true;
    }

    /**
     * 返回组对象的视图
     */
    @Override
    public View getGroupView(int groupPosition, boolean isExpanded,
            View convertView, ViewGroup parent) {
        TextView mTextView = new TextView(mContext);
        mTextView.setText(getGroup(groupPosition).toString());
        return mTextView;
    }

    /**
     * 返回子节点的视图
     */
    @Override
    public View getChildView(int groupPosition, int childPosition,
            boolean isLastChild, View convertView, ViewGroup parent) {
        TextView mTextView = new TextView(mContext);
        mTextView.setText(getChild(groupPosition, childPosition).toString());
        return mTextView;
    }

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

}