android ListView显示和隐藏二级内容

android中，使用ListView时，有时候发现每一个item内容比较多，无法一次性全显示。这时需要把重点内容显示，其他内容隐藏起来，点击某一项时才弹出详细信息。本工程实现了以上功能点，希望有所帮助！

/** Automatically generated file. DO NOT MODIFY */
package com.example.dropdownlist;

public final class BuildConfig {
    public final static boolean DEBUG = true;
}

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2015-01-18 20:33  DropDownList\
     文件         364  2015-01-18 20:33  DropDownList\.classpath
     文件         848  2015-01-18 20:33  DropDownList\.project
     文件         888  2015-01-18 20:33  DropDownList\AndroidManifest.xml
     目录           0  2015-01-19 22:24  DropDownList\assets\
     目录           0  2015-01-19 22:24  DropDownList\bin\
     文件         888  2015-01-19 22:24  DropDownList\bin\AndroidManifest.xml
     目录           0  2015-01-19 22:24  DropDownList\bin\classes\
     目录           0  2015-01-19 22:24  DropDownList\bin\classes\com\
     目录           0  2015-01-19 22:24  DropDownList\bin\classes\com\example\
     目录           0  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\
     文件         357  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\BuildConfig.class
     文件         355  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\ListItem.class
     文件        2037  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\MainActivity.class
     文件        1511  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\MyAdapter$1.class
     文件        1391  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\MyAdapter$2.class
     文件        1391  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\MyAdapter$3.class
     文件        1391  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\MyAdapter$4.class
     文件        4129  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\MyAdapter.class
     文件         358  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$attr.class
     文件         522  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$color.class
     文件         671  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$drawable.class
     文件         705  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$id.class
     文件         454  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$layout.class
     文件         415  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$menu.class
     文件         581  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$string.class
     文件         449  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R$style.class
     文件         733  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\R.class
     文件         560  2015-01-19 22:24  DropDownList\bin\classes\com\example\dropdownlist\ViewHolder.class
     目录           0  2015-01-19 22:24  DropDownList\bin\res\
     目录           0  2015-01-19 22:24  DropDownList\gen\
............此处省略48个文件信息