android startActivtyForResult以及ExpandableListActivity的使用

该程序实现 介绍如何启动Activity并获取被启动Activity返回的结果

1.MainActivity.java

public class ActivityForResult extends Activity
{
	Button bn;
	EditText city;	
	@Override
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		//获取界面上的组件
		bn = (Button)findViewById(R.id.bn);
		city = (EditText)findViewById(R.id.city);
		//为按钮绑定事件监听器
		bn.setOnClickListener(new OnClickListener()
		{
			@Override
			public void onClick(View source)
			{
				//创建需要对应于目标Activity的Intent
				Intent intent = new Intent(ActivityForResult.this
					, SelectCityActivity.class);
				//启动指定Activity并等待返回的结果，其中0是请求码，用于标识该请求
				startActivityForResult(intent , 0);
			}
		});
	}
	//重写该方法，该方法以回调的方式来获取指定Activity返回的结果
	@Override
	public void onActivityResult(int requestCode , int resultCode
		, Intent intent)
	{
		//当requestCode、resultCode同时为0，也就是处理特定的结果
		if (requestCode == 0
			&& resultCode == 0)
		{
			//取出Intent里的Extras数据
			Bundle data = intent.getExtras();
			//取出Bundle中的数据
			String resultCity = data.getString("city");
			//修改city文本框的内容
			city.setText(resultCity);
		}
	}
}

2.SelectCityActivity.java

public class SelectCityActivity extends ExpandableListActivity
{
	//定义省份数组
	private String[] provinces = new String[]
	{ "广东", "广西", "湖南"};
	private String[][] cities = new String[][]
	{
		{ "广州", "深圳", "珠海", "中山" },
		{ "桂林", "柳州", "南宁", "北海" },
		{ "长沙", "岳阳" , "衡阳" , "株洲" }
	};	
	public void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		ExpandableListAdapter adapter = new BaseExpandableListAdapter()
		{
			//获取指定组位置、指定子列表项处的子列表项数据
			@Override
			public Object getChild(int groupPosition, int childPosition)
			{
				return cities[groupPosition][childPosition];
			}
			@Override
			public long getChildId(int groupPosition, int childPosition)
			{
				return childPosition;
			}
			@Override
			public int getChildrenCount(int groupPosition)
			{
				return cities[groupPosition].length;
			}
			private TextView getTextView()
			{
				AbsListView.LayoutParams lp = new AbsListView.LayoutParams(
						ViewGroup.LayoutParams.FILL_PARENT, 64);
				TextView textView = new TextView(SelectCityActivity.this);
				textView.setLayoutParams(lp);
				textView.setGravity(Gravity.CENTER_VERTICAL | Gravity.LEFT);
				textView.setPadding(36, 0, 0, 0);
				textView.setTextSize(20);
				return textView;
			}
			//该方法决定每个子选项的外观
			@Override
			public View getChildView(int groupPosition, int childPosition,
					boolean isLastChild, View convertView, ViewGroup parent)
			{
				TextView textView = getTextView();			
				textView.setText(getChild(groupPosition, childPosition).toString());
				return textView;
			}
			//获取指定组位置处的组数据
			@Override
			public Object getGroup(int groupPosition)
			{
				return provinces[groupPosition];
			}
			@Override
			public int getGroupCount()
			{
				return provinces.length;
			}
			@Override
			public long getGroupId(int groupPosition)
			{
				return groupPosition;
			}
			//该方法决定每个组选项的外观
			@Override
			public View getGroupView(int groupPosition, boolean isExpanded,
					View convertView, ViewGroup parent)
			{
				LinearLayout ll = new LinearLayout(SelectCityActivity.this);
				ll.setOrientation(0);
				ImageView logo = new ImageView(SelectCityActivity.this);
				ll.addView(logo);
				TextView textView = getTextView();
				textView.setText(getGroup(groupPosition).toString());				
				ll.addView(textView);			
				return ll;
			}
			@Override
			public boolean isChildSelectable(int groupPosition, int childPosition)
			{
				return true;
			}
			@Override
			public boolean hasStableIds()
			{
				return true;
			}
		};
		// 设置该窗口显示列表
		setListAdapter(adapter);
		getExpandableListView().setOnChildClickListener(
			new OnChildClickListener()
		{
			@Override
			public boolean onChildClick(ExpandableListView parent, View source,
				int groupPosition, int childPosition, long id)
			{
				//获取启动该Activity之前的Activity对应的Intent
				Intent intent = getIntent();
				Bundle data = new Bundle();
				data.putString("city" ,cities[groupPosition][childPosition]);
				intent.putExtras(data);
				// 设置该SelectActivity的结果码，并设置结束之后退回的Activity
				SelectCityActivity.this.setResult(0 , intent);
				//结束SelectCityActivity。
				SelectCityActivity.this.finish();
				return false;
			}
		});
	}
}

3.效果