startActivityForResult()

可以调用多个startActivityForResult(Intent, int requestCode)打开新的activity来处理业务

当这些新的activiy关闭后会调用onActivityResult处理返回结果，利用requestCode可以辨别

是什么业务请求所触发的

setResult(int resultCode, Intent data)

onActivityResult(int requestCode, int resultCode, Intent data)

public class MainActivity 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(MainActivity.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时，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);
}
}
}

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.MATCH_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(LinearLayout.HORIZONTAL);
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();
intent.putExtra("city",
cities[groupPosition][childPosition]);
// 设置该SelectCityActivity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;
}
});
}
}