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[英]How to pass value from parent activity to child activity and on child activity exit, refresh the parent activity
[英]Refreshing parent activity from child?
伙計們,我是Java android編程的新手(這是我正在制作的第一個應用程序),我有一個問題:如何從另一個活動(從主要活動中調用)刷新我的主要活動? 如果您給我一些例子,我也將不勝感激,因為我仍然不太適應...
您可以為此目的使用startActivityForResult()
,而不是context.startActivity()
調用context.startActivityForResult()
,然后在完成活動之前在啟動的活動中設置結果。
這是Context.startActivityForResult()
的文檔
樣例代碼:
// Activity A
public class ActivityA extends Activity {
private static final int REQUEST_CODE_ACTIVITY_B_FOR_RESULT = 1; // or other int value
// sample code which starts Activity B
private void onSomeButtonClick() {
Intent intent = new Intent(this, ActivityB.class);
startActivityForResult(intent, REQUEST_CODE_ACTIVITY_B_FOR_RESULT);
}
// this method will be called when started activity finished
// and returned some result of its work
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent resultData) {
super.onActivityResult(requestCode, resultCode, resultData);
if (requestCode == REQUEST_CODE_ACTIVITY_B_FOR_RESULT) {
if (resultCode == RESULT_OK) {
// handle result ok and resultData here
} else {
// handle result canceled or other resultCode and its resultData here
}
}
}
}
// Activity B
public class ActivityB extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setResult(RESULT_CANCELED); // by default result of starting activity is negative
}
// some code which doing some action and setting result as ok
private void doSomething() {
Intent resultData = new Intent();
resultData.putExtra("SOME_EXTRA", "did it"); // or other result data
setResult(RESULT_OK, resultData);
finish(); // finishing this activity, result code and result data will be accessible in previous activity
}
}
如何從子活動中調用主要活動。 使用界面。
1.在子活動中創建公共接口
public class MapSettings extends DialogFragment implements
OnCheckedChangeListener {
public interface BestRidesSettingsDialogListener {
void onMapSettingsChange(int mapType);
}
2.在主要活動注釋中實現界面,右鍵單擊錯誤,然后選擇添加導入,添加引用,添加未實現的方法。
public class KmlReader extends ActionBarActivity implements
BestRidesSettingsDialogListener {
3.當子活動開始時,在子活動中將getActivity強制轉換為公共接口
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// the activity may be null if this is called without implementing the
// BestRidesSettingsDialogListener (The settings object saves the
// setting so the
// call back may not be needed.
activity = (BestRidesSettingsDialogListener) getActivity();
4.然后在子活動中,單擊按鈕或發生某些事件時,調用接口方法。
@Override
public void onCheckedChanged(RadioGroup rg, int checkId) {
// TODO Auto-generated method stub
int mapType = 0;
switch (checkId) {
case R.id.RDORoad:
mapType = GoogleMap.MAP_TYPE_NORMAL;
break;
case R.id.RDOHybrid:
mapType = GoogleMap.MAP_TYPE_HYBRID;
break;
case R.id.RDOSatelite:
mapType = GoogleMap.MAP_TYPE_SATELLITE;
break;
case R.id.RDOTerrain:
mapType = GoogleMap.MAP_TYPE_TERRAIN;
break;
}
// run the activity onchange
// if the activity is null there is no listener to take action on the
// settings
if (activity != null) {
activity.onMapSettingsChange(mapType);
}
5.如果您已在主活動中填寫了未實現的方法存根,則直接在子活動中的主活動中執行代碼。
@Override
public void onMapSettingsChange(int mapType) {
if (mMap != null) {
mMap.setMapType(mapType);
}
}
注釋邊欄:接口一直是我最喜歡的Java部分。 您可以將其稱為偵聽器或回叫。 只需右鍵單擊錯誤並選擇添加引用,添加未實現的方法,實際上並沒有太多的擊鍵操作。 該界面也許是協調團隊工作的下一個重大任務的最簡單方法。
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