Tamam, belki de Android dokümantasyonunda biraz fazla serttim, çünkü bazı yararlı bilgilere sahip, ama ne yazık ki hiçbiri ile bağlantılı değil setRetainInstance(). Gönderen parçaları hakkında sayfa
Not: Her parça, sistemin, etkinlik yeniden başlatılırsa parçayı geri yüklemek için kullanabileceği (ve bunu kaldırmak gibi işlemleri gerçekleştirmek için parçayı yakalamak için kullanabileceğiniz) benzersiz bir tanımlayıcı gerektirir. Bir parça için kimlik sağlamanın üç yolu vardır:
- Android: id özniteliğine benzersiz bir kimlik sağlayın.
- Android: tag niteliğini benzersiz bir dizeyle sağlayın.
- Önceki ikisinin hiçbirini sağlamazsanız, sistem konteyner görünümünün kimliğini kullanır.
Bu kuvvetle bunu yaparsanız ima setContentView(R.layout.whatever)içinde Activity.onCreated()ve bu düzen bir parçasını içerir setRetainInstance(true)etkinlik yine kendi kimliğini veya etiketini kullanarak aranacaktır yeniden edildiğinde sonra.
İkinci olarak, UI'sız parçalar için,
Kullanıcı arayüzü olmadan bir parça eklemek için, etkinlikten parçayı add (Parça, Dize) kullanarak ekleyin (parça için bir görünüm kimliği yerine benzersiz bir dize "etiketi" sağlayın). Bu, parçayı ekler, ancak etkinlik düzenindeki bir görünümle ilişkilendirilmediğinden, onCreateView () öğesine bir çağrı almaz. Yani bu yöntemi uygulamanıza gerek yok.
Ve dokümanlar çok iyi bir örneğe bağlantı veriyor - FragmentRetainInstance.java , size kolaylık sağlamak için aşağıda yeniden oluşturduğum . Sorumun cevabı olduğunu tahmin ettiğim şeyi yapıyor ( if (...findFragmentByTag() == null) { ...).
Son olarak, tam olarak hangi fonksiyonların çağrıldığını görmek için kendi test aktivitemi oluşturdum. Bunu, dikeyde başlayıp manzaraya döndürdüğünüzde çıkarır. Kod aşağıdadır.
(Okumayı kolaylaştırmak için biraz düzenlenmiştir.)
TestActivity@415a4a30: this()
TestActivity@415a4a30: onCreate()
TestActivity@415a4a30: Existing fragment not found.
TestFragment{41583008}: this() TestFragment{41583008}
TestFragment{41583008}: onAttach(TestActivity@415a4a30)
TestFragment{41583008}: onCreate()
TestFragment{41583008}: onCreateView()
TestFragment{41583008}: onActivityCreated()
TestActivity@415a4a30: onStart()
TestFragment{41583008}: onStart()
TestActivity@415a4a30: onResume()
TestFragment{41583008}: onResume()
<rotate device>
TestFragment{41583008}: onPause()
TestActivity@415a4a30: onPause()
TestFragment{41583008}: onStop()
TestActivity@415a4a30: onStop()
TestFragment{41583008}: onDestroyView()
TestFragment{41583008}: onDetach()
TestActivity@415a4a30: onDestroy()
TestActivity@415a3380: this()
TestFragment{41583008}: onAttach(TestActivity@415a3380)
TestActivity@415a3380: onCreate()
TestActivity@415a3380: Existing fragment found.
TestFragment{41583008}: onCreateView()
TestFragment{41583008}: onActivityCreated()
TestActivity@415a3380: onStart()
TestFragment{41583008}: onStart()
TestActivity@415a3380: onResume()
TestFragment{41583008}: onResume()
UI-az parçası: Not Android dokümantasyon yanlış olduğunu mu bir çağrı aldığınızda onCreateView()ama dönmek için serbesttir null.
TestActivity/ İçin kaynak koduTestFragment
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.concentriclivers.ss.R;
// An activity for understanding Android lifecycle events.
public class TestActivity extends Activity
{
private static final String TAG = TestActivity.class.getSimpleName();
public TestActivity()
{
super();
Log.d(TAG, this + ": this()");
}
protected void finalize() throws Throwable
{
super.finalize();
Log.d(TAG, this + ": finalize()");
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Log.d(TAG, this + ": onCreate()");
TextView tv = new TextView(this);
tv.setText("Hello world");
setContentView(tv);
if (getFragmentManager().findFragmentByTag("test_fragment") == null)
{
Log.d(TAG, this + ": Existing fragment not found.");
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.add(new TestFragment(), "test_fragment").commit();
}
else
{
Log.d(TAG, this + ": Existing fragment found.");
}
}
@Override
public void onStart()
{
super.onStart();
Log.d(TAG, this + ": onStart()");
}
@Override
public void onResume()
{
super.onResume();
Log.d(TAG, this + ": onResume()");
}
@Override
public void onPause()
{
super.onPause();
Log.d(TAG, this + ": onPause()");
}
@Override
public void onStop()
{
super.onStop();
Log.d(TAG, this + ": onStop()");
}
@Override
public void onDestroy()
{
super.onDestroy();
Log.d(TAG, this + ": onDestroy()");
}
public static class TestFragment extends Fragment
{
private static final String TAG = TestFragment.class.getSimpleName();
public TestFragment()
{
super();
Log.d(TAG, this + ": this() " + this);
}
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
Log.d(TAG, this + ": onCreate()");
setRetainInstance(true);
}
@Override
public void onAttach(final Activity activity)
{
super.onAttach(activity);
Log.d(TAG, this + ": onAttach(" + activity + ")");
}
@Override
public void onActivityCreated(Bundle savedInstanceState)
{
super.onActivityCreated(savedInstanceState);
Log.d(TAG, this + ": onActivityCreated()");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
Log.d(TAG, this + ": onCreateView()");
return null;
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState)
{
super.onViewCreated(view, savedInstanceState);
Log.d(TAG, this + ": onViewCreated()");
}
@Override
public void onDestroyView()
{
super.onDestroyView();
Log.d(TAG, this + ": onDestroyView()");
}
@Override
public void onDetach()
{
super.onDetach();
Log.d(TAG, this + ": onDetach()");
}
@Override
public void onStart()
{
super.onStart();
Log.d(TAG, this + ": onStart()");
}
@Override
public void onResume()
{
super.onResume();
Log.d(TAG, this + ": onResume()");
}
@Override
public void onPause()
{
super.onPause();
Log.d(TAG, this + ": onPause()");
}
@Override
public void onStop()
{
super.onStop();
Log.d(TAG, this + ": onStop()");
}
@Override
public void onDestroy()
{
super.onDestroy();
Log.d(TAG, this + ": onDestroy()");
}
}
}
Kaynak kodu FragmentRetainInstance.java(API 16'dan itibaren):
/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.example.android.apis.app;
import com.example.android.apis.R;
import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ProgressBar;
/**
* This example shows how you can use a Fragment to easily propagate state
* (such as threads) across activity instances when an activity needs to be
* restarted due to, for example, a configuration change. This is a lot
* easier than using the raw Activity.onRetainNonConfiguratinInstance() API.
*/
public class FragmentRetainInstance extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// First time init, create the UI.
if (savedInstanceState == null) {
getFragmentManager().beginTransaction().add(android.R.id.content,
new UiFragment()).commit();
}
}
/**
* This is a fragment showing UI that will be updated from work done
* in the retained fragment.
*/
public static class UiFragment extends Fragment {
RetainedFragment mWorkFragment;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.fragment_retain_instance, container, false);
// Watch for button clicks.
Button button = (Button)v.findViewById(R.id.restart);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
mWorkFragment.restart();
}
});
return v;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
FragmentManager fm = getFragmentManager();
// Check to see if we have retained the worker fragment.
mWorkFragment = (RetainedFragment)fm.findFragmentByTag("work");
// If not retained (or first time running), we need to create it.
if (mWorkFragment == null) {
mWorkFragment = new RetainedFragment();
// Tell it who it is working with.
mWorkFragment.setTargetFragment(this, 0);
fm.beginTransaction().add(mWorkFragment, "work").commit();
}
}
}
/**
* This is the Fragment implementation that will be retained across
* activity instances. It represents some ongoing work, here a thread
* we have that sits around incrementing a progress indicator.
*/
public static class RetainedFragment extends Fragment {
ProgressBar mProgressBar;
int mPosition;
boolean mReady = false;
boolean mQuiting = false;
/**
* This is the thread that will do our work. It sits in a loop running
* the progress up until it has reached the top, then stops and waits.
*/
final Thread mThread = new Thread() {
@Override
public void run() {
// We'll figure the real value out later.
int max = 10000;
// This thread runs almost forever.
while (true) {
// Update our shared state with the UI.
synchronized (this) {
// Our thread is stopped if the UI is not ready
// or it has completed its work.
while (!mReady || mPosition >= max) {
if (mQuiting) {
return;
}
try {
wait();
} catch (InterruptedException e) {
}
}
// Now update the progress. Note it is important that
// we touch the progress bar with the lock held, so it
// doesn't disappear on us.
mPosition++;
max = mProgressBar.getMax();
mProgressBar.setProgress(mPosition);
}
// Normally we would be doing some work, but put a kludge
// here to pretend like we are.
synchronized (this) {
try {
wait(50);
} catch (InterruptedException e) {
}
}
}
}
};
/**
* Fragment initialization. We way we want to be retained and
* start our thread.
*/
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Tell the framework to try to keep this fragment around
// during a configuration change.
setRetainInstance(true);
// Start up the worker thread.
mThread.start();
}
/**
* This is called when the Fragment's Activity is ready to go, after
* its content view has been installed; it is called both after
* the initial fragment creation and after the fragment is re-attached
* to a new activity.
*/
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
// Retrieve the progress bar from the target's view hierarchy.
mProgressBar = (ProgressBar)getTargetFragment().getView().findViewById(
R.id.progress_horizontal);
// We are ready for our thread to go.
synchronized (mThread) {
mReady = true;
mThread.notify();
}
}
/**
* This is called when the fragment is going away. It is NOT called
* when the fragment is being propagated between activity instances.
*/
@Override
public void onDestroy() {
// Make the thread go away.
synchronized (mThread) {
mReady = false;
mQuiting = true;
mThread.notify();
}
super.onDestroy();
}
/**
* This is called right before the fragment is detached from its
* current activity instance.
*/
@Override
public void onDetach() {
// This fragment is being detached from its activity. We need
// to make sure its thread is not going to touch any activity
// state after returning from this function.
synchronized (mThread) {
mProgressBar = null;
mReady = false;
mThread.notify();
}
super.onDetach();
}
/**
* API for our UI to restart the progress thread.
*/
public void restart() {
synchronized (mThread) {
mPosition = 0;
mThread.notify();
}
}
}
}