Activity在onDestroy后无法恢复数据

3

我在两个ActionBarActivities中遇到了问题。 我有第一个Activity(WorkoutEditActivity),它从WorkoutEditActivity中的Fragment使用startActivityForResult启动另一个Activity(A2)。 当我按下A2的ActionBar上的Back按钮时,我的第一个Activity被销毁,并在保存数据后通过onSaveInstanceState重新启动Activity,但是我无法弄清楚如何恢复数据。 这是相关的代码,但不起作用:

    public class WorkoutEditActivity extends ActionBarActivity{
        int whatShouldBeSaved = -1;

        Workout workout = null;
        ViewPager viewpager;
        ViewFactory factory = new ViewFactory(getSupportFragmentManager());;

        @Override
        public void onCreate(Bundle savedInstanceState) {
        Log.d("onCreate", "called");
        super.onCreate(savedInstanceState);

        setContentView(R.layout.workout_edit_activity);

        viewpager = (ViewPager) findViewById(R.id.viewPager);
        viewpager.setOffscreenPageLimit(0);
        viewpager.setAdapter(factory);

        viewpager.setOnPageChangeListener(
                new ViewPager.OnPageChangeListener() {
                    @Override
                    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

                    }

                    @Override
                    public void onPageSelected(int position) {
                        if (position == 0) {
                            SettingsFragment.isActivated = true;
                        } else {
                            if (SettingsFragment.isActivated) {
                                SettingsFragment.isActivated = false;
                                InputMethodManager imm = (InputMethodManager) getSystemService(Activity.INPUT_METHOD_SERVICE);
                                imm.toggleSoftInput(InputMethodManager.HIDE_IMPLICIT_ONLY, 0);
                            }
                        }
                    }

                    @Override
                    public void onPageScrollStateChanged(int state) {

                    }
                }
        );

        if (savedInstanceState != null) {
            whatShouldBeSaved = savedInstanceState.getInt("test", -1);
            if (savedInstanceState.getSerializable("workout") != null){
                setWorkout((Workout) savedInstanceState.getSerializable("workout"));
            }
            Log.d("GOT SAVED DATA", "" + whatShouldBeSaved);
        }
        Log.d("CREATE", "created? " + workout);
        Log.d("CREATE", "created? " + whatShouldBeSaved);
        }

        public void setWorkout(Workout w){
        Log.d("WORKOUT", "had workout " + workout);
        workout = w;
        factory.setWorkout(workout);
        Log.d("WORKOUT", "has workout " + workout);
        }

        @Override
        public void onResume() {
        super.onResume();
        Log.d("RESUME", "resuming act");

        SettingsFragment.isActivated = true;
        //factory.setViewPager(viewpager);

        if (getIntent().getExtras() != null){
            if (getIntent().getExtras().containsKey("workout")){
                Log.d("RESUME", "resume has extra");
                setWorkout((Workout) getIntent().getSerializableExtra("workout"));
                whatShouldBeSaved = getIntent().getIntExtra("test", -1);
            }
        } else {
            Log.d("RESUME", "extras did not contain workout2");
        }

        Log.d("RESUME", "created? " + workout);
        Log.d("RESUME", "created? " + whatShouldBeSaved);
        }

        @Override
        public void onPause(){
        super.onPause();
        Log.d("ONPAUSE", "called");
        }


        @Override
        public void onStart(){
        super.onStart();
        Log.d("START", "starting act");
        }

        @Override
        public void onStop(){
        Log.d("STOP", "stopping act");
        super.onStop();
        }

        @Override
        public void onActivityResult(int requestCode, int resultCode, Intent intent) {
        super.onActivityResult(requestCode, resultCode, intent);
        Log.d("onACTRES", "called");
        }

        @Override
        public void onSaveInstanceState(Bundle savedInstanceState) {
        super.onSaveInstanceState(savedInstanceState);
        Log.d("SAVEINSTANCE", "called");
        savedInstanceState.putInt("test", whatShouldBeSaved);
        }

        @Override
        public void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);

        // Restore UI state from the savedInstanceState.
        // This bundle has also been passed to onCreate.
        Log.d("RESTOREINSTANCE", "called");

        whatShouldBeSaved = savedInstanceState.getInt("test", 1);
        Log.d("GOT SAVE", ""+ whatShouldBeSaved);
        }

        @Override
        public void onRestoreInstanceState(Bundle savedInstanceState, PersistableBundle persistentState){
        super.onRestoreInstanceState(savedInstanceState, persistentState);
        Log.d("RESTOREINSTANCE2", "called");
        }

        @Override
        public void onDestroy(){
        super.onDestroy();
        Log.d("DESTROY", "onDestroy called");
        Log.d("DESTROY", "destroying " + workout);
        Log.d("DESTROY", "destroying " + whatShouldBeSaved);
        Log.d("DESTROY", "was destroyed");
        //first = true;
        }
    }

下面是我的日志摘录

8151-8151/localhost.fitnessoptimizer D/STOP﹕ stopping act
01-10 13:26:45.110    8151-8151/localhost.fitnessoptimizer D/DESTROY﹕ onDestroy called
01-10 13:26:45.110    8151-8151/localhost.fitnessoptimizer D/DESTROY﹕ destroying Luffy
01-10 13:26:45.110    8151-8151/localhost.fitnessoptimizer D/DESTROY﹕ destroying -1
01-10 13:26:45.110    8151-8151/localhost.fitnessoptimizer D/DESTROY﹕ was destroyed
01-10 13:26:45.118    8151-8151/localhost.fitnessoptimizer D/onCreate﹕ called
01-10 13:26:45.118    8151-8151/localhost.fitnessoptimizer V/Monotype﹕ SetAppTypeFace- try to flip, app = localhost.fitnessoptimizer
01-10 13:26:45.118    8151-8151/localhost.fitnessoptimizer V/Monotype﹕ Typeface getFontPathFlipFont - systemFont = default#default
01-10 13:26:45.126    8151-8151/localhost.fitnessoptimizer W/ViewPager﹕ Requested offscreen page limit 0 too small; defaulting to 1
01-10 13:26:45.126    8151-8151/localhost.fitnessoptimizer D/CREATE﹕ created? null
01-10 13:26:45.126    8151-8151/localhost.fitnessoptimizer D/CREATE﹕ created? 1
01-10 13:26:45.127    8151-8151/localhost.fitnessoptimizer D/START﹕ starting act
01-10 13:26:45.129    8151-8151/localhost.fitnessoptimizer D/RESUME﹕ resuming act
01-10 13:26:45.129    8151-8151/localhost.fitnessoptimizer D/RESUME﹕ extras did not contain workout2
01-10 13:26:45.129    8151-8151/localhost.fitnessoptimizer D/RESUME﹕ created? null
01-10 13:26:45.129    8151-8151/localhost.fitnessoptimizer D/RESUME﹕ created? 1
01-10 13:26:45.152    8151-8151/localhost.fitnessoptimizer D/GOT WORKOUT﹕ null

onRestoreInstanceState从未被调用,而onCreate的savedInstanceState也不包含信息。如何保存或恢复锻炼(以及实际上只是调试变量whatShouldBeSaved)?

PS:我将我的代码放在snippet js标签中,因为它变得相当长。

2个回答

0

从官方网站 onSaveInstanceState

在活动被杀死之前调用以检索每个实例状态,以便可以在 onCreate(Bundle) 或 onRestoreInstanceState(Bundle) 中恢复状态(由此方法填充的 Bundle 将传递给两者)。

当您按下 BACK 键时,活动将关闭,但不会被杀死。当应用程序处于后台且系统需要暂时释放一些资源时,Android 系统可以执行“杀死”操作。

您需要使用 共享首选项 代替。


我已经尝试过这个方法,它确实有效。但是我认为这是一个可怕的解决方法,因为我必须将我的锻炼保存在一个JSON字符串中,然后重新加载并从JSON字符串中解析它,直接放置在那里之后。我真的不明白为什么活动会关闭,当它只是在那之后重新启动。为什么它不暂停和恢复呢? - infect
@infect请接受并投票答案,如果它有助于解决您当前的问题。 - gio
@infect请阅读下一篇文章http://developer.android.com/guide/components/activities.html#SavingActivityState,它将为您提供有关保存状态的更多详细信息。 - gio

0

onSaveInstanceState() 只有在您的活动意外销毁时才会被调用,而当活动当前被销毁时不会被调用。 onRestoreInstanceState() 也是如此。
官方网站,重新创建活动


你的链接说,savedInstanceState 在 onCreate 参数中,我在我的示例中尝试了这个方法,但它仍然不起作用!? - infect
@infect请仔细阅读所有文章,以了解它的工作原理,特别是注意事项块。 - gio

网页内容由stack overflow 提供, 点击上面的
可以查看英文原文,
原文链接