Android 返回（onClickBack）到获取可序列化额外数据的活动

我已经尝试了各种各样的解决方案，似乎无法找到在不使用廉价黑客（如将数据保存到SharedReference等）的情况下实现此特定问题的最佳方法

我有一项活动需要来自intent extras的数据：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_problem_set);
    ButterKnife.bind(this);

    this.problemSet = (ProblemSet) getIntent().getSerializableExtra("problemSet");
    ...
}

当用户单击问题集中的特定问题时，我会生成一个新的活动，它只查看与问题集中特定问题相关联的数据。注意，这只是数据的一个视图（不需要为result启动活动，因为没有返回任何内容）

下面是从第一个创建活动开始，转到第二个创建活动，然后返回第二个创建活动的日志

03-30 13:23:50.021 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onCreate savedInstanceState=null
03-30 13:23:50.026 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onResume
03-30 13:23:54.324 2540-2540/io.gradem.gradem D/view_ps_activity: clicked on problem 
03-30 13:23:54.337 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onPause
03-30 13:23:54.354 2540-2540/io.gradem.gradem D/activity_feedback: ProblemFeedbackActivity.onCreate savedInstanceState=null
..... some over behavior before returning to previous activity ....
03-30 13:30:12.377 7266-7266/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onSaveInstanceState savedInstanceState=Bundle[{}]
03-30 13:23:58.861 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onCreate savedInstanceState=null

---

savedInstanceState实际上应该解决这个问题，但是使用单例类似乎更容易。

我继续实现了它，但仍然看到奇怪的行为。看我的编辑。使用一个单例类，它更容易。只是查了一下。。。太棒了。谢谢你的评论。事实上，这些额外的东西并没有被很明显地保留下来，这是某种设计缺陷。谢谢你的帮助。

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    Log.d(TAG, "ViewProblemSetActivity.onSaveInstanceState savedInstanceState=" + savedInstanceState);
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putSerializable("problemSet", problemSet);
}

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
    Log.d(TAG, "ViewProblemSetActivity.onRestoreInstanceState savedInstanceState=" + savedInstanceState);
    super.onRestoreInstanceState(savedInstanceState);
    this.problemSet = (ProblemSet)savedInstanceState.getSerializable("problemSet");
}

@Override
protected void onResume() {
    Log.d(TAG, "ViewProblemSetActivity.onResume");
    super.onResume();
}

@Override
protected void onPause() {
    Log.d(TAG, "ViewProblemSetActivity.onPause");
    super.onPause();
}

03-30 13:23:50.021 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onCreate savedInstanceState=null
03-30 13:23:50.026 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onResume
03-30 13:23:54.324 2540-2540/io.gradem.gradem D/view_ps_activity: clicked on problem 
03-30 13:23:54.337 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onPause
03-30 13:23:54.354 2540-2540/io.gradem.gradem D/activity_feedback: ProblemFeedbackActivity.onCreate savedInstanceState=null
..... some over behavior before returning to previous activity ....
03-30 13:30:12.377 7266-7266/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onSaveInstanceState savedInstanceState=Bundle[{}]
03-30 13:23:58.861 2540-2540/io.gradem.gradem D/view_ps_activity: ViewProblemSetActivity.onCreate savedInstanceState=null