android - 如何在不实现 parcelable 的情况下保存自定义对象 onSaveInstanceState

Question

我需要保存一个我在 fragment 中使用的自定义对象，这样它就不会在屏幕旋转时丢失(当应用程序调用 onDestroy 然后调用 onCreate 时)

现在通常的做法是实现 Parcelable 接口(interface)并将其作为 Parcelable 对象保存到包中。

这是一种非常乏味的做事方式。

有没有办法将对象作为“putObject”方法传递？

Answer 1

您可以将数据保存在 fragment 中，在配置更改期间保留，如 example .

Extend the Fragment class and declare references to your stateful objects.

public class RetainedFragment extends Fragment {
    // data object we want to retain
    private MyDataObject data;
    // this method is only called once for this fragment
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // retain this fragment
        setRetainInstance(true);
    }
    .. getter and setter
}

Then use FragmentManager to add the fragment to the activity.

public class MyActivity extends Activity {

    private RetainedFragment dataFragment;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        ..    
        // find the retained fragment on activity restarts
        FragmentManager fm = getFragmentManager();
        dataFragment = (RetainedFragment) fm.findFragmentByTag(“data”);

        // create the fragment and data the first time
        if (dataFragment == null) {
            // add the fragment
            dataFragment = new DataFragment();
            fm.beginTransaction().add(dataFragment, “data”).commit();
        } else { 
            // available dataFragment.getData()
            .. 
           // save data in onDestroy dataFragment.setData(yourData);