片段必须是公共静态类，才能从实例状态正确地重新创建 [英] Fragment must be a public static class to be properly recreated from instance state

问题描述

更新到最新的支持存储库后，

After updating to the latest support repository,

compile 'com.android.support:appcompat-v7:24.2.0'
compile 'com.android.support:design:24.2.0'
compile 'com.android.support:percent:24.2.0'
compile 'com.android.support:recyclerview-v7:24.2.0'

我遇到了奇怪的异常.

java.lang.IllegalStateException: Fragment null must be a public static class to be  properly recreated from instance state.
at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:435)
at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:414)
at android.support.v4.app.DialogFragment.show(DialogFragment.java:154)
at com.androidapp.base.BaseActivity.showDialogFragment(BaseActivity.java:78)
at com.androidapp.MainActivity.showNewDialog(MainActivity.java:304)
at com.androidapp.MainActivity$6.onClick(MainActivity.java:228)

在我的 BaseActivity 类中，我创建了一个可重用的片段，该片段可用于扩展 BaseActivty

In my BaseActivity class, I've created a re-usable fragment which can be used in activity class that extends the BaseActivty

public void showDialogFragment(DialogFragment newFragment) {
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        Fragment prev = getSupportFragmentManager().findFragmentByTag("dialog");
        if (prev != null) {
            ft.remove(prev);
        }
        ft.addToBackStack("dialog");
        newFragment.show(ft, "dialog");
    }

回到 MainActivty ，我使用了这样的片段，

Back to the MainActivty I've used the fragment like this,

public class MainActivity extends BaseActivity {

    @SuppressLint("ValidFragment")
        public void showNewDialog(int type, String title, String message) {
            final DialogNew dialog = new DialogNew() {
                @Override
                public void success(boolean isLandscape) {
                    .......
                }

                @Override
                public void cancel() {

                }
            };
            dialog.setArgs(title, message);
            super.showDialogFragment(dialog);
        }
}

DialogNew 类在下面，

public abstract class DialogNew extends DialogFragment {

    private View rootView;

    private String title;
    private String message;

    public void setArgs(String title, String message) {
        Bundle args = new Bundle();
        args.putString("title", title);
        args.putString("message", message);
        setArguments(args);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setStyle(STYLE_NO_TITLE, 0);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        rootView = inflater.inflate(R.layout.fragment_new_dialog, container, false);

        init();
        setListeners();

        return rootView;
    }

    public abstract void success(boolean isLandscape);

    public abstract void cancel();
}

PS:相同的代码可用于较早的支持存储库.

PS: The same code works with older support repository.

推荐答案

该错误不是特别奇怪.如果您之前没有收到此错误，则那个很奇怪.

The error is not especially weird. If you were not getting this error before, that was weird.

Android会销毁并重新创建片段，这是配置更改的一部分(例如，屏幕旋转)，以及在需要时重建任务的一部分(例如，用户切换到另一个应用程序，您的应用程序在后台运行时会终止，然后用户尝试在30分钟左右的时间内全部返回您的应用). Android无法重新创建DialogNew的匿名子类.

Android destroys and recreates fragments as part of a configuration change (e.g., screen rotation) and as part of rebuilding a task if needed (e.g., user switches to another app, your app's process is terminated while it is in the background, then the user tries to return to your app, all within 30 minutes or so). Android has no means of recreating an anonymous subclass of DialogNew.

因此，建立一个常规的public Java类(或一个public static嵌套类)，该类扩展了DialogNew并具有您的业务逻辑，替换了您当前使用的DialogNew的匿名子类.

So, make a regular public Java class (or a public static nested class) that extends DialogNew and has your business logic, replacing the anonymous subclass of DialogNew that you are using presently.

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