java - setRetainInstance 不保留实例

Question

我正在尝试使用 setRetainInstance()，但它似乎对我不起作用! =(。我将问题简化为最简单的版本:

我有一个带有 TextView 和 Button 的 fragment 。

TextView 的初始文本是“I'm waiting”，当按下按钮时文本变为“Hello!”

这是我的代码:

fragment :

public class SayHelloFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.say_hello_layout, container);
        final TextView text = (TextView) view.findViewById(R.id.textView1);
        view.findViewById(R.id.button1).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                text.setText("Hello!");

            }
        });
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        setRetainInstance(true);
    }

}

Activity :

public class MainActivity extends FragmentActivity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

}

Activity 的布局:

<?xml version="1.0" encoding="utf-8"?>
<fragment xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/say_hello_fragment"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    class="com.example.retaintext.SayHelloFragment" />

fragment 的布局:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >


    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="I&apos;m Waiting"
        android:textAppearance="?android:attr/textAppearanceLarge" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Button" />

</LinearLayout>

但是当我播放它时，按下按钮并更改设备的方向，文本会重置。

我错过了什么？我该如何解决？谢谢!

Answer 1

您错过了 onCreateView 在旋转后再次运行并再次使用默认文本扩充默认 View 。

您需要手动恢复 View 的状态，例如:

public class SayHelloFragment extends Fragment {

    private String mText;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.say_hello_layout, container);
        final TextView text = (TextView) view.findViewById(R.id.textView1);
        if (mText != null)
            text.setText(mText);

        view.findViewById(R.id.button1).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                mText = "Hello!";
                text.setText(mText);
            }
        });
        return view;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        setRetainInstance(true);
    }

}