片段保存视图状态 [英] Fragment save view state

问题描述

我有一些具有这种结构的片段:

I have some Fragment with this structure:

    <RelativeLayout
        android:id="@+id/control_panel"
        android:visibility="gone">

        <RelativeLayout
            android:id="@+id/control_panel_icon">

            <ImageView
                android:id="@+id/control_panel_icon_1"
                android:src="@drawable/ic_control_panel_icon_1" />

            <ImageView
                android:id="@+id/control_panel_icon_2"
                android:src="@drawable/ic_control_panel_icon_2"
                android:visibility="gone"/>
        </RelativeLayout>

        <TextView
            android:id="@+id/control_panel_tv"
            android:text="@string/not_available" />
    </RelativeLayout>

在Fragment类中，我有 onSaveInstanceState 和 onActivityCreated :

And inside Fragment class i have onSaveInstanceState and onActivityCreated:

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putString("tv", panel_tv.getText().toString());
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    if (savedInstanceState != null) 
        panel_tv.setText(savedInstanceState.getString("tv"));
}

因此它解决了保存 TextView 的状态的问题.

So it solves saving the state of TextView.

在Fragment类中，我还设置了要显示某些功能的图像:

Inside Fragment class I also setup which image to display with some function:

public void setIcon(boolean condition){
    if (condition) {
         control_panel_icon_1.setVisibility(View.GONE);
         control_panel_icon_2.setVisibility(View.VISIBLE);
    } else {
         control_panel_icon_1.setVisibility(View.VISIBLE);
         control_panel_icon_2.setVisibility(View.GONE);
    }
}

有什么方法可以保存和恢复当前显示的图像?

Is there any way to save and restore which image is currently displayed?

我知道，我不应该保存整个小部件，但是如果我可以保存 RelativeLayout 的状态，它将恢复所有子状态吗?

I know, what I'm shouldn't save entire widgets, but if I can save state of RelativeLayout will it restore all it's child's states?

推荐答案

在Fragment类中，声明一个私有变量:

Inside your Fragment class, declare a private variable:

private boolean condition; // rename to something more descriptive

现在在 setIcon()中存储值:

this.condition = condition;

最后将其保存到 onSaveInstanceState()中的捆绑软件中:

Finally save this to the bundle in onSaveInstanceState():

outState.putBoolean("condition", this.condition);

并在 onActivityCreated()中读取它:

this.condition = savedInstanceState.getBoolean("condition");
this.setIcon(this.condition);

注意

您无需保存 TextView 中的文本.对 super.onSaveInstanceState()的调用已经为您完成了此工作.

You don't need to save the text from your TextView. The call to super.onSaveInstanceState() already takes care of this for you.

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