片段保存视图状态

Question

我有一些具有这种结构的片段：

    <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>

在片段 class 里面我有 onSaveInstanceState 和 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"));
}

所以它解决了保存TextView的状态。

Inside Fragment class 我还设置了使用某些功能显示的图像：

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片吗？

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，它会恢复所有子项的状态吗？

Answer 1

在您的片段中 class，声明一个私有变量：

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() 中的包中：

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

并在onActivityCreated()阅读：

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

备注

您不需要保存 TextView 中的文本。调用 super.onSaveInstanceState() 已经为您解决了这个问题。

Answer 2

您可以将 condition 保存在 outState 中，如下所示：

outState.putBoolean("condition", condition);

然后阅读并更新图片浏览量

setIcon(savedInstanceState.getBoolean("condition"))

或者您可以通过putInt方法保存图像视图的可见状态：

outState.putInt("ic1", control_panel_icon_1.getVisibility());
outState.putInt("ic2", control_panel_icon_2.getVisibility());

然后恢复状态：

control_panel_icon_1.setVisibility(savedInstanceState.getInt("ic1"));
control_panel_icon_2.setVisibility(savedInstanceState.getInt("ic2"));

片段保存视图状态

Fragment save view state

android

android-layout

android-fragments

onsaveinstancestate