Fragment save view state

Question

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>

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"));
}

So it solves saving the state of TextView.

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);
    }
}

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

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?

In your fragment class, how do you decide which ImageView to display and which one to hide? — Code-Apprentice, Jun 25 '18 at 11:13
You still need to provide more detail. What is "condition"? Do you really have a variable named `condition`? Or did you just replace your real code with that name? — Code-Apprentice, Jun 25 '18 at 11:16
Then all you need to do is store that boolean during `onSaveInstanceState()` and read it back during `onActivityCreated()`. Note that saving the text in your TextView is unnecessary since the call to `super.onSaveInstanceState()` should automagically take care of that for you. — Code-Apprentice, Jun 25 '18 at 11:19
@Code-Apprentice how can I do it, if I call `setIcon()` from some other class (so this boolean computes not inside Fragment class)? — Alex, Jun 25 '18 at 11:21
You should store `condition` as a private variable in your fragment. You should also rename this variable to something more descriptive. — Code-Apprentice, Jun 25 '18 at 11:24

Code-Apprentice · Accepted Answer · 2018-06-25T11:38:11.747

Inside your Fragment class, declare a private variable:

private boolean condition; // rename to something more descriptive

Now in setIcon() store the value:

this.condition = condition;

Finally save this to the bundle in onSaveInstanceState():

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

and read it in onActivityCreated():

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

Note

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

score 2 · Answer 2 · answered Jun 25 '18 at 11:33

You can either save the condition in outState like below:

outState.putBoolean("condition", condition);

and then read it and update the image views

setIcon(savedInstanceState.getBoolean("condition"))

Or You can save the visibility state of the image views by putInt method:

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

and then restore the state:

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

I didn't know, I can save visibility status. Saving boolean seems like a better option though, thank you. — Alex, Jun 25 '18 at 11:40

Fragment save view state

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