Android自定义复合视图保存和恢复状态不起作用

解决了…

我有一个包含一些其他控件的复合视图.我试图覆盖保存onSaveInstanceState和onRestoreInstanceState,但我得到一个奇怪的结果.

onRestoreInstanceState的Parcelable状态参数不是我的自定义子类BaseSavedState,SavedState,并且似乎总是BaseSavedState.EMPTY_STATE. (在下面查找“总是失败”的代码注释…

似乎问题可能在于保存部分,因为在onSaveInstanceState进入后没有调用SavedState.writeToParcel.几乎就像调用onSaveInstanceState的人在将结果保持到Parcel之前抛出结果一样.

如果它有所不同,则此视图托管在片段中.

有任何想法吗？

这是我的班级定义：

public class AddressInput extends FrameLayout

这是我的onSaveInstanceState和onRestoreInstanceState对：

@Override
protected Parcelable onSaveInstanceState()
{
    // Return saved state
    Parcelable superState = super.onSaveInstanceState();
    return new AddressInput.SavedState( superState, mCurrentLookUp );
}

@Override
protected void onRestoreInstanceState( Parcelable state )
{
    // **** (state == BaseSavedState.EMPTY_STATE) is also always true 

    // Cast state to saved state
    if ( state instance of AddressInput.SavedState )     // **** <---  always fails
    {
        AddressInput.SavedState restoreState = (AddressInput.SavedState)state;

        // Call super with its portion
        super.onRestoreInstanceState( restoreState.getSuperState() );

        // Get current lookup
        mCurrentLookUp = restoreState.getCurrentLookup();
    }
    else
        // Just send to super
        super.onRestoreInstanceState( state );
}

这是我的自定义BaseSavedState子类(AddressInput的内部类)：

public static class SavedState extends BaseSavedState
{
    private String mCurrentLookup;

    public SavedState(Parcelable superState, String currentLookup)
    {
        super(superState);
        mCurrentLookup = currentLookup;
    }

    private SavedState(Parcel in)
    {
        super(in);
        this.mCurrentLookup = in.readString();
    }

    public String getCurrentLookup()
    {
        return mCurrentLookup;
    }

    @Override
    public void writeToParcel(Parcel out, int flags)
    {
        super.writeToParcel(out, flags);
        out.writeString( this.mCurrentLookup );
    }

    public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>()
    {
        public AddressInput.SavedState createFromParcel(Parcel in)
        {
            return new AddressInput.SavedState(in);
        }

        public AddressInput.SavedState[] newArray(int size) {
            return new AddressInput.SavedState[size];
        }
    };
}

解决方法:

想出来……我的自定义视图与其自定义视图的特定实例使用的FrameLayout具有相同的ID.实例正确保存状态,然后由没有状态持久的FrameLayout覆盖(清除).

我还将其基类更改为更有意义的RelativeView.

在自定义视图的XML中：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:id="@+id/addressInput"
            android:background="@drawable/rounded_edit">

和实例用法：

    <com.myStuff.AddressInput
            android:layout_height="wrap_content"
            android:layout_width="fill_parent"
            android:id="@+id/addressInput"
            android:layout_marginTop="10dp"
            app:addressMode="Domestic"
            app:showSelect="true"
            app:showClear="true" />

更改为：(@ id / addressInput – > @ id / shippingAddress)

    <com.myStuff.AddressInput
            android:layout_height="wrap_content"
            android:layout_width="fill_parent"
            android:id="@+id/shippingAddress"
            android:layout_marginTop="10dp"
            app:addressMode="Domestic"
            app:showSelect="true"
            app:showClear="true" />

让你希望有一些范围确定ID来防止这种事情.为什么您必须了解自定义视图的内部结构以确保避免ID冲突？

标签：android,custom-view,state,android-custom-view,onrestoreinstancestate
来源： https://codeday.me/bug/20190725/1532231.html