Created
February 23, 2017 23:01
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Save hrules6872/6b7d9e0889a96e58b3aacaf68d7e4cf3 to your computer and use it in GitHub Desktop.
Custom Viewgroup: onSaveInstanceState - onRestoreInstanceState http://trickyandroid.com/saving-android-view-state-correctly/
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public class CustomLayout extends LinearLayout { | |
@SuppressWarnings("unchecked") @Override public Parcelable onSaveInstanceState() { | |
Parcelable saveInstanceState = super.onSaveInstanceState(); | |
SavedState savedState = new SavedState(saveInstanceState); | |
savedState.childrenStates = new SparseArray(); | |
for (int i = 0; i < getChildCount(); i++) { | |
getChildAt(i).saveHierarchyState(savedState.childrenStates); | |
} | |
return savedState; | |
} | |
@SuppressWarnings("unchecked") @Override public void onRestoreInstanceState(Parcelable state) { | |
SavedState savedState = (SavedState) state; | |
super.onRestoreInstanceState(savedState.getSuperState()); | |
for (int i = 0; i < getChildCount(); i++) { | |
getChildAt(i).restoreHierarchyState(savedState.childrenStates); | |
} | |
} | |
@Override protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) { | |
dispatchFreezeSelfOnly(container); | |
} | |
@Override protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) { | |
dispatchThawSelfOnly(container); | |
} | |
private static class SavedState extends BaseSavedState { | |
private SparseArray childrenStates; | |
SavedState(Parcelable superState) { | |
super(superState); | |
} | |
private SavedState(Parcel in, ClassLoader classLoader) { | |
super(in); | |
childrenStates = in.readSparseArray(classLoader); | |
} | |
@SuppressWarnings("unchecked") @Override public void writeToParcel(Parcel out, int flags) { | |
super.writeToParcel(out, flags); | |
out.writeSparseArray(childrenStates); | |
} | |
public static final ClassLoaderCreator<SavedState> CREATOR = new ClassLoaderCreator<SavedState>() { | |
@Override public SavedState createFromParcel(Parcel source, ClassLoader loader) { | |
return new SavedState(source, loader); | |
} | |
@Override public SavedState createFromParcel(Parcel source) { | |
return createFromParcel(null); | |
} | |
public SavedState[] newArray(int size) { | |
return new SavedState[size]; | |
} | |
}; | |
} | |
} |
For those who use IcePick, you can use this. This does the same thing as above but lil less ceremony
import android.os.Parcel;
import android.os.Parcelable;
import android.util.SparseArray;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import icepick.State;
import static icepick.Icepick.restoreInstanceState;
import static icepick.Icepick.saveInstanceState;
class Util {
private Util() {}
public static SparseArray saveChildViewStates(ViewGroup viewGroup) {
SparseArray childViewStates = new SparseArray();
for (int i = 0; i < viewGroup.getChildCount(); i++) {
//noinspection unchecked
viewGroup.getChildAt(i).saveHierarchyState(childViewStates);
}
return childViewStates;
}
public static void restoreChildViewStates(ViewGroup viewGroup, SparseArray childViewStates) {
for (int i = 0; i < viewGroup.getChildCount(); i++) {
//noinspection unchecked
viewGroup.getChildAt(i).restoreHierarchyState(childViewStates);
}
}
}
public class CustomLayout extends LinearLayout {
@State
MyCustomParcellable myInternalState;
@State
int additionalState;
@State
SparseArray childViewStates;
@Override
public Parcelable onSaveInstanceState() {
childViewStates = Util.saveChildViewStates(this);
return saveInstanceState(this, super.onSaveInstanceState());
}
@Override
public void onRestoreInstanceState(Parcelable state) {
super.onRestoreInstanceState(restoreInstanceState(this, state));
Util.restoreChildViewStates(this, childViewStates);
childViewStates = null;
}
@Override protected void dispatchSaveInstanceState(SparseArray<Parcelable> container) {
dispatchFreezeSelfOnly(container);
}
@Override protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) {
dispatchThawSelfOnly(container);
}
}
class MyCustomParcellable implements Parcelable {
// lot of properties & parcellable implementation; use android studio extension (Android Parcelable Generator) to generate parcellable implementation
}
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Thanks, I saved my day. 👍