Handle screen rotation without losing data - Android
android, android-intent, android-layout
Solution
can use override method `onSaveInstanceState()` and `onRestoreInstanceState()`. or to stop calling `onCreate()` on screen rotation just add this line in your manifest xml `android:configChanges="keyboardHidden|orientation"`
note: your custom class must implements `Parcelable` example below.
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelable("obj", myClass);
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onRestoreInstanceState(savedInstanceState);
myClass=savedInstanceState.getParcelable("obj"));
}
public class MyParcelable implements Parcelable {
private int mData;
public int describeContents() {
return 0;
}
/** save object in parcel */
public void writeToParcel(Parcel out, int flags) {
out.writeInt(mData);
}
public static final Parcelable.Creator<MyParcelable> CREATOR
= new Parcelable.Creator<MyParcelable>() {
public MyParcelable createFromParcel(Parcel in) {
return new MyParcelable(in);
}
public MyParcelable[] newArray(int size) {
return new MyParcelable[size];
}
};
/** recreate object from parcel */
private MyParcelable(Parcel in) {
mData = in.readInt();
}
}
Problem
I'm becoming crazy figuring out what is the best way to handle screen rotation. I read hundreds of questions/answers here but I'm really confused. How can I save myClass data before the activity is re-created so I can keep everything for redrawing activity without another useless initialization? Is there a cleaner and better way than parcelable? I need to handle rotation because I want to change layout in Landscape mode. ``` public class MtgoLifecounterActivity extends Activity { MyClass myClass; // Called when the activity is first created @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); If ( ?? first run...myClass == null ? ) { myClass = new MyClass(); } else { // do other stuff but I need myClass istance with all values. } // I want that this is called only first time. // then in case of rotation of screen, i want to restore the other instance of myClass which // is full of data. } ```