我想为屏幕方向更改(纵向/横向)保存和恢复一些数据。
为此,我在我的类中实现了 onSaveInstanceState 和 onRestoreInstanceState ,其中包含我要恢复的列表。它似乎正在工作,并且在 MyObject 类中我实现了Parcelable。
问题是我的对象扩展了 GifImageButton并实现了Parcelable,所以我在对象构造函数中收到此错误:“pl.droidsonroids.gif.GifImageButton 没有可用的默认构造函数”
public class MyDerivedClass extends MyBaseClass { // extends AppCompatActivity
ArrayList<MyObject> list;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.episode_five);
if(savedInstanceState == null || !savedInstanceState.containsKey("key")) {
String[] colors = {"black", "red"};
String[] numbers = {"one", "two"};
list = new ArrayList<MyObject>();
for(int i = 0; i < numbers.length; i++)
list.add(new MyObject(numbers[i], colors[i]));
}
else {
list = savedInstanceState.getParcelableArrayList("key");
}
}
@Override
protected void onSaveInstanceState(Bundle outState) {
outState.putParcelableArrayList("key", list);
super.onSaveInstanceState(outState);
}
@Override
protected void onRestoreInstanceState(Bundle inState) {
list = inState.getParcelableArrayList("key");
super.onSaveInstanceState(inState);
init();
}
public void init() {
list.add(new MyObject("three", "transparent"));
list.add(new MyObject("for", "white"));
}
}
对于问题,请查看以下代码:
我想扩展 GifImageButton但随后出现错误“pl.droidsonroids.gif.GifImageButton 没有可用的默认构造函数”:
public MyObject(String number, String color) AND public MyObject(Parcel in)
注意:如果我删除:“extends GifImageButton”和“public MyObject(Context context, AttributeSet attrs)”,则编译代码。
class MyObject extends GifImageButton implements Parcelable {
String color;
String number;
public MyObject(Context context, AttributeSet attrs) {
super(context, attrs);
setImageResource(R.drawable.a);
}
public MyObject(String number, String color) {
this.color = color;
this.number = number;
}
private MyObject(Parcel in) {
color = in.readString();
number = in.readString();
}
public int describeContents() {
return 0;
}
@Override
public String toString() {
return number + ": " + color;
}
public void writeToParcel(Parcel out, int flags) {
out.writeString(color);
out.writeString(number);
}
public static final Parcelable.Creator<MyObject> CREATOR = new Parcelable.Creator<MyObject>() {
public MyObject createFromParcel(Parcel in) {
return new MyObject(in);
}
public MyObject[] newArray(int size) {
return new MyObject[size];
}
};
}
我可以在实现 Parcelable 的对象类中扩展 GifImageButton 吗?如果没有,那么我该如何解决?