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package cgeo.geocaching.utils;
import org.eclipse.jdt.annotation.NonNull;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Callable;
public abstract class LazyInitializedList<ElementType> extends AbstractList<ElementType> implements Callable<List<ElementType>> {
private volatile List<ElementType> list;
@NonNull
public List<ElementType> getUnderlyingList() {
if (list == null) {
synchronized(this) {
try {
list = call();
if (list == null) {
Log.e("LazyInitializedList.getList: null result");
}
} catch (final Exception e) {
Log.e("LazyInitializedList.getList", e);
}
if (list == null) {
Log.e("LazyInitializedList.getList: using an empty list as a fallback");
list = Collections.emptyList();
}
}
}
return list;
}
@Override
public boolean add(final ElementType element) {
return getUnderlyingList().add(element);
}
@Override
public ElementType set(final int index, final ElementType element) {
return getUnderlyingList().set(index, element);
}
@Override
public ElementType remove(final int index) {
return getUnderlyingList().remove(index);
}
@Override
public void add(int index, final ElementType element) {
getUnderlyingList().add(index, element);
}
@Override
public int size() {
return getUnderlyingList().size();
}
@Override
public ElementType get(final int index) {
return getUnderlyingList().get(index);
}
@Override
public void clear() {
list = new ArrayList<>();
}
}
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