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package com.google.gson.internal;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.RandomAccess;
/**
* {@link List} which wraps another {@code List} but prevents insertion of
* {@code null} elements. Methods which only perform checks with the element
* argument (e.g. {@link #contains(Object)}) do not throw exceptions for
* {@code null} arguments.
*/
public class NonNullElementWrapperList<E> extends AbstractList<E> implements RandomAccess {
// Explicitly specify ArrayList as type to guarantee that delegate implements RandomAccess
private final ArrayList<E> delegate;
public NonNullElementWrapperList(ArrayList<E> delegate) {
this.delegate = Objects.requireNonNull(delegate);
}
@Override public E get(int index) {
return delegate.get(index);
}
@Override public int size() {
return delegate.size();
}
private E nonNull(E element) {
if (element == null) {
throw new NullPointerException("Element must be non-null");
}
return element;
}
@Override public E set(int index, E element) {
return delegate.set(index, nonNull(element));
}
@Override public void add(int index, E element) {
delegate.add(index, nonNull(element));
}
@Override public E remove(int index) {
return delegate.remove(index);
}
/* The following methods are overridden because their default implementation is inefficient */
@Override public void clear() {
delegate.clear();
}
@Override public boolean remove(Object o) {
return delegate.remove(o);
}
@Override public boolean removeAll(Collection<?> c) {
return delegate.removeAll(c);
}
@Override public boolean retainAll(Collection<?> c) {
return delegate.retainAll(c);
}
@Override public boolean contains(Object o) {
return delegate.contains(o);
}
@Override public int indexOf(Object o) {
return delegate.indexOf(o);
}
@Override public int lastIndexOf(Object o) {
return delegate.lastIndexOf(o);
}
@Override public Object[] toArray() {
return delegate.toArray();
}
@Override public <T> T[] toArray(T[] a) {
return delegate.toArray(a);
}
@Override public boolean equals(Object o) {
return delegate.equals(o);
}
@Override public int hashCode() {
return delegate.hashCode();
}
// TODO: Once Gson targets Java 8 also override List.sort
}
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