Collection旗下抽象类AbstractCollection

public abstract class AbstractCollection<E> implements Collection<E>

我们来看AbstractCollection为Collection接口中的哪些方法提供了实现

public boolean isEmpty(){}
public boolean contains(Object o){}
public Object[] toArray(){}
public <T> T[] toArray(T[] a){}
public boolean add(E e){//抛出异常}
public boolean remove(Object o){}
public boolean containsAll(Collection<?> c){}
public boolean addAll(Collection<? extends E> c){}
public boolean removeAll(Collection<?> c){}
public boolean retainAll(Collection<?> c){}
public void clear(){}

//新增方法
public String toString(){}