Java: 集合类

Set

public interface Set<E> extends Collection<E>
{
    //基本操作
    int size();
    boolean isEmpty();
    boolean contains(Objects element);
    boolean add(E element);
    boolean remove(Objects element);
    Iterator<E> iterator();
    boolean containsAll(Collection <?> c);
    boolean addAll(Collection<?extends E> c);//将集合c的元素添加到本集合
    boolean removeAll(Collection<?> c);
    boolean retainAll(Collection<?> c);//只保留属于c的元素
    void clear();
    Objects[] toArray();
    <T>T[] toArray(T[] a);
}

JDK 提供 Set 接口 3 个实用类

• HashSet，采用 Hash, 无固定顺序

• TreeSet，实现 SortedSet 接口，有序

• LinkedHashSet，有固定顺序

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List

public interface List<E> extends Collection<E>{
    E get(int index);
    E set(int index,E element);
    boolean add(E element);
    void add(int index,E element);
    E remove(int index);
    boolean addAll(int index,Collection<? extends E> c);
    //查找
    int indexOf(Object o);
    int lastIndexOf(Object o);
    ListIterator<E> listIterator();
    ListIterator<E> listIterator(int index);
    Lis<E> subList(int from,int to);
}

JDK 提供 Set 接口 3 个实用类

• ArrayList, 效率最高

• LinkedList, 还提供在结尾和开头 get,remove,insert

• Vector

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Queue

public interface Queue<E> extends Collection<E> {
    E element();
    boolean add(E e);
    boolean offer(E e);
    E remove();
    E poll();
    E peek();
}

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Map

public interface Map<K, V> {
    int size();
    V put(K key,V value);
    V get(Object key);
    V remove(Object key);
    boolean containsKey(Object key);
    boolean containsValue(Object value);
    int size();
    boolean isEmpty();
    void putAll(Map<?extends K,?extends V>m);
    void clear();
    public Set(K) keySet();
    public Collection<V> values();
    public Set<Map.Entry<k,v>> entrySet();
    public interface Entry{
        K getKey();
        V getValue();
        V setValue(V value);
    }
}

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