JAVA ArraySet<E> SET形式的有序LIST

Set形式的数组，数组内容重复

package com.sicdt.library.core.utils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
 * 
 * <br>类 名: ArraySet 
 * <br>描 述: 自定义Set
 * <br>作 者: shizhenwei 
 * <br>创 建: 2017年5月15日 
 * <br>版 本: v0.0.2 
 * <br>
 * <br>历 史: (版本) 作者 时间 注释
 */
public class ArraySet<E> implements Set<E> {

    private ArrayList<E> list;
    
    public ArraySet() {
        list = new ArrayList<>();
    }
    
    public ArraySet(int initialCapacity){
        list = new ArrayList<>(initialCapacity);
    }
    
    public ArraySet(Collection<? extends E> c) {
        list = new ArrayList<>(c);
    }
    
    @Override
    public int size() {
        return list.size();
    }

    @Override
    public boolean isEmpty() {
        return list.isEmpty();
    }

    @Override
    public boolean contains(Object o) {
        return list.contains(o);
    }

    @Override
    public Iterator<E> iterator() {
        return list.iterator();
    }

    @Override
    public Object[] toArray() {
        return list.toArray();
    }

    @Override
    public <T> T[] toArray(T[] a) {
        return list.toArray(a);
    }

    @Override
    public boolean add(E e) {
        if(list.contains(e)){
            return false;
        }
        return list.add(e);
    }

    @Override
    public boolean remove(Object o) {
        return list.remove(o);
    }

    @Override
    public boolean containsAll(Collection<?> c) {
        return list.containsAll(c);
    }

    @Override
    public boolean addAll(Collection<? extends E> c) {
        if(c == null || c.isEmpty()) return false;
        for(E e: c){
            add(e);
        }
        return true;
    }

    @Override
    public boolean retainAll(Collection<?> c) {
        return list.retainAll(c);
    }

    @Override
    public boolean removeAll(Collection<?> c) {
        return list.removeAll(c);
    }

    @Override
    public void clear() {
        list.clear();
    }
    
    @Override
    public String toString() {
        return list == null ? "[]" : list.toString();
    }

    public static void main(String[] args) {
        Set<String> set = new ArraySet<>();
        set.add("aa");
        set.add("cc");
        set.add("bb");
        set.add("cc");
        System.out.println(set);
        
        Map<String, String> map = new ArrayMap<>();
        map.put("a", "aa");
        map.put("b", "bb");
        map.put("c", "cc");
        map.put("a", "dd");
        System.out.println(map);
        
        System.out.println(map.keySet());
        
        Iterator<String> it = map.keySet().iterator();
        while(it.hasNext()){
            String key = it.next();
            String value = map.get(key);
            System.out.println(key + "," + value);
        }
    }
}