我很快就创建了这个自定义集合，它的行为就像一个ArrayList，但是它不允许重复，你可能需要修改它来满足你的需要。

class UniqueArrayList<E> extends ArrayList<E> {

private static final long serialVersionUID = 1357048473879966517L;

public UniqueArrayList(int initialCapacity){
    super(initialCapacity);
}

public UniqueArrayList(){
    super();
}

// sets the given index to the given value 
// if the list doesn't contain an equivalent value
@Override
public E set(int index,E e){
    if(!contains(e)) {
    return super.set(index,e);
    }
    if(indexOf(e)==index) {
        return e;
    }
    throw new IllegalArgumentException("Cannot set a value already in the list");
}

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

@Override
public void add(int index,E e){
    if(!contains(e)) {
    super.add(index,e);
    }
}

@Override
public boolean addAll(Collection<? extends E> c){
    boolean someAdded = false;
    for(E item : c) {
        if(!contains(item)) {
            super.add(item);
            someAdded = true;
        }
    }
    return someAdded;
}

@Override
public boolean addAll(int index,Collection<? extends E> c){
    boolean someAdded = false;
    for(E item : c) {
        if(!contains(item)) {
            super.add(index,item);
            index++;
            someAdded = true;
        }
    }
    return someAdded;
  }
 }