当我尝试编译时，我收到了一个关于makeUnion方法的错误消息，我猜我也会得到一个makeIntersection。如果我想为新集添加一个set接口，我不知道为什么会这样，或者如何实现makeUnion。有人可以向我解释我做错了什么吗？
public class Set<T> implements SetInterface<T>
{
private HashSet<T> set;
/**
* Constructs a new empty set.
*/
public Set () {
set = new HashSet <>();
}
/**
* Constructs a new set containing the elements in the specified collection.
* Default load factor of 0.75 and initial capacity of 50.
*
* @param c- the collection whose elements are to be place into this set
*/
public Set(Collection <? extends T> c) {
set = new HashSet<>(Math.max((int) (c.size()/.75f) + 1, 50));
set.addAll(c);
}
/**
* Constructs a new empty set. Default load factor of 0.75.
*
* @param initialCapacity- the initial capacity of the hash table
*/
public Set(int initialCapacity) {
set = new HashSet <>(initialCapacity);
}
/**
* Constructs a new empty set.
* Hashmap has specified initial capacity and specified load factor.
*
* @param initialCapacity- the initial capacity of the hash table
* loadFactor- the load factor of the hash map
*/
public Set(int initialCapacity, float loadFactor) {
set = new HashSet <>(initialCapacity, loadFactor);
}
/**
* Add an item of type T to the interface Duplicate items will not be
* added to the set.
*
* @param itemToAdd - what to add.
*/
public void add(T itemToAdd) {
set.add(itemToAdd);
}
/**
* Removes an item from the set ( if the item is in the set) If the item is not
* in the set this operation does nothing
*
* @param item to remove.
*/
public void remove( T itemToDelete) {
set.remove(itemToDelete);
}
/**
* Return if the SetInterface contains an item
*
* @param itemToCheck. The item you are looking for
* @return true if found. False if not found.
*/
public boolean contains( T itemToCheck) {
return set.contains(itemToCheck);
}
/**
* Make a union of two sets. We add all items in either set to a new set and
* return the new set.
*
* @param the 'other' set to add to our set.
* @return A new set which is the union of the two sets.
*/
public Set<T> makeUnion( SetInterface<T> otherSet) {
return set.addAll(otherSet);
}
/**
* Make an intersection of two sets. We add create a new set which only has
* items in it that are contained in both sets.
*
* @param the 'other' set to intersect with
* @return A new set which is the intersection of the two sets.
*/
public Set<T> makeIntersection( SetInterface<T> otherSet) {
return set.retainAll(otherSet);
}
/**
* Return an iterator for the set. This is used to walk thought all elements
* in the set
*
* @return The iterator
*/
public Iterator<T> getIterator() {
return set.iterator();
}
/**
* Tell the caller how many elements are in the set
*
* @return int with the number of elements
*/
public int size() {
return set.size();
}
}
答案 0 :(得分：-1)
interface SetInterface<T> {
void add(T itemToAdd);
public void remove( T itemToDelete);
public boolean contains( T itemToCheck);
public Set<T> makeUnion( SetInterface<T> otherSet);
public Iterator<T> getIterator();
public int size();
HashSet<T> getSet();
}
public class Set<T> implements SetInterface<T>
{
private HashSet<T> set;
public HashSet<T> getSet() {
return set;
}
/**
* Constructs a new empty set.
*/
public Set () {
set = new HashSet <>();
}
/**
* Constructs a new set containing the elements in the specified collection.
* Default load factor of 0.75 and initial capacity of 50.
*
* @param c- the collection whose elements are to be place into this set
*/
public Set(Collection <? extends T> c) {
set = new HashSet<>(Math.max((int) (c.size()/.75f) + 1, 50));
set.addAll(c);
}
/**
* Constructs a new empty set. Default load factor of 0.75.
*
* @param initialCapacity- the initial capacity of the hash table
*/
public Set(int initialCapacity) {
set = new HashSet <>(initialCapacity);
}
/**
* Constructs a new empty set.
* Hashmap has specified initial capacity and specified load factor.
*
* @param initialCapacity- the initial capacity of the hash table
* loadFactor- the load factor of the hash map
*/
public Set(int initialCapacity, float loadFactor) {
set = new HashSet <>(initialCapacity, loadFactor);
}
/**
* Add an item of type T to the interface Duplicate items will not be
* added to the set.
*
* @param itemToAdd - what to add.
*/
public void add(T itemToAdd) {
set.add(itemToAdd);
}
/**
* Removes an item from the set ( if the item is in the set) If the item is not
* in the set this operation does nothing
*
* @param item to remove.
*/
public void remove( T itemToDelete) {
set.remove(itemToDelete);
}
/**
* Return if the SetInterface contains an item
*
* @param itemToCheck. The item you are looking for
* @return true if found. False if not found.
*/
public boolean contains( T itemToCheck) {
return set.contains(itemToCheck);
}
/**
* Make a union of two sets. We add all items in either set to a new set and
* return the new set.
*
* @param the 'other' set to add to our set.
* @return A new set which is the union of the two sets.
*/
public Set<T> makeUnion( SetInterface<T> otherSet) {
set.addAll(new java.util.ArrayList<T>(otherSet.getSet()));
return this;
}
/**
* Return an iterator for the set. This is used to walk thought all elements
* in the set
*
* @return The iterator
*/
public Iterator<T> getIterator() {
return set.iterator();
}
/**
* Tell the caller how many elements are in the set
*
* @return int with the number of elements
*/
public int size() {
return set.size();
}
}