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What are the Methods of Collection interface in Java?

There are many methods declared in the Collection interface. They are as follows:
boolean add (Object o)
Ensures that this collection contains the specified element (optional operation).

boolean addAll(Collection c)
Adds all of the elements in the specified collection to this collection (optional operation).

void clear()
Removes all of the elements from this collection (optional operation).

boolean contains(Object o)

Returns true if this collection contains the specified element.

boolean containsAll(Collection c)
Returns true if this collection contains all of the elements in the specified collection.

boolean equals(Object o)
Compares the specified object with this collection for equality.

int hashCode()
Returns the hash code value for this collection.

boolean isEmpty()
Returns true if this collection contains no elements.

Iterator iterator()
Returns an iterator over the elements in this collection.

boolean remove(Object o)
Removes a single instance of the specified element from this collection, if it is present (optional operation).

boolean removeAll(Collection c)
Removes all this collection's elements that are also contained in the specified collection (optional operation).

boolean retainAll(Collection c)
Retains only the elements in this collection that are contained in the specified collection (optional operation).

int size()
Returns the number of elements in this collection.

Object[] toArray()
Returns an array containing all of the elements in this collection.

Object[] toArray(Object[] a)
Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.

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