judgement method of collections

When the collections want to evaluate the object is different from another object or not,it first to judge the mothod of hashcode() and equals()

		Set set = new HashSet();
		Integer a = new Integer(10);
		Integer b = new Integer(10);
		
		set.add(a);
		set.add(b);
		System.out.println(a==b);
		System.out.println(a.hashCode());
		System.out.println(a.hashCode()==b.hashCode());
		System.out.println(a.equals(b));
		System.out.println(set.size());

 

result is :

    false
    10
    true
    true
    1