How does HashSet check two objects?

Question

class TestA extends Foo{
   private String a;
   private String b;
   private String c;

   public int hashcode() {
     // Use some inbuilt hashcode generator over a, b, c.
   }

   public boolean equals(Object a) {
     // a, b, c instance variables should match
   }
}

class TestB Extends Foo{
   private String a;
   private String b;
   private String c;

   public int hashcode() {
     // Same as Test A class implementation
   }

   public boolean equals(Object a) {
     // Same as Test A class implementation
   }
}

Say I add the following object into a HashSet:

TestA a = new TestA("a", "b", "c")

set.add(a);

Now, if I check the following object b is in the hashset, will set.contains(b) always return true?

TestB B = new TestB("a", "b", "c")

Answer 1

由于您的 HashSet 应该是HashSet<TestA>您甚至不应该能够将传递的 TestB 实例作为参数编译到contains 中。