Can two objects of different classes be considered equal if all their fields and values match?

In Java, objects of different classes cannot be considered equal, even if they have identical fields and values. The equals() method by default compares references, and when overridden, it usually considers the class of the object.

Reasons:

• Objects of different classes may have the same fields but different meanings and behaviors.
• Violation of the symmetry principle: if a.equals(b) returns true, then b.equals(a) should also return true. With different classes, this is difficult to guarantee.

If it is absolutely necessary to compare objects of different classes by content, such logic should be explicitly implemented in the equals() method, but this is not standard practice and can lead to errors.

A standard approach example:

@Override
public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null || getClass() != obj.getClass()) return false;
    MyClass other = (MyClass) obj;
    return Objects.equals(field1, other.field1) && Objects.equals(field2, other.field2);
}

Here, only objects of the same class are compared.