public class ClassA { int a; @Override public boolean equals(Object obj) { //реализация if (this == obj) return true; if (!obj instanceof(ClassA) return false; ClassA other = (ClassA) obj; return this.a == other.a; } } public class ClassB extends ClassA { int b; @Override public boolean equals(Object obj) { //реализация if (this == obj) return true; if (!obj instanceof(ClassB) return false; if (!super.equals(obj)) return false; ClassB other = (ClassB) obj; return this.b == other.b; } } ClassB b1 = new ClassB(a: 10, b: 20); ClassB b2 = new ClassB(a: 10, b: 20); assertTrue(b1.equals(b2));