Simple sample of overrided equals and hashcode methods in java

Equals_HashCode.java

    @Override
    public boolean equals(@Nullable Object o) {
        if (o == null) {
            return false;
        }

        if (o == this) {
            return true;
        }

        if (!(o instanceof MyObject)) {
            return false;
        }

        MyObject other = (MyObject) o;
        return url != null && url.equals(other.url)
                && size == other.size;
    }

    @Override
    public int hashCode() {
        int hash = 7;
        hash = 31 * hash + size;
        hash = 31 * hash + (url == null ? 0 : url.hashCode());
        return hash;
    }