public class SumClass implements Serializable {
    private Date someDate;
    private String a;
    private String b;
    private String c;

    @Override
    public boolean equals(Object obj) {

        if (obj == null) {
            return false;
        }

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

        if (!(obj instanceof SumClass)) {
            return false;
        }

        SumClass sdk = (SumClass) obj;
        return someDate.equals(sdk.someDate) && a.equals(sdk.a) && b.equals(sdk.b) && c.equals(sdk.c);

    }

    @Override
    public int hashCode() {
        int result = someDate != null ? someDate.hashCode() : 0;
        result = 31 * result + ( a != null ? a.hashCode() : 0 );
        result = 31 * result + ( b != null ? b.hashCode() : 0 );
        result = 31 * result + ( c != null ? c.hashCode() : 0 );
        return result;
    }

}