1 package de.dlr.shepard.util;
2
3 import com.fasterxml.jackson.annotation.JsonIgnore;
4 import java.util.List;
5
6 @FunctionalInterface
7 public interface HasId {
8 /**
9 * Returns a specific unique identifier for this object
10 *
11 * @return String of the unique identifier
12 */
13 @JsonIgnore
14 String getUniqueId();
15
16 /**
17 * This function compares two lists of objects. These lists are equal if both
18 * are sorted in the same way and each object is equal when compared by its
19 * unique ID. Other attributes are ignored.
20 *
21 * @param a The first list
22 * @param b The second list
23 * @return True of both lists are equal
24 */
25 static boolean equalsHelper(List<? extends HasId> a, List<? extends HasId> b) {
26 if (a == null && b == null) return true;
27 if (a == null || b == null) return false;
28 if (a.size() != b.size()) return false;
29 // TODO: Should we sort these lists?
30 for (int i = 0; i < a.size(); i++) {
31 if (!equalsHelper(a.get(i), b.get(i))) return false;
32 }
33 return true;
34 }
35
36 /**
37 * This function compares two objects. These objects are equal if their unique
38 * ID is equal. Other attributes are ignored.
39 *
40 * @param a The first object
41 * @param b The second object
42 * @return True if both objects are equal
43 */
44 static boolean equalsHelper(HasId a, HasId b) {
45 if (a == null && b == null) return true;
46 if (a == null || b == null) return false;
47 return a.getUniqueId().equals(b.getUniqueId());
48 }
49
50 /**
51 * This function calculates the hash code of a list of objects. Only the unique
52 * ID is included in the calculation.
53 *
54 * @param a The list of objects
55 * @return The calculated hash code
56 */
57 static int hashcodeHelper(List<? extends HasId> a) {
58 if (a == null) return 0;
59 final int prime = 31;
60 int result = 1;
61 for (HasId element : a) {
62 result = prime * result + hashcodeHelper(element);
63 }
64 return result;
65 }
66
67 /**
68 * This function calculates the hash code of a object. Only the unique ID is
69 * included in the calculation.
70 *
71 * @param a The object
72 * @return The calculated hash code
73 */
74 static int hashcodeHelper(HasId a) {
75 if (a == null) return 0;
76 return a.getUniqueId().hashCode();
77 }
78 }