Objects婧愮爜瑙ｈ

Posted 2020-11-27

鏍囩锛?a href='http://www.mamicode.com/so/1/field' title='field'>field   help   arrays   returns   money   閬垮厤   stat   plain   ||   

1.equal()鏂规硶

Objects.equal鏂规硶鍙互閬垮厤jdk鐨別qual()鏂规硶鐨勫璞′负null鏃舵姏鍑虹┖鎸囬拡銆?/p>

1  Objects.equal("a", "a"); // returns true
2  Objects.equal(null, "a"); // returns false
3  Objects.equal("a", null); // returns false
4  Objects.equal(null, null); // returns true

鍏朵腑鐨勬簮鐮佸疄鐜颁负锛?/p>

1  public static boolean equal(@Nullable Object a, @Nullable Object b) {
2         return a == b || a != null && a.equals(b);
3     }

2.hash()绠楁硶

鐢ㄥ璞＄殑鎵€鏈夊瓧娈典綔鏁ｅ垪[hash]杩愮畻锛孏uava鐨?tt>Objects.hashCode(Object...)浼氬浼犲叆鐨勫瓧娈靛簭鍒楄绠楀嚭鍚堢悊鐨勩€侀『搴忔晱鎰熺殑鏁ｅ垪鍊笺€備綘鍙互浣跨敤Objects.hashCode(field1, field2, …, fieldn)鏉ヤ唬鏇挎墜鍔ㄨ绠楁暎鍒楀€笺€?/p>

 1  public static int hashCode(@Nullable Object... objects) {
 2         return Arrays.hashCode(objects);
 3     }
 4 
 5  public static int hashCode(Object a[]) {
 6         if (a == null)
 7             return 0;
 8 
 9         int result = 1;
10 
11         for (Object element : a)
12             result = 31 * result + (element == null ? 0 : element.hashCode());
13 
14         return result;
15     }

3.toString()鏂规硶

濂界殑toString鏂规硶鍦ㄨ皟璇曟椂鏄棤浠蜂箣瀹濓紝浣嗘槸缂栧啓toString鏂规硶鏈夋椂鍊欏嵈寰堢棝鑻︺€備娇鐢?nbsp;Objects.toStringHelper鍙互杞绘澗缂栧啓鏈夌敤鐨則oString鏂规硶銆備緥濡傦細

Objects.toStringHelper(this).add("x", 1).toString();

Objects.toStringHelper("MyObject").add("x", 1).toString();

娉細搴曞眰浣跨敤涓€涓崟鍚戦摼琛ㄦ潵娣诲姞鍏冪礌銆?/p>

 1 public String toString() {
 2             boolean omitNullValuesSnapshot = this.omitNullValues;
 3             String nextSeparator = "";
 4             StringBuilder builder = (new StringBuilder(32)).append(this.className).append(鈥榹鈥?span style="color: #000000;">);
 5 
 6             for(Objects.ToStringHelper.ValueHolder valueHolder = this.holderHead.next; valueHolder != null; valueHolder = valueHolder.next) {
 7                 if (!omitNullValuesSnapshot || valueHolder.value != null) {
 8                     builder.append(nextSeparator);
 9                     nextSeparator = ", ";
10                     if (valueHolder.name != null) {
11                         builder.append(valueHolder.name).append(鈥?鈥?span style="color: #000000;">);
12                     }
13 
14                     builder.append(valueHolder.value);
15                 }
16             }
17 
18  private static final class ValueHolder {
19             String name;
20             Object value;
21             Objects.ToStringHelper.ValueHolder next;
22 
23             private ValueHolder() {
24             }
25         }

4.缁ф壙Comparable鎺ュ彛

Guava鎻愪緵浜咰omparisonChain鎵ц涓€绉嶆噿姣旇緝锛氬畠鎵ц姣旇緝鎿嶄綔鐩磋嚦鍙戠幇闈為浂鐨勭粨鏋滐紝灏嗚繑鍥炶绠楃粨鏋滐紝鍦ㄩ偅涔嬪悗鐨勬瘮杈冭緭鍏ュ皢琚拷鐣ャ€?/p>

1 @Override
2     public int compareTo(Account o) {
3         return ComparisonChain.start()
4                 .compare(this.accountName, o.accountName)
5                 .compare(this.money, o.money).result();
6     }

 

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