1 import java.util.Collection;
2 import java.util.HashSet;
3 /**
4 * 涓轟粈涔堣鏈?=錛宧ashcode錛宔quels鍛?br /> 5 * hashcode鍙互鎬庝箞鐢?br /> 6 * 浣跨敤鏃跺欏鏄撳拷瑙嗙殑灝忛棶棰?br /> 7 * @author lzz
8 */
9 public class HashCodeTest {
10 public static void main(String[] args) {
11 System.out.println("Test-------1---------");
12 StringTest();
13 //閲嶅啓hashcode鐨勪竴涓渚嬶紝鏈夊彲鑳戒細鏈夎繖縐嶉渶姹?/span>
14 System.out.println("Test-------2--------");
15 CollTest();
16 System.out.println("Test-------3---------");
17 CollTest1();
18 //浣跨敤hashcode鏃跺欐敞鎰忎簨欏癸紝涓涓皬妗堜緥錛屽彲鑳介犳垚鍐呭瓨婧㈠嚭
19 //褰撶劧浣跨敤hashcode鍙互鎻愰珮鏌ヨ鏁堢巼錛岃繖涔熷氨鏄痵et涓轟粈涔堢敤hash綆楁硶鐨勫師鍥犲惂
20 System.out.println("Test-------4---------");
21 CollTest2();
22 }
23
24 public static void StringTest(){
25
26 /* 榪欐槸Object涓殑equels
27 * public boolean equals(Object obj) {
28 return (this == obj);
29 }*/
30 String c=new String("a");
31 String d=new String("a");
32 System.out.println(c.hashCode()==d.hashCode());
33 System.out.println(c==d);
34 System.out.println(c.equals(d));
35 //寮曠敤api涓殑瑙ｉ噴灝辨槸
36 //濡傛灉鏍規嵁 equals(Object) 鏂規硶錛屼袱涓璞℃槸鐩哥瓑鐨勶紝閭ｄ箞瀵硅繖涓や釜瀵硅薄涓殑姣忎釜瀵硅薄璋冪敤 hashCode 鏂規硶閮藉繀欏葷敓鎴愮浉鍚岀殑鏁存暟緇撴灉
37 //鎵浠pi寤鴻閲嶅啓equals鍚屾椂涔熻閲嶅啓hashcode鏂規硶
38 }
39
40 /**
41 * 娌℃湁閲嶅啓hashcode鏂規硶鐨勭被鍦ㄥ姞鍏ashSet鐨勬儏鍐?br /> 42 */
43 public static void CollTest(){
44 Collection coll=new HashSet();
45 CollectionTest coll1=new CollectionTest(3, 4);
46 CollectionTest coll2=new CollectionTest(3, 5);
47 CollectionTest coll3=new CollectionTest(3, 4);
48 coll.add(coll1);
49 coll.add(coll2);
50 coll.add(coll3);
51 System.out.println(coll.size());
52
53 }
54
55 /**
56 * 閲嶅啓hashcode鏂規硶鐨勭被鍦ㄥ姞鍏ashSet鐨勬儏鍐?br /> 57 */
58 public static void CollTest1(){
59 Collection coll=new HashSet();
60 CollectionTest1 coll1=new CollectionTest1(3, 4);
61 CollectionTest1 coll2=new CollectionTest1(3, 5);
62 CollectionTest1 coll3=new CollectionTest1(3, 4);
63 coll.add(coll1);
64 coll.add(coll2);
65 coll.add(coll3);
66 System.out.println(coll.size());
67
68 }
69
70 /**
71 * 濡傛灉榪欐牱浣跨敤浼氶犳垚鍐呭瓨婧㈠嚭闂
72 */
73 public static void CollTest2(){
74 Collection coll=new HashSet();
75 CollectionTest1 coll1=new CollectionTest1(3, 4);
76 CollectionTest1 coll2=new CollectionTest1(3, 5);
77 System.out.println(coll2.hashCode());
78 coll.add(coll1);
79 coll.add(coll2);
80 coll2.x=4;
81 System.out.println(coll2.hashCode());
82 /*褰揷oll2鐨刪ashcode鐢熸垚浠ュ悗鍔犲叆鍒癱oll涓悗錛屾垜浠敼鍙樹粠鏉oll2鐨勫睘鎬э紝姝ゆ椂瀹冪殑hash宸茬粡鍙樺寲浜嗭紝
83 鎵浠ュ綋鎴戜滑鍐嶅幓鍒犻櫎瀹冪殑鏃跺欙紝coll涓瓨鍌ㄧ殑coll2鐨刪ashcod宸茬粡涓嶆槸鍘熸潵鐨勪簡
84 鎵浠ユ渶寮濮嬬殑閭ｄ釜coll2 灝辨病娉曡鍥炴敹錛?nbsp; 濡傛灉榪欐牱鐨勭▼搴忓ぇ閲忓嚭鐜板湪浠ｇ爜涓紝閭ｄ箞鍐呭瓨鏃╂櫄浼氱垎鎺夌殑*/
85
86 coll.remove(coll2);
87 System.out.println(coll.size());
88
89 }
90 }
91 /**
92 * 涓嶉噸鏂板啓hashcode鍜宔quels
93 * @author lzz
94 */
95 class CollectionTest{
96 int x;
97 int y;
98 public CollectionTest(int x,int y){
99 this.x=x;
100 this.y=y;
101 }
102 }
103
104 /**
105 * 閲嶆柊鍐檋ashcode鍜宔quels
106 * @author lzz
107 */
108 class CollectionTest1{
109 int x;
110 int y;
111 public CollectionTest1(int x,int y){
112 this.x=x;
113 this.y=y;
114 }
115 @Override
116 public int hashCode() {
117 final int prime = 31;
118 int result = 1;
119 result = prime * result + x;
120 result = prime * result + y;
121 return result;
122 }
123 @Override
124 public boolean equals(Object obj) {
125 if (this == obj)
126 return true;
127 if (obj == null)
128 return false;
129 if (getClass() != obj.getClass())
130 return false;
131 CollectionTest1 other = (CollectionTest1) obj;
132 if (x != other.x)
133 return false;
134 if (y != other.y)
135 return false;
136 return true;
137 }
138
139 }
140
2 import java.util.HashSet;
3 /**
4 * 涓轟粈涔堣鏈?=錛宧ashcode錛宔quels鍛?br /> 5 * hashcode鍙互鎬庝箞鐢?br /> 6 * 浣跨敤鏃跺欏鏄撳拷瑙嗙殑灝忛棶棰?br /> 7 * @author lzz
8 */
9 public class HashCodeTest {
10 public static void main(String[] args) {
11 System.out.println("Test-------1---------");
12 StringTest();
13 //閲嶅啓hashcode鐨勪竴涓渚嬶紝鏈夊彲鑳戒細鏈夎繖縐嶉渶姹?/span>
14 System.out.println("Test-------2--------");
15 CollTest();
16 System.out.println("Test-------3---------");
17 CollTest1();
18 //浣跨敤hashcode鏃跺欐敞鎰忎簨欏癸紝涓涓皬妗堜緥錛屽彲鑳介犳垚鍐呭瓨婧㈠嚭
19 //褰撶劧浣跨敤hashcode鍙互鎻愰珮鏌ヨ鏁堢巼錛岃繖涔熷氨鏄痵et涓轟粈涔堢敤hash綆楁硶鐨勫師鍥犲惂
20 System.out.println("Test-------4---------");
21 CollTest2();
22 }
23
24 public static void StringTest(){
25
26 /* 榪欐槸Object涓殑equels
27 * public boolean equals(Object obj) {
28 return (this == obj);
29 }*/
30 String c=new String("a");
31 String d=new String("a");
32 System.out.println(c.hashCode()==d.hashCode());
33 System.out.println(c==d);
34 System.out.println(c.equals(d));
35 //寮曠敤api涓殑瑙ｉ噴灝辨槸
36 //濡傛灉鏍規嵁 equals(Object) 鏂規硶錛屼袱涓璞℃槸鐩哥瓑鐨勶紝閭ｄ箞瀵硅繖涓や釜瀵硅薄涓殑姣忎釜瀵硅薄璋冪敤 hashCode 鏂規硶閮藉繀欏葷敓鎴愮浉鍚岀殑鏁存暟緇撴灉
37 //鎵浠pi寤鴻閲嶅啓equals鍚屾椂涔熻閲嶅啓hashcode鏂規硶
38 }
39
40 /**
41 * 娌℃湁閲嶅啓hashcode鏂規硶鐨勭被鍦ㄥ姞鍏ashSet鐨勬儏鍐?br /> 42 */
43 public static void CollTest(){
44 Collection coll=new HashSet();
45 CollectionTest coll1=new CollectionTest(3, 4);
46 CollectionTest coll2=new CollectionTest(3, 5);
47 CollectionTest coll3=new CollectionTest(3, 4);
48 coll.add(coll1);
49 coll.add(coll2);
50 coll.add(coll3);
51 System.out.println(coll.size());
52
53 }
54
55 /**
56 * 閲嶅啓hashcode鏂規硶鐨勭被鍦ㄥ姞鍏ashSet鐨勬儏鍐?br /> 57 */
58 public static void CollTest1(){
59 Collection coll=new HashSet();
60 CollectionTest1 coll1=new CollectionTest1(3, 4);
61 CollectionTest1 coll2=new CollectionTest1(3, 5);
62 CollectionTest1 coll3=new CollectionTest1(3, 4);
63 coll.add(coll1);
64 coll.add(coll2);
65 coll.add(coll3);
66 System.out.println(coll.size());
67
68 }
69
70 /**
71 * 濡傛灉榪欐牱浣跨敤浼氶犳垚鍐呭瓨婧㈠嚭闂
72 */
73 public static void CollTest2(){
74 Collection coll=new HashSet();
75 CollectionTest1 coll1=new CollectionTest1(3, 4);
76 CollectionTest1 coll2=new CollectionTest1(3, 5);
77 System.out.println(coll2.hashCode());
78 coll.add(coll1);
79 coll.add(coll2);
80 coll2.x=4;
81 System.out.println(coll2.hashCode());
82 /*褰揷oll2鐨刪ashcode鐢熸垚浠ュ悗鍔犲叆鍒癱oll涓悗錛屾垜浠敼鍙樹粠鏉oll2鐨勫睘鎬э紝姝ゆ椂瀹冪殑hash宸茬粡鍙樺寲浜嗭紝
83 鎵浠ュ綋鎴戜滑鍐嶅幓鍒犻櫎瀹冪殑鏃跺欙紝coll涓瓨鍌ㄧ殑coll2鐨刪ashcod宸茬粡涓嶆槸鍘熸潵鐨勪簡
84 鎵浠ユ渶寮濮嬬殑閭ｄ釜coll2 灝辨病娉曡鍥炴敹錛?nbsp; 濡傛灉榪欐牱鐨勭▼搴忓ぇ閲忓嚭鐜板湪浠ｇ爜涓紝閭ｄ箞鍐呭瓨鏃╂櫄浼氱垎鎺夌殑*/
85
86 coll.remove(coll2);
87 System.out.println(coll.size());
88
89 }
90 }
91 /**
92 * 涓嶉噸鏂板啓hashcode鍜宔quels
93 * @author lzz
94 */
95 class CollectionTest{
96 int x;
97 int y;
98 public CollectionTest(int x,int y){
99 this.x=x;
100 this.y=y;
101 }
102 }
103
104 /**
105 * 閲嶆柊鍐檋ashcode鍜宔quels
106 * @author lzz
107 */
108 class CollectionTest1{
109 int x;
110 int y;
111 public CollectionTest1(int x,int y){
112 this.x=x;
113 this.y=y;
114 }
115 @Override
116 public int hashCode() {
117 final int prime = 31;
118 int result = 1;
119 result = prime * result + x;
120 result = prime * result + y;
121 return result;
122 }
123 @Override
124 public boolean equals(Object obj) {
125 if (this == obj)
126 return true;
127 if (obj == null)
128 return false;
129 if (getClass() != obj.getClass())
130 return false;
131 CollectionTest1 other = (CollectionTest1) obj;
132 if (x != other.x)
133 return false;
134 if (y != other.y)
135 return false;
136 return true;
137 }
138
139 }
140
orangle_lzz 2012-09-11 17:31 鍙戣〃璇勮
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