1、ISO-639 定義了語言代碼， Common ISO-639 Language Codes
?? 而ISO-3166定義了國家代碼 ，Common ISO-3166 Country Codes
2、boxing 問題：
(from JSR 5.1.7):
If the value p being
boxed is
true, false, a byte, a char in the range
\u0000 to \u007f, or an int or short number between -128 and
127, then let r1 and r2 be the results of any two boxing conversions of
p. It is always the case that r1 == r2.
因此，下面一個例子
AutoBoxing.java
import?java.util.*;
public?class?AutoBoxing
{
????public?static?void?main(String?[]?args)
????{
????????List<Integer>?bigs?=?Arrays.asList(100,?200,?300);
????????assert?sumInteger(bigs)?==?sum(bigs);
????????assert?sumInteger(bigs)?!=?sumInteger(bigs);
????????
????????List<Integer>?smalls?=?Arrays.asList(1,?2,?3);
????????assert?sumInteger(smalls)?==?sum(smalls);
????????assert?sumInteger(smalls)?==?sumInteger(smalls);
????????
????????for?(int?i=-129;?i<129;?i++)
????????{
????????????Integer?small_1?=?i;
????????????Integer?small_2?=?i;
????????????System.out.println((small_1?==?small_2)?+?"??"?+?i);
????????}
????}
????
????public?static?int?sum(List<Integer>?ints)
????{
????????int?s?=?0;
????????for?(int?n?:?ints)
????????????s?+=?n;
????????return?s;
????}
????
????public?static?Integer?sumInteger(List<Integer>?ints)
????{
????????Integer?s?=?0;
????????for?(Integer?n?:?ints)
????????????s?+=?n;
????????return?s;
????}????
}而其運行結果為：
運行結果
false??-129
true??-128
true??-127
true??-126
true??-125
true??-124
true??-123
true??-122
true??-121
true??-120
true??-119
true??-118
true??-117
true??-116
true??-115
true??-114
true??-113
true??-112
true??-111
true??-110
true??-109
true??-108
true??-107
true??-106
true??-105
true??-104
true??-103
true??-102
true??-101
true??-100
true??-99
true??-98
true??-97
true??-96
true??-95
true??-94
true??-93
true??-92
true??-91
true??-90
true??-89
true??-88
true??-87
true??-86
true??-85
true??-84
true??-83
true??-82
true??-81
true??-80
true??-79
true??-78
true??-77
true??-76
true??-75
true??-74
true??-73
true??-72
true??-71
true??-70
true??-69
true??-68
true??-67
true??-66
true??-65
true??-64
true??-63
true??-62
true??-61
true??-60
true??-59
true??-58
true??-57
true??-56
true??-55
true??-54
true??-53
true??-52
true??-51
true??-50
true??-49
true??-48
true??-47
true??-46
true??-45
true??-44
true??-43
true??-42
true??-41
true??-40
true??-39
true??-38
true??-37
true??-36
true??-35
true??-34
true??-33
true??-32
true??-31
true??-30
true??-29
true??-28
true??-27
true??-26
true??-25
true??-24
true??-23
true??-22
true??-21
true??-20
true??-19
true??-18
true??-17
true??-16
true??-15
true??-14
true??-13
true??-12
true??-11
true??-10
true??-9
true??-8
true??-7
true??-6
true??-5
true??-4
true??-3
true??-2
true??-1
true??0
true??1
true??2
true??3
true??4
true??5
true??6
true??7
true??8
true??9
true??10
true??11
true??12
true??13
true??14
true??15
true??16
true??17
true??18
true??19
true??20
true??21
true??22
true??23
true??24
true??25
true??26
true??27
true??28
true??29
true??30
true??31
true??32
true??33
true??34
true??35
true??36
true??37
true??38
true??39
true??40
true??41
true??42
true??43
true??44
true??45
true??46
true??47
true??48
true??49
true??50
true??51
true??52
true??53
true??54
true??55
true??56
true??57
true??58
true??59
true??60
true??61
true??62
true??63
true??64
true??65
true??66
true??67
true??68
true??69
true??70
true??71
true??72
true??73
true??74
true??75
true??76
true??77
true??78
true??79
true??80
true??81
true??82
true??83
true??84
true??85
true??86
true??87
true??88
true??89
true??90
true??91
true??92
true??93
true??94
true??95
true??96
true??97
true??98
true??99
true??100
true??101
true??102
true??103
true??104
true??105
true??106
true??107
true??108
true??109
true??110
true??111
true??112
true??113
true??114
true??115
true??116
true??117
true??118
true??119
true??120
true??121
true??122
true??123
true??124
true??125
true??126
true??127
false??128
應盡量使用equals()而不是 == 來應用于諸如 Integer， String之類的比較