String uuid1 = UUID.randomUUID().toString();
Log.e(TAG, "uuid1 默认的uuid: "+uuid1);
String uuid2 = UUID.randomUUID().toString().replace("-","");//格式化UUID将“-”去掉
Log.e(TAG, "uuid2 将“-”去掉: "+uuid2);
String uuid3 = UUID.randomUUID().toString().replace("-",".");//格式UUID将“-”格式成“.”
Log.e(TAG, "uuid3 将“-”格式成“.”: "+uuid3);
String uuid4 = UUID.randomUUID().toString().concat(".apk");//格式UUID,在UUID的结尾添加.apk
Log.e(TAG, "uuid4 结尾添加.apk: "+uuid4);
String uuid5 = UUID.randomUUID().toString().replaceAll("\\d","");//替换所有,参数1为要替换的字符正则表达式,参数2为替换字符;
Log.e(TAG, "uuid5 去掉所有数字: "+uuid5);
UUID newuuid = UUID.fromString(uuid1);//将String类型 转成 UUID
UUID u1 = UUID.randomUUID();
UUID u2 = UUID.randomUUID();
int values = u1.compareTo(u2); // -1=小于 0=等于 1=大于
Log.e(TAG, "u1 对比 u2: "+values);//注意UUID对比 不会根据生成时间就比较大,它只是简单的比较字符大小
结果:
08-16 14:54:27.134 18951-18951/yt.yunwatch E/DemoActivity: uuid1 默认的uuid: 02f33031-dbb6-465f-9645-11388b3f08c6
08-16 14:54:27.135 18951-18951/yt.yunwatch E/DemoActivity: uuid2 将“-”去掉: f7b60f9a76954939afd773c158527b99
08-16 14:54:27.135 18951-18951/yt.yunwatch E/DemoActivity: uuid3 将“-”格式成“.”: 2c5c2843.a122.465b.bb23.963221fb32ed
08-16 14:54:27.136 18951-18951/yt.yunwatch E/DemoActivity: uuid4 结尾添加.apk: f466f910-0ed9-4a26-8532-bee14272136f.apk
08-16 14:54:27.137 18951-18951/yt.yunwatch E/DemoActivity: uuid5 去掉所有数字: fdb-ca-d-b-cfaee
08-16 14:54:27.138 18951-18951/yt.yunwatch E/DemoActivity: u1 对比 u2: -1
Java格式化时间到毫秒:
SimpleDateFormat formatter = new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss:SSS");
String formatStr =formatter.format(new Date();
附录:
java格式化字母表
Symbol | Meaning | Presentation | Example |
---|---|---|---|
G | era designator | Text | AD |
y | year | Number | 2009 |
M | month in year | Text & Number | July & 07 |
d | day in month | Number | 10 |
h | hour in am/pm (1-12) | Number | 12 |
H | hour in day (0-23) | Number | 0 |
m | minute in hour | Number | 30 |
s | second in minute | Number | 55 |
S | millisecond | Number | 978 |
E | day in week | Text | Tuesday |
D | day in year | Number | 189 |
F | day of week in month | Number | 2 (2nd Wed in July) |
w | week in year | Number | 27 |
W | week in month | Number | 2 |
a | am/pm marker | Text | PM |
k | hour in day (1-24) | Number | 24 |
K | hour in am/pm (0-11) | Number | 0 |
z | time zone | Text | Pacific Standard Time |
' | escape for text | Delimiter | (none) |
' | single quote | Literal | ' |