Java String類型轉(zhuǎn)換

1、1 字符串轉(zhuǎn)換成數(shù)據(jù)字符串轉(zhuǎn)換成整數(shù):String MyNumber ="1234"int MyInt = Integer.parseInt(MyNumber;字符串轉(zhuǎn)換成byte, short, int, float, double, long等數(shù)據(jù)類型,可以分別參考Byte, Short, Integer, Float, Double, Long類的parseXXX方法。A. 有兩個(gè)方法:1. int i = Integer.parseInt(String; 或i = Integer.parseInt(String,int radix;2. int i = Intege

2、r.valueOf(my_Value(;注: 字串轉(zhuǎn)成Double, Float, Long 的方法大同小異.2 數(shù)據(jù)轉(zhuǎn)換成字符串整數(shù)轉(zhuǎn)換成字符串:int MyInt = 1234;String MyString = "" + MyInt;其它數(shù)據(jù)類型可以利用同樣的方法轉(zhuǎn)換成字符串。1. String s = String.valueOf(i;2. String s = Integer.toString(i;3. String s = "" + i;注: Double, Float, Long 轉(zhuǎn)成字串的方法大同小異.3 十進(jìn)制到其他進(jìn)制的

3、轉(zhuǎn)換十進(jìn)制整數(shù)轉(zhuǎn)換成二進(jìn)制整數(shù),返回結(jié)果是一個(gè)字符串:Integer.toBinaryString(int i;Integer和Long提供了toBinaryString, toHexString和toOctalString方法,可以方便的將數(shù)據(jù)轉(zhuǎn)換成二進(jìn)制、十六進(jìn)制和八進(jìn)制字符串。功能更加強(qiáng)大的是其toString(int/long i, int radix方法,可以將一個(gè)十進(jìn)制數(shù)轉(zhuǎn)換成任意進(jìn)制的字符串形式。byte, short, float和double等數(shù)據(jù)類型,可以利用Integer或者是Long的toBinaryString, toHexString, to OctalString

4、和toString方法轉(zhuǎn)換成其他進(jìn)制的字符串形式。4 其它進(jìn)制到十進(jìn)制的轉(zhuǎn)換五進(jìn)制字符串14414轉(zhuǎn)換成十進(jìn)制整數(shù),結(jié)果是1234:System.out.println(Integer.valueOf("14414", 5;Integer和Long提供的valueOf(String source, int radix方法,可以將任意進(jìn)制的字符串轉(zhuǎn)換成十進(jìn)制數(shù)據(jù)。5 整數(shù)到字節(jié)數(shù)組的轉(zhuǎn)換public static byte toByteArray(int numberint temp = number;byte b=new byte4;for (int i = b.lengt

5、h - 1; i > -1; i-bi = new Integer(temp & 0xff.byteValue(;temp = temp >> 8;return b;6 字節(jié)數(shù)組到整數(shù)的轉(zhuǎn)換public static int toInteger(byte bint s = 0;for (int i = 0; i < 3; i+if (bi > 0s = s + bi;elses = s + 256 + bi;s = s * 256;if (b3 > 0s = s + b3;elses = s + 256 + b3;return s;7 短整數(shù)與字節(jié)數(shù)

6、組之間的相互轉(zhuǎn)換short與int之間的區(qū)別在于short是兩個(gè)字節(jié)的,而int是四個(gè)字節(jié)的。因此,只需要將5 與6 中的范例程序小做改動(dòng),即可實(shí)現(xiàn)短整數(shù)與字節(jié)數(shù)組之間的相互轉(zhuǎn)換。8 字節(jié)數(shù)組轉(zhuǎn)換成雙精度浮點(diǎn)數(shù)public double toDouble(byte blong l = 0;Double D = new Double(0.0;l = b0;l |= (longb1<<8;l |= (longb2<<16;l |= (longb3<<24;l |= (longb4<<32;l |= (longb5<<40;l |= (lo

7、ngb6<<48;l |= (longb7<<56;return D.longBitsToDouble(l;9 布爾類型轉(zhuǎn)換成字符串第一種方法是:boolean bool = true;String s = new Boolean(bool.toString(;/將bool利用對(duì)象封裝器轉(zhuǎn)化為對(duì)象s.equals("true"/* 其中,toString方法是一個(gè)繼承方法。java中所有的類都是object的繼承,object的一個(gè)重要方法就是toString,用于將對(duì)象轉(zhuǎn)化為字符串。*/第二種方法是:boolean bool = true;Stri

8、ng s = String.valueOf( bool ;首先,從代碼長(zhǎng)度上講第二種方法明顯要比第一種方法簡(jiǎn)潔;其次,第一種方法在轉(zhuǎn)化過(guò)程中多引入了一個(gè)完全沒(méi)有必要的對(duì)象,因此,相對(duì)第二種方法來(lái)說(shuō)這就造成了內(nèi)存空間的浪費(fèi),大大減慢了運(yùn)行速度。所以,推薦使用第二種方法。10 數(shù)字類型與數(shù)字類對(duì)象之間的轉(zhuǎn)換byte b = 169;Byte bo = new Byte( b ;b = bo.byteValue(;short t = 169;Short to = new Short( t ;t = to.shortValue(;int i = 169;Integer io = new Integer

9、( i ;i = Value(;long l = 169;Long lo = new Long( l ;l = lo.longValue(;float f = 169f;Float fo = new Float( f ;f = fo.floatValue(;double d = 169f;Double dObj = new Double( d ;d = dObj.doubleValue(;* *package .lwkj.erts.register;import java.sql.Date;public class TypeChange public TypeChange( /ch

10、ange the string type to the int typepublic static int stringToInt(String intstrInteger integer;integer = Integer.valueOf(intstr;return Value(;/change int type to the string typepublic static String intToString(int valueInteger integer = new Integer(value;return integer.toString(;/change t

11、he string type to the float typepublic static float stringToFloat(String floatstrFloat floatee;floatee = Float.valueOf(floatstr;return floatee.floatV alue(;/change the float type to the string typepublic static String floatToString(float valueFloat floatee = new Float(value;return floatee.toString(;

12、/change the string type to the sqlDate typepublic static java.sql.Date stringToDate(String dateStr return java.sql.Date.valueOf(dateStr;/change the sqlDate type to the string typepublic static String dateToString(java.sql.Date datee return datee.toString(;public static void main(String argsjava.sql.

13、Date day ;day = TypeChange.stringToDate("2003-11-3"String strday = TypeChange.dateToString(day;System.out.println(strday;JA V A中常用數(shù)據(jù)類型轉(zhuǎn)換函數(shù)雖然都能在JA VA API中找到,整理一下做個(gè)備份。string->byteByte static byte parseByte(String sbyte->stringByte static String toString(byte bchar->stringCharacter s

14、tatic String to String (char cstring->ShortShort static Short parseShort(String sShort->StringShort static String toString(Short sString->Integer Integer static int parseInt(String s Integer->String Integer static String tostring(int i String->Long Long static long parseLong(String s

15、Long->String Long static String toString(Long i String->Float Float static float parseFloat(String s Float->String Float static String toString(float f String->Double Double static double parseDouble(String s Double->String Double static String toString(Double * * string->byte Byte

16、 static byte parseByte(String s byte->string Byte static String toString(byte b char->string Character static String to String (char c string->Short Short static Short parseShort(String s Short->String Short static String toString(Short s String->Integer Integer static int parseInt(String s Integer->String Integer static String tostring(int i String->Long Long static long parseLong(String s Long->String Lo