Java String类型转换

1、1 字符串转换成数据字符串转换成整数:String MyNumber ="1234"int MyInt = Integer.parseInt(MyNumber;字符串转换成byte, short, int, float, double, long等数据类型,可以分别参考Byte, Short, Integer, Float, Double, Long类的parseXXX方法。A. 有两个方法:1. int i = Integer.parseInt(String; 或i = Integer.parseInt(String,int radix;2. int i = Intege

2、r.valueOf(my_Value(;注: 字串转成Double, Float, Long 的方法大同小异.2 数据转换成字符串整数转换成字符串:int MyInt = 1234;String MyString = "" + MyInt;其它数据类型可以利用同样的方法转换成字符串。1. String s = String.valueOf(i;2. String s = Integer.toString(i;3. String s = "" + i;注: Double, Float, Long 转成字串的方法大同小异.3 十进制到其他进制的

3、转换十进制整数转换成二进制整数,返回结果是一个字符串:Integer.toBinaryString(int i;Integer和Long提供了toBinaryString, toHexString和toOctalString方法,可以方便的将数据转换成二进制、十六进制和八进制字符串。功能更加强大的是其toString(int/long i, int radix方法,可以将一个十进制数转换成任意进制的字符串形式。byte, short, float和double等数据类型,可以利用Integer或者是Long的toBinaryString, toHexString, to OctalString

4、和toString方法转换成其他进制的字符串形式。4 其它进制到十进制的转换五进制字符串14414转换成十进制整数,结果是1234:System.out.println(Integer.valueOf("14414", 5;Integer和Long提供的valueOf(String source, int radix方法,可以将任意进制的字符串转换成十进制数据。5 整数到字节数组的转换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 字节数组到整数的转换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 短整数与字节数

6、组之间的相互转换short与int之间的区别在于short是两个字节的,而int是四个字节的。因此,只需要将5 与6 中的范例程序小做改动,即可实现短整数与字节数组之间的相互转换。8 字节数组转换成双精度浮点数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 布尔类型转换成字符串第一种方法是:boolean bool = true;String s = new Boolean(bool.toString(;/将bool利用对象封装器转化为对象s.equals("true"/* 其中,toString方法是一个继承方法。java中所有的类都是object的继承,object的一个重要方法就是toString,用于将对象转化为字符串。*/第二种方法是:boolean bool = true;Stri

8、ng s = String.valueOf( bool ;首先,从代码长度上讲第二种方法明显要比第一种方法简洁;其次,第一种方法在转化过程中多引入了一个完全没有必要的对象,因此,相对第二种方法来说这就造成了内存空间的浪费,大大减慢了运行速度。所以,推荐使用第二种方法。10 数字类型与数字类对象之间的转换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中常用数据类型转换函数虽然都能在JA VA API中找到,整理一下做个备份。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