Java The Complete Reference, Seventh Edition

396 Part II: The Java Library

Converting Numbers to and from Strings

One of the most common programming chores is converting the string representation of a

number into its internal, binary format. Fortunately, Java provides an easy way to accomplish

this. TheByte,Short,Integer, andLongclasses provide theparseByte( ),parseShort( ),

parseInt( ), andparseLong( )methods, respectively. These methods return thebyte,short,

Method Description

static long parseLong(Stringstr)

throws NumberFormatException

Returns thelongequivalent of the number

contained in the string specified bystrin radix 10.

static long parseLong(Stringstr, intradix)

throws NumberFormatException

Returns thelongequivalent of the number contained

in the string specified bystrusing the specifiedradix.

static long reverse(longnum) Reverses the order of the bits innumand returns

the result.

static long reverseBytes(longnum) Reverses the order of the bytes innumand returns

the result.

static long rotateLeft(longnum, intn) Returns the result of rotatingnumleftnpositions.

static long rotateRight(longnum, intn) Returns the result of rotatingnumrightnpositions.

static int signum(longnum) Returns –1 ifnumis negative, 0 if it is zero, and 1 if

it is positive.

short shortValue( ) Returns the value of the invoking object as ashort.

static String toBinar yString(longnum) Returns a string that contains the binar y equivalent

ofnum.

static String toHexString(longnum) Returns a string that contains the hexadecimal

equivalent ofnum.

static String toOctalString(longnum) Returns a string that contains the octal equivalent

ofnum.

String toString( ) Returns a string that contains the decimal equivalent

of the invoking object.

static String toString(longnum) Returns a string that contains the decimal equivalent

ofnum.

static String toString(longnum, intradix) Returns a string that contains the decimal equivalent

ofnumusing the specifiedradix.

static Long valueOf(longnum) Returns aLongobject containing the value passed

innum.

static Long valueOf(Stringstr)

throws NumberFormatException

Returns aLongobject that contains the value

specified by the string instr.

static Long valueOf(Stringstr, intradix)

throws NumberFormatException

Returns aLongobject that contains the value

specified by the string instrusing the specifiedradix.

TABLE 16-6 The Methods Defined byLong(continued)