(3)--Java_printf_method_quick_referen面向对象程序设计.pdf

Javaprintf()MethodQuickReference

System.out.printf(“format-string”[,arg1,arg2,…]);

FormatString:

Composedofliteralsandformatspecifiers.Argumentsarerequiredonlyifthereareformatspecifiersinthe

formatstring.Formatspecifiersinclude:flags,width,precision,andconversioncharactersinthefollowing

sequence:

%[flags][width][.precision]conversion-character(squarebracketsdenoteoptionalparameters)

Flags:

-:left-justify(defaultistoright-justify)

+:outputaplus(+)orminus(-)signforanumericalvalue

0:forcesnumericalvaluestobezero-padded(defaultisblankpadding)

,:commagroupingseparator(fornumbers1000)

:spacewilldisplayaminussignifthenumberisnegativeoraspaceifitispositive

Width:

Specifiesthefieldwidthforoutputtingtheargumentandrepresentstheminimumnumberofcharactersto

bewrittentotheoutput.Includespaceforexpectedcommasandadecimalpointinthedeterminationof

thewidthfornumericalvalues.

Precision:

Usedtorestricttheoutputdependingontheconversion.Itspecifiesthenumberofdigitsofprecisionwhen

outputtingfloating-pointvaluesorthelengthofasubstringtoextractfromaString.Numbersarerounded

tothespecifiedprecision.

Conversion-Characters:

d:decimalinteger[byte,short,int,long]

f:floating-pointnumber[float,double]

c:characterCapitalCwilluppercasetheletter

s:StringCapitalSwilluppercaseallthelettersinthestring

h:hashcodeAhashcodeislikeanaddress.Thisisusefulforprintingareference

n:newlinePlatformspecificnewlinecharacter-use%ninsteadof\nforgreatercompatibility

Examples:

System.out.printf(Totalis:$%,.2f%n,dblTotal);

System.out.printf(Total:%-10.2f:,dbl