Java Data Types - W3Schools

A primitive data type specifies the size and type of variable values, and it has no additional methods. There are eight primitive data types in Java: ... 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JavaHowTo AddTwoNumbers JavaReference JavaKeywords abstract boolean break byte case catch char class continue default do double else enum extends final finally float for if implements import instanceof int interface long new package private protected public return short static super switch this throw throws try void while JavaStringMethods JavaMathMethods JavaExamples JavaExamples JavaCompiler JavaExercises JavaQuiz JavaCertificate JavaDataTypes ❮Previous Next❯ JavaDataTypes Asexplainedinthepreviouschapter,avariableinJavamustbeaspecifieddatatype: Example intmyNum=5;              //Integer(wholenumber) floatmyFloatNum=5.99f;   //Floatingpointnumber charmyLetter='D';        //Character booleanmyBool=true;      //Boolean StringmyText="Hello";    //String TryitYourself» Datatypesaredividedintotwogroups: Primitivedatatypes-includesbyte,short,int,long, float,double,booleanandchar Non-primitivedatatypes-suchasString,ArraysandClasses(youwilllearnmoreabouttheseinalaterchapter) PrimitiveDataTypes Aprimitivedatatypespecifiesthesizeandtypeofvariablevalues,andithasno additionalmethods. ThereareeightprimitivedatatypesinJava: DataType Size Description byte 1byte Storeswholenumbersfrom-128to127 short 2bytes Storeswholenumbersfrom-32,768to32,767 int 4bytes Storeswholenumbersfrom-2,147,483,648to2,147,483,647 long 8bytes Storeswholenumbersfrom-9,223,372,036,854,775,808to 9,223,372,036,854,775,807 float 4bytes Storesfractionalnumbers.Sufficientfor storing6to7decimaldigits double 8bytes Storesfractionalnumbers.Sufficientfor storing15decimaldigits boolean 1bit Storestrueorfalsevalues char 2bytes Storesasinglecharacter/letterorASCIIvalues Numbers Primitivenumbertypesaredividedintotwogroups: Integertypesstoreswholenumbers,positiveornegative(suchas123or-456),withoutdecimals. Validtypesarebyte,short,int andlong.Whichtypeyoushoulduse,dependsonthenumericvalue. Floatingpointtypesrepresentsnumberswithafractionalpart, containingoneormoredecimals.Therearetwotypes:floatanddouble. EventhoughtherearemanynumerictypesinJava,themostusedfornumbers areint(forwholenumbers)anddouble(forfloatingpointnumbers).However,wewilldescribethemallasyoucontinueto read. IntegerTypes Byte Thebytedatatypecanstorewholenumbers from-128to127.Thiscanbeusedinsteadofintorotherintegertypesto savememorywhenyouarecertainthatthevaluewillbewithin-128and127: Example bytemyNum=100; System.out.println(myNum); TryitYourself» Short Theshortdatatypecanstorewholenumbersfrom-32768to32767: Example shortmyNum=5000; System.out.println(myNum); TryitYourself» Int Theintdatatypecanstorewholenumbersfrom-2147483648to2147483647.Ingeneral,andinourtutorial,theintdatatypeis thepreferreddatatypewhenwecreatevariableswithanumericvalue. Example intmyNum=100000; System.out.println(myNum); TryitYourself» Long Thelongdatatypecanstorewholenumbersfrom-9223372036854775808to9223372036854775807.Thisisusedwhenintisnotlargeenoughtostorethevalue.Notethatyoushouldendthevaluewithan"L": Example longmyNum=15000000000L; System.out.println(myNum); TryitYourself» FloatingPointTypes Youshoulduseafloatingpointtypewheneveryouneedanumberwithadecimal,suchas9.99or3.14515. Float Thefloatdatatypecanstorefractionalnumbersfrom3.4e−038to3.4e+038.Notethatyoushouldendthevaluewithan"f": Example floatmyNum=5.75f; System.out.println(myNum); TryitYourself» Double Thedoubledatatypecanstorefractionalnumbersfrom1.7e−308to1.7e+308.Notethatyoushouldendthevaluewitha"d": Example doublemyNum=19.99d; System.out.println(myNum); TryitYourself» Usefloatordouble? Theprecisionofafloatingpointvalueindicateshowmanydigitsthevaluecanhave afterthedecimalpoint. Theprecisionoffloatisonlysixorseven decimaldigits,whiledoublevariableshaveaprecision ofabout15digits.Thereforeitissafertousedoubleformostcalculations. ScientificNumbers Afloatingpointnumbercanalsobeascientificnumberwithan"e"toindicatethepowerof10: Example floatf1=35e3f; doubled1=12E4d; System.out.println(f1); System.out.println(d1); TryitYourself» Booleans Abooleandatatypeisdeclaredwiththebooleankeywordandcanonlytakethevaluestrueorfalse: Example booleanisJavaFun=true; booleanisFishTasty=false; System.out.println(isJavaFun);    //Outputstrue System.out.println(isFishTasty);  //Outputsfalse TryitYourself» Booleanvaluesaremostlyusedforconditionaltesting,whichyouwilllearnmoreaboutinalaterchapter. Characters Thechardatatypeisusedtostorea singlecharacter.Thecharactermustbe surroundedbysinglequotes,like'A'or'c': Example charmyGrade='B'; System.out.println(myGrade); TryitYourself» Alternatively,youcanuseASCIIvaluestodisplaycertaincharacters: Example charmyVar1=65,myVar2=66,myVar3=67; System.out.println(myVar1); System.out.println(myVar2); System.out.println(myVar3); TryitYourself» Tip:AlistofallASCIIvaluescanbefoundinourASCIITableReference. Strings TheStringdatatypeisusedtostoreasequenceofcharacters(text).Stringvaluesmustbesurroundedbydoublequotes: Example Stringgreeting="HelloWorld"; System.out.println(greeting); TryitYourself» TheStringtypeissomuchusedandintegratedinJava,thatsomecallit"thespecial ninthtype". AStringinJavaisactuallyanon-primitivedatatype,becauseitrefersto anobject.TheStringobjecthasmethodsthatareusedtoperformcertain operationsonstrings.Don'tworryifyoudon'tunderstandtheterm"object"justyet.Wewilllearnmoreaboutstringsandobjectsinalaterchapter. Non-PrimitiveDataTypes Non-primitivedatatypesarecalledreferencetypesbecause theyrefertoobjects. Themaindifferencebetweenprimitiveandnon-primitivedatatypesare: Primitivetypesarepredefined(alreadydefined)inJava.Non-primitivetypesarecreatedbytheprogrammerand isnotdefinedbyJava(exceptforString). Non-primitivetypescanbeusedtocallmethodstoperformcertainoperations,whileprimitivetypescannot. Aprimitivetypehasalwaysavalue,whilenon-primitivetypescanbenull. Aprimitivetypestartswithalowercaseletter,whilenon-primitivetypesstartswithanuppercaseletter. Thesizeofaprimitivetypedependsonthedatatype,whilenon-primitivetypeshaveallthesamesize. Examplesofnon-primitivetypesareStrings,Arrays,Classes,Interface,etc.Youwilllearnmoreabouttheseinalaterchapter. TestYourselfWithExercises Exercise: Addthecorrectdatatypeforthefollowingvariables: myNum=9; myFloatNum=8.99f; myLetter='A'; myBool=false; myText="HelloWorld"; SubmitAnswer» StarttheExercise ❮Previous Next❯ NEW WejustlaunchedW3Schoolsvideos Explorenow COLORPICKER Getcertifiedbycompletingacoursetoday! w3schoolsCERTIFIED.2021 Getstarted CODEGAME PlayGame