2023学年完整公开课版datatypes

DataTypesProblemJava：FourkindsofeightkindsofdatatypesIntheJavalanguage,howmanytypesofdataarethere?Alittlesisterwenttothesupermarkettobuyfruits.Itisknownthatapplesare7.5yuanacatty,pearsare6yuanacatty,andthelittlesisterwantstobuy2cattiesofapplesand3cattiesofpears.MayIaskthissisterbroughtatotalof50yuan,isitenough?Totalpriceofpears：6*3=18(yuan)Totalpriceofapples：7.5*2=15(yuan)Totalfruitsprice：18+15=33(元)33<50，enough！BasicDataTypesBasicdatatypes整型布尔型浮点型字符型charbooleanfloatdoublebyteshortintlongJava

Keywords

Keywordsarepre-definedEnglishwordswithspecialmeanings.Sometimestheyarealsocalledreservedwords.Theyhavespecialmeaningstothecompilerandcannotbeusedforotherpurposes.alllowercaseTheFirstType:Integername

oftypebytesoccupiedbitsoccupiedrangesbyte18-27~27-1(-128~127)short216-215~215-1(-32768~32767)int432-231~231-1(-2147483648~2147483647)long864-263~263-1Conclusion:Fromtoptobottom,therangeofnumbersexpressedisgettinglargerandlarger.1byte1bit:binarynumber0or1TheFirstType:IntegerAlittlesisterwenttothesupermarkettobuyfruits.Itisknownthatapplesare7.5yuanacatty,pearsare6yuanacatty,andthelittlesisterwantstobuy2cattiesofapplesand3cattiesofpears.MayIaskthissisterbroughtatotalof50yuan,isitenough?Totalpriceofpears：6*3=18(元)TheSecondType:FloatingPoint二元图表floatDatatypewithfractionalpart.Single-precisionfloating-pointtype,whichisrepresentedby4bytesisequalto32bits.Range：-3.4*1038~3.4*1038doubleDatatypewithfractionalpart.Thedouble-precisionfloating-pointtypeisrepresentedby8bytesisequalto64bits.Range：-1.7*10308~1.7*10308TheSecondType:FloatingPoint二元图表Alittlesisterwenttothesupermarkettobuyfruits.Itisknownthatapplesare7.5yuanacatty,pearsare6yuanacatty,andthelittlesisterwantstobuy2cattiesofapplesand3cattiesofpears.MayIaskthissisterbroughtatotalof50yuan,isitenough?TheThirdType:CharacterTypeThecharactertypecharisusedtorepresentasinglecharacter,suchasletters,numbers,punctuationmarks,andothersymbols.pearsapplesTheFourthType：BooleanThebooleantypeisusedtorepresentthevalueofoneofthetwologicstates,andthevaluesareonlytrueandfalse.Isitenough？Isitgood？Isityes？Totalpriceofpears：6*3=18(元)Totalpriceofapples：7.5*2=15(元)Totalfruitsprice：18+15=33(元)33<50，enough！trueDataTypeConversionPriorityWhendifferenttypesofdataaremixedThesystemneedstoconvertlowprioritynumberstohigherprioritynumbersaccordingtovarioustypesofpriority,andthenperformcorrespondingcalculations.byteshortcharintlongfloatdoubleTotalpriceofpears：6*3=18(元)