Shirye-shirye: Java. bayanai iri

A data type ne m da uku aka gyara:

• kafa na dabi'u ko abubuwa.
• wani sa na ayyukan da cewa ana iya amfani da duk dabi'u a cikin sa.
• gabatar da bayanai, tabbatas da ajiya.

Mene ne daban-daban data iri a Java?

Da shirye-shirye da harshen ƙunshi wasu tsararrun gina-in-daban, da kuma damar shirye-shirye domin ayyana nasu al'ada.

A Java bayanai iri kasu kashi m da kuma tunani.

"Kayan" yana nufin cewa wani m division ne ba zai yiwu ba. Expand ko ba da damar ya canza ta da shirye-shirye da harshen. Irin wannan m data type bayyana da kuma sauran iri mai amfani.

A m of m irin ƙunshi daraja da kuma tunani - adireshin da abu a ƙwaƙwalwar ajiyar.

A Java harshe. Data iri: lokaci da kuma kwanan wata

Hadedde data kasu kashi azuzuwan, musaya, da kuma iri-iri. A membobin wani dubawa irin ne m hanyoyin da constants. A Java bayanai iri kwanan wata da lokaci ana kafa constructor Kwanan wata ():

• d = sabon Kwanan wata ().

Wani misali na reference matsayin kirtani.

A Java harshe. Data Nau'in: Kirtani

A kirtani ne a aji a tsare a cikin Java library, kuma shi za a iya amfani da kalmar aiki (jerin haruffa).

Ads reference Kirtani-m kamar haka: Kirtani str.

Kafin ka sanya wani abu tunani irin wannan m, dole ne ka halitta shi ta amfani da sabon sadarwarka. Alal misali, za ka iya ƙirƙirar Kirtani abu da rubutu "Hello":

• str = sabon Kirtani ( "Hello").

Abin da ya faru a lokacin da ka gudu wannan code? Da farko, ƙwaƙwalwar ajiya da aka kasaftawa, kuma da sunan str hade da wannan memory cell. Wannan shi ne wani daban-daban daga furta mai m m. Na biyu yanki na code halitta da Kirtani abu a ƙwaƙwalwar ajiyar da rubutu "Hello" da kuma Stores wani tunani shi (ko ƙwaƙwalwar adireshin) a cikin str.

Reference Java bayanai iri ma da damar sanya wani tunani don wani abu da aka adana a wani m wasu. Su duka biyu koma zuwa wannan abu a cikin ƙwaƙwalwar ajiyar. Wannan za a iya samun kamar haka:

• Kirtani str1.
• Kirtani str2.
• str1 = sabon Kirtani ( "Hello");
• str2 = str1.

Akwai m reference null, wanda za a iya sanya masa wani takwara reference m. Yana ba koma zuwa wannan abu.

Kirtani abu da aka halitta ta amfani da sabon sadarwarka. Amma kamar yadda na kirtani ana amfani da sau da yawa, akwai wani sauki hanyar haifar da shi. All kirtani literals, t. E. A jerin haruffa a kewaye a cikin biyu zance alamomi suna bi a matsayin abubuwa Kirtani. Saboda haka, maimakon sabon sadarwarka, za ka iya amfani da kirtani literals:

• Kirtani str1 = "Hello".

M Java bayanai iri - byte, short, int, tsawo, char, taso kan ruwa, biyu, da kuma Boolean. Sun kasu kashi biyu Categories: ma'ana da kuma na lamba. A karshen za a iya raba cikin lamba da kuma iyo batu.

Entire Java data iri ne Tazarar iri wanda dabi'u ne integers. Biyar daga cikinsu: byte, short, int, tsawo, da kuma char.

Int

Int ne 32-bit alamar m data type. M yana amfani da 32 ragowa da ƙwaƙwalwar ajiyar. The yarda kewayon - -2147483648 da 2147483647 (-2 ³¹ zuwa 2 ³¹ - 1). All integers a cikin wannan fanni ne lamba literals ko constants. Alal misali, 10, -200, 0, 30, 19 ne literals int. Su za a iya sanya wani m int:

• int num1 = 21;

Lamba literals za a iya bayyana a binary, octal, gidan goma da hexadecimal lambobin.

Lokacin da na zahiri yana farawa a sifili, kuma yana da akalla biyu lambobi, an dauke da za a rubuta a octal. 0 kuma 00 wakiltar guda darajar - sifili.

All literals int format hexadecimal lambobin fara da 0x ko 0x, kuma dole ne su dauke da akalla daya hexadecimal lambobi:

• int num1 = 0x123.

Int-literals a cikin format na wani binary lambar farawa da 0b ko 0B:

• int num1 = 0b10101.

Long

Yana da wani 64-bit hannu m irin. Yana amfani a lokacin da sakamakon da lissafi iya wuce zangon int. Range dogon - -2 ⁶³ zuwa 2 ⁶³ - 1. Duk integers cewa Range literals ne dogon irin.

Don rarrabe Java harshen bayanai iri int da tsawo, na zahiri da karshen irin yaushe ƙare L ko l.

Lamba Literals dogon irin ƙila za a bayyana, a octal, hexadecimal, kuma binary Formats.

Lokacin da dogon-zahiri da aka sanya wa wani m tsawo, Java tarawa jami'in dake duba yawan sanya darajar da kuma tabbatar da cewa shi ne a cikin m range. in ba haka ba, wani tari kuskure zai faru.

Tun int iyaka ne karami fiye da dogon, int-m darajar iya ko da yaushe a sanya wani m na irin dogon. Amma da reappropriation ne ba zai yiwu ba har ma a cikin kewayon int. A saboda wannan dalili, nuna qarara:

• num1 = (int) num2.

byte

Byte ne 8-bit da wani m irin. Its kewayon - 127 zuwa -128 (-2 ⁷ 2 ⁷ - 1). Wannan shi ne mafi karami lamba type, akwai a Java. Yawanci, byte canji an yi amfani da lokacin da shirin hannu da yawa na dabi'u a cikin kewayon -128 zuwa 127, ko a lõkacin da aiki tare da binary data. Ba kamar na zahiri da int, tsawo, byte-literals sun bata. Duk da haka, za ka iya sanya wani m byte-int-zahiri, tun da ya rufe zangon bytes.

Idan m ne daga fuska, Java tarawa zai samar da wani kuskure.

Bugu da kari, za ka iya sanya kawai int-zahiri, amma ba da darajar adana a cikin m int, kamar yadda wannan na iya rasa daidaito. Wannan na bukatar da bayyane irin.

• B1 = (byte) num1.

short

Yana da wani 16-bit hannu lamba data irin m. Its kewayon - daga -32768 zuwa 32767 (ko -2 ¹⁵ zuwa 2 ¹⁵ - 1).

Kamar yadda wani janar mulki, da bukatar takaice m faruwa a lokacin da shirin yana amfani da wani babban yawan dabi'u cewa kada ku ƙẽtare kayyade range. Short-zahiri ya bace, amma da ikon sanya wani zahiri int cikin kewayon takaice. Byte-darajar da m za a iya sanya sau. Sauran dokoki sanya wani int ko wani dogon short-m ne guda a matsayin mai byte.

Char

Char ne Unsigned 16-bit m data type cewa wakiltar da Unicode hali. Babu alamar na nuni da cewa m ba zai iya zama korau. Range - daga 0 zuwa 65.535, wanda ya yi daidai da tsarinsa Unicode haruffa. A zahiri ne char darajar da za a iya bayyana a cikin wadannan siffofin:

• harafin kewaye a cikin guda quotes.
• jerin iko alamomin.
• jerin Unicode iko haruffa;
• jerin octal iko haruffa.

Alama ce mai yiwuwa a bayyana ta kwasfa da shi a cikin guda quotes: char C1 = 'A'. Biyu zance da alãmarsu nuna wani layi na zahiri da cewa ba za a iya sanya wa char-m, ko da kirtani ne kawai daya hali. Wannan shi ne unacceptable, saboda mahada ba m m da ake sa. All kirtani literals ne batun Class Kirtani da haka nufin alhãli kuwa hali ne da ake m irin.

Zahiri bayyana jerin iko, an rubuta kamar yadda na backslash alama a guda quotes. A total na 8: '\ n ",' \ r ',' \ f ',' \ b ',' \ t ',' \\ ',' \" ',' \ ''.

A lura da Unicode jerin ne '\ uxxxx', inda \ u (backslash bi ta Ƙaramin baki u) suturta ta farko, XXXX wakiltar daidai hudu hexadecimal lambobi a cikin Unicode hali code tsarin. Alal misali, 'A' an saita zuwa 65 a cikin gidan goma tsarin da kuma 41 a hexadecimal. Saboda haka, wannan alama ce da za a iya wakilta a matsayin '\ u0041'.

Octal gudun hijira jerin aka rubuta a matsayin '\ NNN', inda n - octal lambobi (0-7). Darajar kewayon - daga '\ 000' ga '\ 377', wanda yayi dace ₈ 377 255 _10. Saboda haka, yana da ake amfani da su wakilci haruffa da code daga 0 zuwa 255, da ake bukata domin interoperability tare da sauran shirye-shirye harsuna. Ba kamar Unicode jerin, inda ya cancanta, duk hudu hexadecimal lambobi, za ka iya amfani da 1, 2 ko 3 octal: '\ n ",' \ nn 'ko' \ NNN '.

Boolean

Boolean yana da kawai biyu real dabi'u: gaskiya (gaskiya), da ƙarya (ƙarya). Suna da ake kira Boolean literals. A ma'ana m ba za a iya bai wa wani irin, da kuma mataimakin versa. Java ba ayyana Boolean size - shi ya dogara da takamaiman aiwatar rumfa Java- inji.

Java bayanai iri iyo batu

A lambar cewa ya ƙunshi wani fractional part, za a iya adana a cikin misali da tsayayyen adadin lambobi kafin da kuma bayan da gidan goma aya ko wani nuni da matsayinta a cikin kwamfuta ta ƙwaƙwalwar. Tun da yawan lambobi iya bambanta, aka ce cewa batu "gudãna".

A Java harshe iri iyo-aya data yin amfani da 32 ragowa. Bisa ga IEEE 754 misali, wannan yayi dace da guda ainihin wanda damar wakilci, misali, na 1.4 x 10 ^-45 da kuma 3.4 x 10 ^38, a cikinsa biyu tabbatacce kuma korau.

All real lambobin cewa ƙare a cikin f ko F, kira taso kan ruwa-literals. Su za a iya wakilta a gidan goma lambar a cikin nau'i na kimiyya tsarin rubutu. Ga misali:

• taso kan ruwa F1 = 3.25F.
• taso kan ruwa F2 = 32.5E-1F.
• taso kan ruwa f3 = 0.325E + 1F.

Type ma'anar biyu zeros: + 0.0F (ko 0.0F) da kuma -0.0F. Duk da haka, don kwatanta, duka biyu dauke daidaita sifili raga. Bugu da kari, sun gano iri biyu rashin iyaka: tabbatacce kuma korau. A sakamakon wasu ayyukan (msl, division to 0.0F 0.0F) ba gano da kuma gabatar musamman da darajar nan.

biyu daidaici

Domin ajiya na iyo ma'ana biyu yana amfani da 64 ragowa. Yawan biyu daidaici na iya zama duka kyau da kuma mummunan dabi'u na girma na 4.9 ^-324 x 10 da kuma 1.7 x ^10.308.

All real lambobi ne da tsoho biyu literals. Optionally iya baro-baro nuna a fakaice kari na baya baki d, ko D, msl, 19.27d. Biyu na zahiri iya bayyana a gidan goma tsari da kuma a kimiyya tsarin rubutu.