Dab tsi yog cov npe sib txawv hauv Java?

2024 Tus sau: Lynn Donovan | [email protected]. Kawg hloov kho: 2023-12-15 23:47

Tag nrho cov npe sib txawv yuav tsum pib nrog ib tsab ntawv ntawm cov tsiaj ntawv, ib tug underscore, los yog (_), los yog ib tug duas kos npe ($). Lub rooj sib txoos yog ib txwm siv ib tsab ntawv ntawm cov tsiaj ntawv. Cov kos npe duas thiab cov underscore poob siab. Tom qab thawj tsab ntawv pib, cov npe sib txawv kuj tseem muaj cov tsiaj ntawv thiab tus lej 0 txog 9.

Tom qab ntawd, cov npe sib txawv yog dab tsi?

A valid variable npe pib nrog ib tsab ntawv thiab tsis muaj ntau tshaj namelengthmax cov cim . Siv tau cov npe sib txawv tuaj yeem suav nrog cov tsiaj ntawv, lej, thiab underscores.

Tom qab, lo lus nug yog, dab tsi yog cov npe sib txawv raws cai hauv Java? Dab tsi yog cov npe sib txawv raws cai hauv java. Cov npe sib txawv yog qhov tseem ceeb. Lub npe hloov pauv tuaj yeem yog tus lej raws cai - cov ntawv tsis txwv-ntev thiab tus lej, pib nrog tsab ntawv, tus lej kos npe "$", lossis tus lej hauv qab tus cwj pwm ““.

Ntxiv mus, dab tsi Tsis tuaj yeem siv rau lub npe sib txawv hauv Java?

Keywords yog predefined, reserved lus siv hauv Java programming uas muaj lub ntsiab lus tshwj xeeb rau lub compiler. Koj ua tsis tau siv cov ntsiab lus xws li int, rau, chav kawm thiab lwm yam variable npe (los yog tus cim) raws li lawv yog ib feem ntawm Java programming lus syntax.

Dab tsi yog cov npe hloov pauv tsis raug?

Cov hauv qab no yog cov piv txwv ntawm cov npe hloov pauv tau : age, gender, x25, age_of_hh_head. Cov hauv qab no yog cov piv txwv ntawm invalid variable npe : age_ (xaus nrog ib qho underscore);

Lub npe sib txawv yog ib lo lus uas tsuas muaj cov hauv qab no:

• Lus Askiv A.. Z thiab a.. z;
• Cov lej 0..
• ib tug underscore cim "_".