▁The ▁programmer ▁was ▁given ▁the ▁bur den ▁of ▁being ▁aware ▁of ▁dangerous ▁issues ▁such ▁as ▁un initial ized ▁variables . ▁ ▁In ▁other ▁languages , ▁variables ▁are ▁often ▁initialized ▁to ▁known ▁values ▁when ▁created . ▁ ▁Ex amples ▁include : ▁ ▁V H DL ▁initial izes ▁all ▁standard ▁variables ▁into ▁special ▁' U ' ▁value . ▁It ▁is ▁used ▁in ▁simulation , ▁for ▁debugging , ▁to ▁let ▁the ▁user ▁to ▁know ▁when ▁the ▁don ' t ▁care ▁initial ▁values , ▁through ▁the ▁mult ival ued ▁logic , ▁affect ▁the ▁output . ▁ ▁Java ▁does ▁not ▁have ▁un initial ized ▁variables . ▁Field s ▁of ▁classes ▁and ▁objects ▁that ▁do ▁not ▁have ▁an ▁explicit ▁initial izer ▁and ▁elements ▁of ▁arrays ▁are ▁automatically ▁initialized ▁with ▁the ▁default ▁value ▁for ▁their ▁type ▁( false ▁for ▁boolean , ▁ 0 ▁for ▁all ▁numerical ▁types , ▁null ▁for ▁all ▁reference ▁types ). ▁Local ▁variables ▁in ▁Java ▁must ▁be ▁definitely ▁assigned ▁to ▁before ▁they ▁are ▁accessed , ▁or ▁it ▁is ▁a ▁compile ▁error . ▁Python ▁initial izes ▁local ▁variables ▁to ▁NULL ▁( dist inct ▁from ▁None ) ▁and ▁ra ises ▁an ▁Un bound Local Error ▁when ▁such ▁a ▁variable ▁is ▁accessed ▁before ▁being ▁( re ) initial ized ▁to ▁a ▁valid ▁value . ▁D ▁initial izes ▁all ▁variables ▁unless ▁explicitly ▁specified ▁by ▁the ▁programmer ▁not ▁to . ▁ ▁Even ▁in ▁languages ▁where ▁un initial ized ▁variables ▁are ▁allowed , ▁many ▁comp ilers ▁will ▁attempt ▁to ▁identify ▁un initial ized ▁variables ▁and ▁report ▁them ▁as ▁compile - time ▁errors .