DouKaku?

// 準備
def mappingTable = [
    [range:18680908..19120730,gengo:"明治"]
    ,[range:19120730..19261225,gengo:"大正"]
    ,[range:19261225..19890108,gengo:"昭和"]
    ,[range:19890108..99991231,gengo:"平成"]
]

try{
    // 本処理開始
    def input = args[0]
    if(!input) throw new IllegalArgumentException()
    def columns = input.split("/")
    if(columns?.size() != 3) throw new IllegalArgumentException()

    def year = columns[0].toInteger()
    def month = columns[1].toInteger()
    def date = columns[2].toInteger()

    // 日付チェック
    Calendar cal = Calendar.getInstance()
    cal.setLenient( false )
    cal.set(year, month-1, date)
    cal.getTime()

    def value = columns.join("").toInteger()
    def matchs = mappingTable.findAll{ value in it.range }
    if( matchs.empty ){
        throw new IllegalArgumentException()
    }
    
    matchs.each{
        if( value in it.range ){
            def wayear = year - (int)(it.range[0]/10000) + 1
            println "${it.gengo}${wayear}年${month}月${date}日"
        }
    }
} catch (IllegalArgumentException e){
    println "範囲外"
}