Java 자바 UNIX Timestamp 변환 timestamp to date String

public String getTimestampToDate(String timestampStr){
    long timestamp = Long.parseLong(timestampStr);
    Date date = new java.util.Date(timestamp*1000L); 
    SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
    sdf.setTimeZone(java.util.TimeZone.getTimeZone("GMT+9")); 
    String formattedDate = sdf.format(date);
    return formattedDate;
}

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