Java tutorial
//package com.java2s; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Locale; public class Main { public static String getCurrentMonthFirstDay(long time) { DateFormat dateFormat = new SimpleDateFormat("yyyy-MM", Locale.CHINA); StringBuilder stringBuilder = new StringBuilder(); stringBuilder.append(dateFormat.format(time)); stringBuilder.append("-"); stringBuilder.append(1); return stringBuilder.toString(); } }