請問如何得到上一個月的最後一天呢？

小鱼儿 2022-04-17 01:25 43阅读 0赞

public static  String ss(){
       
    		Calendar   cal=Calendar.getInstance();//当前日期
    		cal.set(Calendar.DATE,1);//设为当前月的1号
    		cal.add(Calendar.DATE,-1);//减一天，变为上月最后一天
    		SimpleDateFormat   simpleDateFormat   =   new   SimpleDateFormat( "yyyy-MM-dd ");
    		return simpleDateFormat.format(cal.getTime());//输出2005-04-30
    
    
    	}

package com.java.page;
    
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.regex.Matcher;
    import java.util.regex.Pattern;
    
    public class Test {
       
    	public static void main(String[] args) {
       
    
    			Calendar   cal=Calendar.getInstance();//当前日期
    		//	cal.set(Calendar.DATE,1);//设为当前月的1号
    		//	cal.add(Calendar.DATE,-1);//减一天，变为上月最后一天
    			System.out.println("现在的时间是："+Calendar.MONTH);
    			int n=5;
    			String[] str = {"1月31号","2月29号","3月31号","4月30号","5月31号","6月30号","7月31号","8月31号","9月30号","10月31号","11月30号","12月31号"};
    			for(int i=0;i<12;i++){
       
    				if((cal.get(Calendar.MONTH)+1)==i){
       
    						System.out.println(str[i-1]);
    				}
    
    			}
    			if(Calendar.MONTH==5){
       
    
    				cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
    				SimpleDateFormat   simpleDateFormat   =   new   SimpleDateFormat( "yyyy-MM-dd ");
    				simpleDateFormat.format(cal.getTime());//输出2005-04-30
    
    				System.out.println("现在的时间是："+simpleDateFormat.format(cal.getTime()));
    			}
    
    	}
    
    }

package com.java.page;
    
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    import java.util.Date;
    import java.util.GregorianCalendar;
    
    
    public class Student {
       
    
    	public  static void main(String args[])throws Exception{
       
    	//	Calendar cal=Calendar.getInstance();
    	//	cal.set(Calendar.MONTH, 6);
    	//	cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
    	//	System.out.println(cal.getTime());
    		System.out.println(getLastDay());
    		System.out.println(getLastDayOfLastMonth());
    		System.out.println("---------"+ss());
    		System.out.println("=========="+sd());
    
    	}
    	public static String getLastDay(){
       
    
    		SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
    		  Calendar calendar = Calendar.getInstance();//此时打印它获取的是系统当前时间
    		        calendar.add(Calendar.DATE, -1); //
    		        Date theDate = calendar.getTime();
    		        String s = df.format(theDate);
    		        System.out.println(s);
    
    		      return s;
    
    		}
    	public static Date getLastDayOfLastMonth() {
       
    		Calendar calendar = new GregorianCalendar();
    		calendar.set(Calendar.DATE, 1);
    		calendar.set(Calendar.HOUR, 0);
    		calendar.set(Calendar.MINUTE, 0);
    		calendar.set(Calendar.SECOND, 0);
    		calendar.set(Calendar.MILLISECOND, 0);
    		long mils = calendar.getTime().getTime();
    		mils -= 24 * 60 * 60 * 1000;
    		return new Date(mils);
    		}
    	public static  String ss(){
       
    		Calendar   cal=Calendar.getInstance();//当前日期
    		cal.set(Calendar.DATE,1);//设为当前月的1号
    		cal.add(Calendar.DATE,-1);//减一天，变为上月最后一天
    		SimpleDateFormat   simpleDateFormat   =   new   SimpleDateFormat( "yyyy-MM-dd ");
    		return simpleDateFormat.format(cal.getTime());//输出2005-04-30
    
    
    	}
    	public static String sd(){
       
    		//Calendar   cal=Calendar.getInstance();
    		Calendar   cal=new   GregorianCalendar(2000,2,1);
    		cal.add(Calendar.MONTH,-1);
    		return "2000年3月1号的上个月份最后一天是 "+cal.getActualMaximum(Calendar.DAY_OF_MONTH);
    
    	}
    
    
    }

package com.java.page;
    
    import java.text.SimpleDateFormat;
    import java.util.Calendar;
    
    public class Hello {
       
    	public static void main(String args[]){
       
    		Calendar cal=Calendar.getInstance();
    		System.out.println(cal.get(Calendar.YEAR)+"年");
    		System.out.println(cal.get(Calendar.MONTH)+1+"月");
    		System.out.println(cal.get(Calendar.DATE)+"日");
    		System.out.println("<br/>");
    		java.util.Date date=new java.util.Date();
    		SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM");
    		String nowm=sdf.format(date);
    		System.out.println("现在的时间是："+nowm);
    	}
    
    }