获取每月第一天最后一天 java

        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");   

        //获取前月的第一天  
        Calendar   cal_1=Calendar.getInstance();//获取当前日期   
        cal_1.add(Calendar.MONTH, -1);  
        cal_1.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天   
        firstDay = format.format(cal_1.getTime());  
        System.out.println("-----1------firstDay:"+firstDay);  
        //获取前月的最后一天  
        Calendar cale = Calendar.getInstance();     
        cale.set(Calendar.DAY_OF_MONTH,0);//设置为1号,当前日期既为本月第一天   
        lastDay = format.format(cale.getTime());  
        System.out.println("-----2------lastDay:"+lastDay);  
          
          
        //获取当前月第一天：  
        Calendar c = Calendar.getInstance();      
        c.add(Calendar.MONTH, 0);  
        c.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天   
        String first = format.format(c.getTime());  
        System.out.println("===============first:"+first);  
          
        //获取当前月最后一天  
        Calendar ca = Calendar.getInstance();      
        ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));    
        String last = format.format(ca.getTime());  
        System.out.println("===============last:"+last);