获取当前月份的第一天和最后一天，上个月的第一天和最后一天

上个月第一天和最后一天
 

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class TestController {
    public static void main(String[] args) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        //获取当前月的第一天
        Calendar c = Calendar.getInstance();
        c.add(Calendar.MONTH,-1);
        c.set(Calendar.DAY_OF_MONTH,1);
        String dataStart = df.format(c.getTime());
        //获取当月最后一天
        Calendar c1 = Calendar.getInstance();
        c1.add(Calendar.MONTH,-1);
        c1.set(Calendar.DAY_OF_MONTH, c1.getActualMaximum(Calendar.DAY_OF_MONTH));
        String dataEnd = df.format(c1.getTime());
    }
}

当月第一天和最后一天：
 

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class TestController {
    public static void main(String[] args) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        //获取当前月的第一天
        Calendar c = Calendar.getInstance();
        c.set(Calendar.DAY_OF_MONTH,1);
        String dataStart = df.format(c.getTime());
        //获取当月最后一天
        Calendar c1 = Calendar.getInstance();
        c1.set(Calendar.DAY_OF_MONTH, c1.getActualMaximum(Calendar.DAY_OF_MONTH));
        String dataEnd = df.format(c1.getTime());
    }
}