Get the first and last days of the current month, and the first and last days of the previous month

The first and last day of last month
 

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

public class TestController {
    public static void main(String[] args) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        // Get the first day of the current month 
        Calendar c = Calendar.getInstance();
        c.add(Calendar.MONTH,-1);
        c.set(Calendar.DAY_OF_MONTH,1);
        String dataStart = df.format(c.getTime());
        // Get the last day of the month 
        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());
    }
}

First and last day of the month ：
 

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

public class TestController {
    public static void main(String[] args) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        // Get the first day of the current month 
        Calendar c = Calendar.getInstance();
        c.set(Calendar.DAY_OF_MONTH,1);
        String dataStart = df.format(c.getTime());
        // Get the last day of the month 
        Calendar c1 = Calendar.getInstance();
        c1.set(Calendar.DAY_OF_MONTH, c1.getActualMaximum(Calendar.DAY_OF_MONTH));
        String dataEnd = df.format(c1.getTime());
    }
}