打印输出昨日的当前时间

package ForeverLover;import java.text.SimpleDateFormat;import java.util.Calendar;public class DateSystem {	/**	 * @author ForeverLover	 */	public static void main(String[] args) {				SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");		Calendar cal = Calendar.getInstance();		cal.add(Calendar.DATE, -1);		System.out.println(sdf.format(cal.getTime()));			}}