求给我讲解下红色部分的代码
import java.util.Calendar;
import java.util.GregorianCalendar;
public class DateTime {
private Calendar calendar = new GregorianCalendar();
public String getDate() {
StringBuffer buf = new StringBuffer();
buf.append(calendar.get(Calendar.YEAR)).append("-");
buf.append(this.addZero(calendar.get(Calendar.MONTH) + 1, 2)).append(
"-");
buf.append(this.addZero(calendar.get(Calendar.DAY_OF_MONTH), 2))
.append(" ");
buf.append(this.addZero(calendar.get(Calendar.HOUR_OF_DAY), 2)).append(
":");
buf.append(this.addZero(calendar.get(Calendar.MINUTE), 2)).append(".");
buf.append(this.addZero(calendar.get(Calendar.MILLISECOND), 3));
return buf.toString();
}
private String addZero(int temp, int len) //在某些位不足的情况下加上“0”
{
StringBuffer str = new StringBuffer();
str.append(temp); // 加入数字
while (str.length() < len) {
str.insert(0, 0);
}
return str.toString();
}
public static void main(String[] args) {
System.out.println(new DateTime().getDate());
}
}
输出的结果格式类似于“2013-01-28 21:02.078” 我想求教给我讲下红色代码处的内存活动情况,或者讲讲这段代码,初学java不是很理解 拜托了 みなさん