写日志到文件
public static boolean print(String filepath,String text){
 
 File file = new File(filepath);
 FileWriter fw = new FileWriter(file,true);
 BufferWriter bw =new BufferWriter(fw);
 
 PrintWriter pw = new PrintWriter(bw);
 
 pw.println(getDate()+":"+text); pw.close();
 bw.close();
 fw.close();
 return true;
}递归实现阶乘算法
public static int factorial(int n){
 if(n==1){
  return 1;
 }
 return n*factorial(n-1);
}按当地市区打印当前日期
Date date = new Date();
System.out.println(date.toLocaleString());
输出：3013-5-23将毫秒转化成日期
long now= System.currentTimeMills();
Date date =new Date(now);
System.out.println(date);java时间格式化处理
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy MM dd HH mm ss");
System.out.println(sdf.format(date));