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Sql Date与Date
java.sql.Date 是针对SQL语句使用的，它只包含日期而没有时间部分;java.util.Date 是 java.sql.Date 的父类（注意拼写）前者是常用的表示时间的类，我们通常格式化或者得到当前时间都是用他.后者之后在读写数据库的时候用他，因为PreparedStament的setDate()的第2参数和ResultSet的getDate()方法的第2个参数都是java.sql.Date
java.sql.Date date=new java.sql.Date();
java.util.Date d=new java.util.Date (date.getTime());
另:
java.sql.Time sTime=new java.sql.Time(d.getTime());
java.sql.Timestamp stp=new java.sql.Timestamp(d.getTime());
Java访问Oracle，设置动态SQL参数值Number类型的小数可用setString(), setBigDecimal()来设置. 用setFloat()会发生舍入误差.例如:9999999999.99 会变成10000000000.
Java连接Oracle
Connection conn = new OracleDriver().defaultConnection();
String sql = "INSERT INTO user (id,name) " + "VALUES (?,?)";
try {
      PreparedStatement pstmt = conn.prepareStatement(sql);
      pstmt.setString(1, id);
      pstmt.setString(2, name);
      pstmt.executeUpdate();
      pstmt.close();
    } catch (SQLException e) { }
How to get current date string like '11-MAY-2006'
      Locale aLocale = new Locale("en");
      Calendar cal = new GregorianCalendar();
      Date date = cal.getTime();
      SimpleDateFormat sf = new SimpleDateFormat("dd-MMM-yyyy", aLocale);
      System.out.println("==============curdate="+sf.format(date));
How to get the next day of a specified date?
import java.util.GregorianCalendar;
GregorianCalendar cal = new GregorianCalendar (2005, 8, 1, 0, 0,1);
cal.add(GregorianCalendar.DAY_OF_MONTH, 1);
Date nextday = cal.getTime();
-Please note that, the value used to set the MONTH time field in the calendar is 0-based. e.g., 0 for January.
How to copy files

import java.io.*;
public class Copy ...{
  public static void main(String[] args) throws IOException ...{
    File inputFile = new File("farrago.txt");
    File outputFile = new File("outagain.txt");
    FileReader in = new FileReader(inputFile);
    FileWriter out = new FileWriter(outputFile);
    int c;
    while ((c = in.read()) != -1)
      out.write(c);
    in.close();
    out.close();
  }
}
How to use Properties

Properties prop = new Properties();
prop.setProperty("abc", "");
Please note that, NullPointerException will be thrown: prop.setProperty("abc", null);
How to remove all '-' in the string

System.out.println("str="+str.replaceAll("-", ""));
How to trim a string

String abc = " 300.00";
System.out.println("trim="+abc.trim());
How to use StringTokenizer?

String str = "'001','182-0-935722','',' 0.00',' 0.00','','20 Jul 2006','2','6','1820935722',''";
StringTokenizer st = new StringTokenizer(str.substring(str.indexOf("(")+1, str.indexOf(")")), ",");
String[] strArray = new String[11];
System.out.println(st.countTokens());
while (st.hasMoreElements())...{
     String next = st.nextToken();
     System.out.println("next="+next);
      //remove ' '
     System.out.println("next="+next.substring(1, next.lastIndexOf("'")));
}