一个菜鸟的简单有关问题.

一个初学者的简单问题....
import   java.io.*;
public   class   Deposit{
static   int   balance   =   1000;
public   static   void   main(String[]   ages){
PrintWriter   out   =   new   PrintWriter(System.out,true);
Account   account=new   Account(out);
DepositThread   first,second;
first=new   DepositThread(account,1000, "#1 ");
second=new   DepositThread(account,1000, "\t\t\t\t#2 ");
first.start();
second.start();
try{
first.join();
second.join();
}
catch(InterruptedException   e){}
out.println( "***Final   balance   is "+balance);
}
}


class   Account{
PrintWriter   out;
Account(PrintWriter   out){
this.out=out;
}
void   deposit(int   amount,String   name){
int   balance;
out.println(name+ "trying   to   deposit "+amount);
out.println(name+ "getting   balance... ");
balance   =   getBalance();
out.println(name+ "balance   got   is "+balance);
balance+=amount;
out.println(name+ "setting   balance... ");
setBalance(balance);
out.println(name+ "new   balanace   set   to "+Deposit.balance);
}
int   getBalance(){
try{
Thread.sleep(5000);
}
catch(InterruptedException   e){}
return   Deposit.balance;
}
void   setBalance(int   balance){
try{
Thread.sleep(5000);
}
catch(InterruptedException   e){}
Deposit.balance=balance;
}
}

class   DepositThread   extends   Thread{
Account   account;
int   depositAmount;
String   message;
DepositThread(Account   account,int   amount,String   message){
this.message   =   message;
this.account=account;
this.depositAmount=amount;
}
public   void   run(){
account.deposit(depositAmount,message);
}
}

在上面的程序中..为什么要用PrintWriter   out=new   PrintWriter(System.out,true)这样一句呐?它的作用是什么啊?
谢谢..

------解决方案--------------------
就是对 System.out 封装一下

不过在你的程序中应该是多此一举

因为只是简单的输出一个数字


------解决方案--------------------
PrintWriter
public PrintWriter(OutputStream out)根据现有的 OutputStream 创建不带自动行刷新的新 PrintWriter。此便捷构造方法创建必要的中间 OutputStreamWriter，后者使用默认字符编码将字符转换为字节。

参数：
out - 输出流
另请参见：
OutputStreamWriter.OutputStreamWriter(java.io.OutputStream)

--------------------------------------------
自己查一下JavaDoc就知道了
http://gceclub.sun.com.cn/Java_Docs/html/zh_CN/api/index.html