Thread Example
public class Account {
private String accountNo;
private double balance;
public Account(){}
public Account(String accountNo,double balance){
this.accountNo = accountNo;
this.balance = balance;
}
public double getBalance(){
return this.balance;
}
public void draw(double drawAmount){
if(balance >= drawAmount){
System.out.println(Thread.currentThread().getName()+ " " +drawAmount);
balance -= drawAmount;
System.out.println("leftmoney is "+balance);
}else{
System.out.println(Thread.currentThread().getName()+ " failed");
}
}
public inthashCode(){
return accountNo.hashCode();
}
public boolean equals(Object obj){
if(obj==this){
return true;
}
if(obj!=null&obj.getClass()==Account.class){
Accounttarget = (Account)obj;
return target.accountNo.equals(accountNo);
}
return false;
}
}
class DrawThread1 extends Thread{
private Account account;
private double drawAmount;
public DrawThread1(String name,Account account,double drawAmount){
super(name);
this.account = account;
this.drawAmount = drawAmount;
}
public void run(){
account.draw(drawAmount);
}
}
public class DrawThread{
public static void main(String[] args){
Account acct = new Account("1234567",1000);
new DrawThread1("1",acct,800).start();
new DrawThread1("2",acct,800).start();
}
}
Output:
1800.0
leftmoney is 200.0
2800.0
left money is -600.0
public class DrawThread{
public static void main(String[] args) throws InterruptedException{
Account acct = new Account("1234567",1000);
new DrawThread1("1",acct,800).start();
Thread.sleep(100);
new DrawThread1("2",acct,800).start();
}
}
Output:
1800.0
leftmoney is 200.0
2 failed
为了让Account能更好地使用多线程环境，可以将Account类修改为线程安全的方式，线程安全的类具有如下特征：
该类的对象可以被多个线程安全地访问；
每个线程调用该对象的任意方法之后都将得到正确结果；
每个线程调用该对象的任意方法之后，该对象状态依然保持合理状态。
public synchronized double getBalance(){
return this.balance;
}
public synchronized void draw(double drawAmount){
if(balance >= drawAmount){
System.out.println(Thread.currentThread().getName()+ " " +drawAmount);
balance -= drawAmount;
System.out.println("leftmoney is "+balance);
}else{
System.out.println(Thread.currentThread().getName()+ " failed");
}