我经历了一本书,看到说,下面代码的代码是线程同步:同步在java中给人意想不到的输出
// Account类
public class Account {
private double balance;
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
public synchronized void addAmount(double amount) {
double tmp=balance;
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
tmp+=amount;
balance=tmp;
}
public synchronized void subtractAmount(double amount) {
double tmp=balance;
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
tmp-=amount;
balance=tmp;
}
}
//银行类
public class Bank implements Runnable {
private Account account;
public Bank(Account account) {
this.account=account;
}
@Override
public void run() {
for (int i=0; i<1000; i++){
account.subtractAmount(1000);
}
}
}
//公司类
public class Company implements Runnable {
private Account account;
public Company(Account account) {
this.account=account;
}
@Override
public void run() {
for (int i=0; i<1000; i++){
account.addAmount(1000);
}
}
}
//主类
public class Main {
public static void main(String[] args) {
Account account=new Account();
account.setBalance(1000);
Company company=new Company(account);
Thread companyThread=new Thread(company);
Bank bank=new Bank(account);
Thread bankThread=new Thread(bank);
System.out.printf("Account : Initial Balance: %f\n",account.
getBalance());
companyThread.start();
bankThread.start();
try {
companyThread.join();
bankThread.join();
System.out.printf("Account : Final Balance: %f\n",account.
getBalance());
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
}
两个不同的对象的这里有两个线程正在发生变化,在使用addAmount和subtractAmount功能的同时平衡的变量,但它总是给人右输出作为声母韵母平衡相同即1000.000。我的意思是他们应该是我的一些问题,因为这两个线程同时在同一个变量上工作。
请纠正我在哪里错了。 预先感谢
这就是为什么你使用'同步' – QBrute
其实,这本书是不完全正确的。您可以设置天平不同步。只有加和减是。你能告诉我们它是什么书吗? – Fildor