package thread;
public class ThreadTest1 {
public static void main(String[] args) {
//创建一个公用的账户
Account act = new Account("zhangsan",5000.0);
Thread t1 = new Thread(new PrimeRun(act));
Thread t2 = new Thread(new PrimeRun(act));
//设置线程的名字
t1.setName("t1");
t2.setName("t2");
t1.start();
t2.start();
}
}
//创建取款线程
class PrimeRun implements Runnable{
Account act ;
PrimeRun(Account act){
this.act = act;
}
public void run() {
try {
act.withDraw(1000.0);
System.out.println(Thread.currentThread().getName()+ "取款1000.0成功，所剩余额：" + act.getBalance());
} catch (Exception e) {
e.printStackTrace();
}
}
}
//账户
class Account{
private String actno;
private double balance;
Account(){};
//给账户赋初始值
Account(String actno,double balance){
this.actno = actno;
this.balance = balance;
}
//取款余额
public void withDraw(double money){
double after = balance - money;
try {
Thread.sleep(2000); //为达到预期效果，此处线程休眠2秒
} catch (Exception e) {
e.printStackTrace();
}
this.balance = after;
}
public String getActno() {
return actno;
}
public void setActno(String actno) {
this.actno = actno;
}
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
}
我们看看输出结果：
t2取款1000.0成功，所剩余额：4000.0
t1取款1000.0成功，所剩余额：4000.0
结果很明显不符合要求：代码重新修改如下：
package thread;
public class ThreadTest1 {
public static void main(String[] args) {
//创建一个公用的账户
Account act = new Account("zhangsan",5000.0);
Thread t1 = new Thread(new PrimeRun(act));
Thread t2 = new Thread(new PrimeRun(act));
//设置线程的名字
t1.setName("t1");
t2.setName("t2");
t1.start();
t2.start();
}
}
//创建取款线程
class PrimeRun implements Runnable{
Account act ;
PrimeRun(Account act){
this.act = act;
}
public void run() {
try {
act.withDraw(1000.0);
System.out.println(Thread.currentThread().getName()+ "取款1000.0成功，所剩余额：" + act.getBalance());
} catch (Exception e) {
e.printStackTrace();
}
}
}
//账户
class Account{
private String actno;
private double balance;
Account(){};
//给账户赋初始值
Account(String actno,double balance){
this.actno = actno;
this.balance = balance;
}
//取款余额
public void withDraw(double money){
synchronized (this) {
double after = balance - money;
try {
Thread.sleep(2000); //为达到预期效果，此处线程休眠2秒
} catch (Exception e) {
e.printStackTrace();
}
this.balance = after;
}
}
public String getActno() {
return actno;
}
public void setActno(String actno) {
this.actno = actno;
}
public double getBalance() {
return balance;
}
public void setBalance(double balance) {
this.balance = balance;
}
}
再看输出结果：
t1取款1000.0成功，所剩余额：4000.0
t2取款1000.0成功，所剩余额：3000.0
通过上述例子：
t1和t2两线程，如果当t1遇到synchronized关键字，就会找this的对象锁，如果找到this对象锁，则进入同步语句块，当该同步语句中代码执行结束后，t1线程归还this对象锁。
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