为什么我的synchronized依然不能保持线程安全？
package com.imooc.concurrent.test;
public class Test {
public static void main(String[] args) {
final aquryI a = new aquryI();
while(true){
new Thread("Thread A") {
public void run() {
a.read();
a.write();
a.read();
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
};
}.start();
new Thread("Thread B") {
public void run() {
a.read();
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
};
}.start();
System.out.println("\n");
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
class aquryI {
private volatile static int i;
public synchronized void write(){
i +=10;
System.out.println(Thread.currentThread().getName());
}
public synchronized void read(){
System.out.println(Thread.currentThread().getName());
System.out.println(i);
}
}
运行结果如下：
Thread A
0
Thread A
Thread A
10
Thread B
10
Thread A
10
Thread A
Thread A
20
Thread B
20
Thread A
20
Thread A
Thread A
30
Thread B
30
Thread A
30
Thread A
Thread A
40
Thread B
40
Thread A
40
Thread A
Thread A
50
Thread B
50
Thread A
50
Thread A
Thread A
60
Thread B
60
Thread A
60
Thread B
60
Thread A
Thread A
70
Thread A
70
Thread A
Thread A
80
Thread B
80
Thread A
80
Thread A
Thread A
90
Thread B
90
Thread A
90
Thread B
90
Thread A
Thread A
100
.....
Thread A
120
Thread B
120
Thread A
Thread A
130
Thread A
130
Thread B
130
Thread A
Thread A
140
Thread A
140
Thread A
Thread A
150
Thread B
150
Thread A
150
Thread A
Thread A
160
Thread B
160
Thread B
160
Thread A
160
Thread A
Thread A
170
虽然大部分时候可以保证 但是有时候还是会出现A B交替运行的现象 这是为什么？ |
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