多個線程訪問同多個對象，同步方法加static，表示此方法屬于類，所有此對象的此方法執行需要同步
package test;
public class Test5 {
public static synchronized void get(String s){
if("a".equals(s)){
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println(s);
}
public static void main(String[] args) {
final Test5 t =new Test5();
final Test5 t1 =new Test5();
new Thread(new Runnable() {
@Override
public void run() {
t.get("a");
}
}).start();
new Thread(new Runnable() {
@Override
public void run() {
t1.get("b");
}
}).start();
}
}