Dog dog = Dog.INSTANCE;
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("1.txt"));
out.writeObject(dog);
out.close();
ObjectInputStream in = new ObjectInputStream(new FileInputStream("1.txt"));
Dog dog2 = (Dog)in.readObject();
in.close();
System.out.println(dog==dog2);
}
}
8.Thread.interrupted()和Thread.isInterrupted()的 区别
Thread.interrupted()方法后会清除当前线程的中断状态。
Thread.isInterrupted()则只是测试是否已经被中断。
view plaincopy to clipboardprint public class PuzzleDemo84{
public static void main(String args[]){
Thread.currentThread().interrupt();
if(Thread.currentThread().isInterrupted
()){
System.out.println
("Interrupt:"+Thread.currentThread().isInterrupted());
}
else{
System.out.println(" Not
Interrupt:"+Thread.currentThread().isInterrupted());
}
}
}
public class PuzzleDemo84{
public static void main(String args[]){
Thread.currentThread().interrupt();
if(Thread.currentThread().isInterrupted
()){
System.out.println
("Interrupt:"+Thread.currentThread().isInterrupted());
}
else{
System.out.println(" Not
Interrupt:"+Thread.currentThread().isInterrupted());
}
}
}
9.多线程下的初始化
当一个线程访问一个类的某个成员之前，都会去检查这个类是否已经被初始化。
多线程下类初始化有4种情况：
(1)这个类没被初始化。
(2)这个类被当前线程初始化。
(3)这个类被其他线程初始化。
(4)这个类已经被初始化。
当第三种情况下，如果B线程要访问A类的某个成员，则发现正在被C线程初始化，则会等待C线程初始化完毕，才会继续运行。
结论：要明确初始化顺序。
view plaincopy to clipboardprint public class PuzzleDemo85{
private static boolean initialize = true; //1
private static Thread t = new Thread(new Runnable(){ //2
public void run(){
initialize = true;
}
});
static{
System.out.println(initialize);
t.start(); //3
}
public static void main(String args[]){
try{
System.out.println("main:"+initialize);
t.join(); //4
}
catch(Exception e){}
System.out.println(initialize); //5
}
}
public class PuzzleDemo85{
private static boolean initialize = true; //1
private static Thread t = new Thread(new Runnable(){ //2
public void run(){
initialize = true;
}
});
static{
System.out.println(initialize);
t.start(); //3
}
public static void main(String args[]){
try{
System.out.println("main:"+initialize);
t.join(); //4
}
catch(Exception e){}
System.out.println(initialize); //5
}
}
作者“xiazdong的专栏”