Java中的同步静态方法是否合法?
Yes. It gets the lock on the object representing the class the method is defined in (eg MyClass.class)
Yes, and it simplifies static factory methods like this:
class Foo {
private Foo() {}
public static synchronized Foo getInstance() {
if (instance == null) {
instance = new Foo();
}
return instance;
}
private static Foo instance = null;
}
Here's what it might look like if static
methods could not be synchronized
:
class Foo {
private Foo() {}
public static Foo getInstance() {
synchronized (LOCK) {
if (instance == null) {
instance = new Foo();
}
}
return instance;
}
private static Foo instance = null;
private static final Object LOCK = Foo.class;
// alternative: private static final Object LOCK = new Object();
}
Not that big a deal, it just saves 2 lines of code.
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