For static fields NO...
Let's Proove it ...
public class TestObject {
private static int dangerInt =0 ;
public TestObject () {
dangerInt++;
System.out.println (" Current Value of i :" + dangerInt + " # -- " + Thread.currentThread ().getName ());
}
}
public class ConstructorTest {
public static void main (String[] args) {
final ConstructorTest test = new ConstructorTest();
final Runnable r = new Runnable () {
public void run () {
while (true) {
try {
test.printSomething ();
Thread.sleep (500);
} catch (Exception ex) {
System.out.println (" -- Interrupted...");
ex.printStackTrace ();
}
}
}
};
for (int i = 0; i < 10; i++) {
new Thread (r).start ();
}
}
public void printSomething (){
new TestObject ();
}
}
Output : Current Value of i :2 # -- Thread-1Current Value of i :2 # -- Thread-0
Current Value of i :3 # -- Thread-2
Current Value of i :4 # -- Thread-3
Current Value of i :5 # -- Thread-4
Current Value of i :6 # -- Thread-5
Current Value of i :7 # -- Thread-6
Current Value of i :8 # -- Thread-7
Current Value of i :9 # -- Thread-8
Current Value of i :10 # -- Thread-9
Current Value of i :11 # -- Thread-1
Current Value of i :12 # -- Thread-0
Current Value of i :13 # -- Thread-2
Current Value of i :14 # -- Thread-3
Current Value of i :15 # -- Thread-4
Current Value of i :16 # -- Thread-5
Current Value of i :17 # -- Thread-6
Current Value of i :18 # -- Thread-7
Current Value of i :19 # -- Thread-8
Current Value of i :20 # -- Thread-9
Current Value of i :21 # -- Thread-1
Current Value of i :22 # -- Thread-0
Current Value of i :23 # -- Thread-2
Current Value of i :24 # -- Thread-3
Current Value of i :25 # -- Thread-4
Current Value of i :26 # -- Thread-5
Current Value of i :27 # -- Thread-6
Current Value of i :28 # -- Thread-7
Current Value of i :29 # -- Thread-8
Current Value of i :30 # -- Thread-9
Current Value of i :31 # -- Thread-1
Current Value of i :32 # -- Thread-0
Current Value of i :33 # -- Thread-2
Current Value of i :34 # -- Thread-3
Current Value of i :35 # -- Thread-4
Current Value of i :36 # -- Thread-5
Current Value of i :37 # -- Thread-6
Current Value of i :38 # -- Thread-7
Current Value of i :39 # -- Thread-8
Current Value of i :40 # -- Thread-9
Current Value of i :41 # -- Thread-1
Current Value of i :42 # -- Thread-0
Current Value of i :43 # -- Thread-2
Current Value of i :44 # -- Thread-3
Current Value of i :45 # -- Thread-4
Current Value of i :46 # -- Thread-5
Current Value of i :47 # -- Thread-6
Current Value of i :48 # -- Thread-7
Current Value of i :49 # -- Thread-8
Current Value of i :50 # -- Thread-9
Current Value of i :51 # -- Thread-1
Current Value of i :53 # -- Thread-3
Current Value of i :55 # -- Thread-5
Current Value of i :57 # -- Thread-7
Current Value of i :54 # -- Thread-6
Current Value of i :58 # -- Thread-8
Current Value of i :56 # -- Thread-4
Current Value of i :52 # -- Thread-2
Current Value of i :51 # -- Thread-0
Actually this is not an issue about constructors, this is a general synchronization issue that is unrelated with constructors. Constructors are like any other method when it comes to synchronization.
ReplyDeletepublic Class MyClass{
ReplyDeleteprivate SomeType someInstanceField;
private SomeOtherType someOtherInstanceField;
public void MyClass (SomeType someValue, SomeOtherType someOtherValue){//synchronization here is unnecessary
this.someInstanceField = someValue;
this.someOtherInstanceField = someOtherValue;
}
public void synchronized setSomeInstanceVariables (SomeType someValue, SomeOtherType someOtherValue){//synchronization here is necessary
this.someInstanceField = someValue;
this.someInstanceField = someOtherValue;
}
}
So there is small difference between constructors and any other methods bro.Think twice :)
Initialization of fields is guarenteed under JSR-133, but not mutation of static fields. IMHO You shouldn't set static fields in a constructor. ;)
ReplyDelete