Arul Jose

I could not get japanese characters displayed in my jsp. I have set content type as UTF 8.

<%@page contentType="text/html;charset=UTF-8"%>

I am not manipulating anything.

I am getting the japanese string in a request parameter and I am just printing it.

Any help would be great.

Thanks.

ARUL JOSE.

How bigger will this pool get? Any parameters which decide this? Any way to control this thru code?

Arul Jose.

While the following code is run in a loop, is there a possibility of memory leak? Has any of you come accross this before?

Runtime rt = Runtime.getRuntime(); proc = rt.exec(command); proc.waitFor();

I am doing a system call using Runtime.execute() method. I am getting the following error. Has anyone of you come accross this error. What did you do to rectify?

java.io.IOException: java.io.IOException: Cannot allocate memory|
at java.lang.UNIXProcess.<init>(UNIXProcess.java:148)|
at java.lang.ProcessImpl.start(ProcessImpl.java:65)|
at java.lang.ProcessBuilder.start(ProcessBuilder.java:451)|
at java.lang.Runtime.exec(Runtime.java:591)|
at java.lang.Runtime.exec(Runtime.java:429)|
at java.lang.Runtime.exec(Runtime.java:326)|
at export.StudioRobot.runRobot(Unknown Source)|
at export.ImageExportScheduler.executeTask(Unknown Source)|
at taskengine.internal.SchedulerBean.executeTask(SchedulerBean.java:417)|
at sun.reflect.GeneratedMethodAccessor56.invoke(Unknown Source)|
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)|
at java.lang.reflect.Method.invoke(Method.java:585)|
at mfw.bean.BeanProxy.invoke(BeanProxy.java:119)|
at $Proxy3.executeTask(Unknown Source)|
at taskengine.internal.ScheduleExecutor.executeNextTask(ScheduleExecutor.java:115)|
at taskengine.internal.ScheduleExecutor.run(ScheduleExecutor.java:41)|
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)|
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)|
at java.lang.Thread.run(Thread.java:595)|
[ July 31, 2007: Message edited by: Arul Jose ]

I am creating two thread objects and making them print from 0 to 9. I am setting different priorities. But the priorities doesn't show up in the output at all. I would like to know why.

class ThreadClass extends Thread { public int callOrder; public void run() { for(int i=0;i<10;i++) { System.out.println("Call Order : "+callOrder+" iteration : "+i); try { Thread.sleep(20); } catch(Exception e) { } } } } public class TryThreads { public static void main(String args[]) { NormalClass normalObject0 = new NormalClass(); NormalClass normalObject1 = new NormalClass(); //normalObject0.executeThis(1); //normalObject1.executeThis(2); ThreadClass threadObject0 = new ThreadClass(); threadObject0.callOrder = 1; threadObject0.setPriority(Thread.MIN_PRIORITY); threadObject0.start(); ThreadClass threadObject1 = new ThreadClass(); threadObject1.callOrder = 2; threadObject1.setPriority(Thread.MAX_PRIORITY); threadObject1.start(); } }

the output is always :


Call Order : 1 iteration : 0
Call Order : 2 iteration : 0
Call Order : 1 iteration : 1
Call Order : 2 iteration : 1
Call Order : 1 iteration : 2
Call Order : 2 iteration : 2
Call Order : 1 iteration : 3
Call Order : 2 iteration : 3
Call Order : 1 iteration : 4
Call Order : 2 iteration : 4
Call Order : 1 iteration : 5
Call Order : 2 iteration : 5
Call Order : 1 iteration : 6
Call Order : 2 iteration : 6
Call Order : 1 iteration : 7
Call Order : 2 iteration : 7
Call Order : 1 iteration : 8
Call Order : 2 iteration : 8
Call Order : 1 iteration : 9
Call Order : 2 iteration : 9



I expected something like the following

Call Order : 1 iteration : 0
Call Order : 2 iteration : 0
Call Order : 2 iteration : 1
Call Order : 1 iteration : 1
Call Order : 2 iteration : 2
Call Order : 2 iteration : 3
Call Order : 1 iteration : 2


that is i expected more priority for the second thread.

i think he says 'start with a lang like c or lisp then come to java'.

i have talked about it here.

[ March 01, 2007: Message edited by: Arul Jose ]
[ March 01, 2007: Message edited by: Arul Jose ]

Hi Ranchies,

Is there a way to keep the code for one class in multiple files?

say like having the code for Utils.java in Utils0.java, Utils1.java, Utils2.java etc.

arul jose

Dear Seema,

There are already very popular books for SCJP preparation. What have you done special to make your book stand out. Please tell.

Regards,
ARUL JOSE

First of all thanks for your answers.

wait() releases the lock so that some other thread can grab the lock, do whatever the original thread is waiting for

1. so, only when the current thread is waiting for some other thread's execution, the wait() method is called?

2. so the method wait() waits till the current thread gets a notification?

3. if it doesn't get notified, it will keep waiting?

4. when a thread says notify() there is no guarantee that the thread which we are expecting will get notified right? so if the original thread gets a notify from some other unexpected thread, the original thread may run before the 'other thread'(which it is waiting for to finish some operation) finishes operation right? so what is the point in saying wait()?

to explain thread A is saying wait() expecting B to say notify(). what if some other thread C says notify() before B says notify() and A gets notified?

ARUL JOSE

why should b release its lock before finishing operations?

6. synchronized(b) { 7. try { 8. System.out.println("Waiting for b to complete..."); 9. b.wait(); 10. } catch (InterruptedException e) {} 11. System.out.println("Total is: " + b.total); 12. }
in the given code, when the thread comes to line 9, it has already got the lock of b, why should it then wait for the lock of b?

It must be done correctly. And it must be used as it was intended.

Henry, do you mean, it is the responsibility of the 'coder' to be careful ?

public class CheckSync { private int i=0; public synchronized void method1() { i++; } public void method2() { i--; } }

We have two methods here one is synchronized and the other is not. When an object of this class is locked, only one thread can access method1() but any number of threads can access method2(). while method1() runs, method2() also can simultaneously change the value of i which is used by method1() (method1 will see a different value for i, since it was altered by method2), since it is accessible by any number of threads. Is this not making the purpose of 'synchronized' void?
[ July 19, 2006: Message edited by: Arul Jose ]

Kindly see the following code.
synchronized(b) { try { System.out.println("Waiting for b to complete..."); b.wait(); } catch (InterruptedException e) {} System.out.println("Total is: " + b.total); }

when the line "Waiting for b to complete ..." is printed, already the lock for b is gotten. Am I right? why should the current thread wait to get b? Only after getting the lock on b the synchronized(b) block can be entered isn't? Why after getting b's lock, the thread should wait?

I could not come to a conclusion why the class TestInterfaceMember is not compiling. Please see if you can help.

[aruljose@aruljose javatry]$ javac -classpath ./classes:. TestInterfaceMember.java
TestInterfaceMember.java:2: cannot find symbol
symbol : class pkg
location: class test
class TestInterfaceMember implements test.pkg.I
^
TestInterfaceMember.java:2: interface expected here
class TestInterfaceMember implements test.pkg.I
^
TestInterfaceMember.java:6: cannot find symbol
symbol : variable i
location: class TestInterfaceMember
System.out.println(i);
^
3 errors
[aruljose@aruljose javatry]$ ls classes
test/
[aruljose@aruljose javatry]$ ls classes/test/
pkg/
[aruljose@aruljose javatry]$ ls classes/test/pkg/
I.class

TestInterfaceMember.java
class TestInterfaceMember implements test.pkg.I { public static void main(String args[]) { System.out.println(i); } }

classes/test/pkg/I.java
package test.pkg; public interface I { int i = 5; }